From 719b779b6bb035e70b8603fc51c8f6fe1a196ef0 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 4 Oct 2019 15:27:32 -0700
Subject: [PATCH 1/8] Reflect CFA effects of optional chains in equality checks

---
 src/compiler/checker.ts | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 6ece23f022ab3..5f0f8241a5eca 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -18124,6 +18124,16 @@ namespace ts {
             return false;
         }
 
+        function optionalChainContainsReference(source: Node, target: Node) {
+            while (isOptionalChain(source)) {
+                source = source.expression;
+                if (isMatchingReference(source, target)) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
         // Return true if target is a property access xxx.yyy, source is a property access xxx.zzz, the declared
         // type of xxx is a union type, and yyy is a property that is possibly a discriminant. We consider a property
         // a possible discriminant if its type differs in the constituents of containing union type, and if every
@@ -19350,6 +19360,14 @@ namespace ts {
                         if (isMatchingReference(reference, right)) {
                             return narrowTypeByEquality(type, operator, left, assumeTrue);
                         }
+                        if (assumeTrue && (operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken)) {
+                            if (optionalChainContainsReference(left, reference)) {
+                                type = narrowTypeByOptionalChainContainment(type, operator, right);
+                            }
+                            else if (optionalChainContainsReference(right, reference)) {
+                                type = narrowTypeByOptionalChainContainment(type, operator, left);
+                            }
+                        }
                         if (isMatchingReferenceDiscriminant(left, declaredType)) {
                             return narrowTypeByDiscriminant(type, <AccessExpression>left, t => narrowTypeByEquality(t, operator, right, assumeTrue));
                         }
@@ -19374,6 +19392,16 @@ namespace ts {
                 return type;
             }
 
+            function narrowTypeByOptionalChainContainment(type: Type, operator: SyntaxKind, value: Expression): Type {
+                // We are in the true branch of obj?.foo === value or obj?.foo !== value. We remove undefined and null from
+                // the type of obj if (a) the operator is === and the type of value doesn't include undefined or (b) the
+                // operator is !== and the type of value is undefined.
+                const valueType = getTypeOfExpression(value);
+                return operator === SyntaxKind.EqualsEqualsEqualsToken && !(getTypeFacts(valueType) & TypeFacts.EQUndefined) ||
+                    operator === SyntaxKind.ExclamationEqualsEqualsToken && valueType.flags & TypeFlags.Undefined ?
+                    getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type;
+            }
+
             function narrowTypeByEquality(type: Type, operator: SyntaxKind, value: Expression, assumeTrue: boolean): Type {
                 if (type.flags & TypeFlags.Any) {
                     return type;

From 2447bd775f4c33667e7f8ce7edd4b7da00d0870f Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 4 Oct 2019 16:01:09 -0700
Subject: [PATCH 2/8] Update tests

---
 .../cases/conformance/controlFlow/controlFlowOptionalChain.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts b/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
index dadb1b36076db..dabeea617f4d0 100644
--- a/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
+++ b/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
@@ -61,8 +61,8 @@ o2.f;
 
 declare const o3: { x: 1, y: string } | { x: 2, y: number } | undefined;
 if (o3?.x === 1) {
-    o3; // TODO: should be `{ x: y, y: string }`
-    o3.x; // TODO: should not be an error.
+    o3;
+    o3.x;
     o3?.x;
 }
 else {

From 7d32355f957dd5547aa0a7a50d1a1c2a56d90bf8 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 4 Oct 2019 16:01:27 -0700
Subject: [PATCH 3/8] Accept new baselines

---
 .../reference/controlFlowOptionalChain.errors.txt  |  9 +++------
 .../reference/controlFlowOptionalChain.js          |  8 ++++----
 .../reference/controlFlowOptionalChain.symbols     | 12 ++++++------
 .../reference/controlFlowOptionalChain.types       | 14 +++++++-------
 4 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/tests/baselines/reference/controlFlowOptionalChain.errors.txt b/tests/baselines/reference/controlFlowOptionalChain.errors.txt
index ce46b232b3d81..0d2d268d59165 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.errors.txt
+++ b/tests/baselines/reference/controlFlowOptionalChain.errors.txt
@@ -6,7 +6,6 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(35,5): error TS2
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(39,1): error TS2722: Cannot invoke an object which is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(52,5): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(57,1): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(62,5): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(68,5): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(72,1): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(83,5): error TS2532: Object is possibly 'undefined'.
@@ -22,7 +21,7 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(134,1): error TS
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(153,9): error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
 
 
-==== tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts (22 errors) ====
+==== tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts (21 errors) ====
     // assignments in shortcutting chain
     declare const o: undefined | {
         [key: string]: any;
@@ -99,10 +98,8 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(153,9): error TS
     
     declare const o3: { x: 1, y: string } | { x: 2, y: number } | undefined;
     if (o3?.x === 1) {
-        o3; // TODO: should be `{ x: y, y: string }`
-        o3.x; // TODO: should not be an error.
-        ~~
-!!! error TS2532: Object is possibly 'undefined'.
+        o3;
+        o3.x;
         o3?.x;
     }
     else {
diff --git a/tests/baselines/reference/controlFlowOptionalChain.js b/tests/baselines/reference/controlFlowOptionalChain.js
index 58a2873f93aa1..fed8131681f08 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.js
+++ b/tests/baselines/reference/controlFlowOptionalChain.js
@@ -59,8 +59,8 @@ o2.f;
 
 declare const o3: { x: 1, y: string } | { x: 2, y: number } | undefined;
 if (o3?.x === 1) {
-    o3; // TODO: should be `{ x: y, y: string }`
-    o3.x; // TODO: should not be an error.
+    o3;
+    o3.x;
     o3?.x;
 }
 else {
@@ -206,8 +206,8 @@ o2;
 (_k = o2) === null || _k === void 0 ? void 0 : _k.f;
 o2.f;
 if (((_l = o3) === null || _l === void 0 ? void 0 : _l.x) === 1) {
-    o3; // TODO: should be `{ x: y, y: string }`
-    o3.x; // TODO: should not be an error.
+    o3;
+    o3.x;
     (_m = o3) === null || _m === void 0 ? void 0 : _m.x;
 }
 else {
diff --git a/tests/baselines/reference/controlFlowOptionalChain.symbols b/tests/baselines/reference/controlFlowOptionalChain.symbols
index 21f1de2a41026..d3390729ac424 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.symbols
+++ b/tests/baselines/reference/controlFlowOptionalChain.symbols
@@ -182,18 +182,18 @@ if (o3?.x === 1) {
 >o3 : Symbol(o3, Decl(controlFlowOptionalChain.ts, 58, 13))
 >x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19), Decl(controlFlowOptionalChain.ts, 58, 41))
 
-    o3; // TODO: should be `{ x: y, y: string }`
+    o3;
 >o3 : Symbol(o3, Decl(controlFlowOptionalChain.ts, 58, 13))
 
-    o3.x; // TODO: should not be an error.
->o3.x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19), Decl(controlFlowOptionalChain.ts, 58, 41))
+    o3.x;
+>o3.x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19))
 >o3 : Symbol(o3, Decl(controlFlowOptionalChain.ts, 58, 13))
->x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19), Decl(controlFlowOptionalChain.ts, 58, 41))
+>x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19))
 
     o3?.x;
->o3?.x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19), Decl(controlFlowOptionalChain.ts, 58, 41))
+>o3?.x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19))
 >o3 : Symbol(o3, Decl(controlFlowOptionalChain.ts, 58, 13))
->x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19), Decl(controlFlowOptionalChain.ts, 58, 41))
+>x : Symbol(x, Decl(controlFlowOptionalChain.ts, 58, 19))
 }
 else {
     o3;
diff --git a/tests/baselines/reference/controlFlowOptionalChain.types b/tests/baselines/reference/controlFlowOptionalChain.types
index a93c5b0b43f04..5b9d10b219810 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.types
+++ b/tests/baselines/reference/controlFlowOptionalChain.types
@@ -208,18 +208,18 @@ if (o3?.x === 1) {
 >x : 1 | 2 | undefined
 >1 : 1
 
-    o3; // TODO: should be `{ x: y, y: string }`
->o3 : { x: 1; y: string; } | { x: 2; y: number; } | undefined
+    o3;
+>o3 : { x: 1; y: string; }
 
-    o3.x; // TODO: should not be an error.
+    o3.x;
 >o3.x : 1
->o3 : { x: 1; y: string; } | { x: 2; y: number; } | undefined
+>o3 : { x: 1; y: string; }
 >x : 1
 
     o3?.x;
->o3?.x : 1 | undefined
->o3 : { x: 1; y: string; } | { x: 2; y: number; } | undefined
->x : 1 | undefined
+>o3?.x : 1
+>o3 : { x: 1; y: string; }
+>x : 1
 }
 else {
     o3;

From 42500d060644d07f5884c086ba1db46bc06a8419 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 4 Oct 2019 16:12:44 -0700
Subject: [PATCH 4/8] Add tests

---
 .../controlFlow/controlFlowOptionalChain.ts   | 77 +++++++++++++++++++
 1 file changed, 77 insertions(+)

diff --git a/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts b/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
index dabeea617f4d0..d04fdb9e1b0bc 100644
--- a/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
+++ b/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
@@ -161,3 +161,80 @@ function f01(x: unknown) {
         x;
     }
 }
+
+type Thing = { foo: number, bar(): number };
+
+function f10(o: Thing | undefined, value: number) {
+    if (o?.foo === value) {
+        o;
+        o.foo;
+    }
+    if (o?.["foo"] === value) {
+        o;
+        o["foo"];
+    }
+    if (o?.bar() === value) {
+        o;
+        o.bar;
+    }
+}
+
+function f11(o: Thing | null, value: number) {
+    if (o?.foo === value) {
+        o;
+        o.foo;
+    }
+    if (o?.["foo"] === value) {
+        o;
+        o["foo"];
+    }
+    if (o?.bar() === value) {
+        o;
+        o.bar;
+    }
+}
+
+function f12(o: Thing | undefined, value: number | undefined) {
+    if (o?.foo === value) {
+        o;
+        o.foo;  // Error
+    }
+    if (o?.["foo"] === value) {
+        o;
+        o["foo"];  // Error
+    }
+    if (o?.bar() === value) {
+        o;
+        o.bar;  // Error
+    }
+}
+
+function f13(o: Thing | undefined) {
+    if (o?.foo !== undefined) {
+        o;
+        o.foo;
+    }
+    if (o?.["foo"] !== undefined) {
+        o;
+        o["foo"];
+    }
+    if (o?.bar() !== undefined) {
+        o;
+        o.bar;
+    }
+}
+
+function f14(o: Thing | null) {
+    if (o?.foo !== undefined) {
+        o;
+        o.foo;
+    }
+    if (o?.["foo"] !== undefined) {
+        o;
+        o["foo"];
+    }
+    if (o?.bar() !== undefined) {
+        o;
+        o.bar;
+    }
+}

From 464d1a74c734cab6fed95e3f2245befa8d634f4b Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 4 Oct 2019 16:12:53 -0700
Subject: [PATCH 5/8] Accept new baselines

---
 .../controlFlowOptionalChain.errors.txt       |  88 +++++-
 .../reference/controlFlowOptionalChain.js     | 152 ++++++++++
 .../controlFlowOptionalChain.symbols          | 237 +++++++++++++++
 .../reference/controlFlowOptionalChain.types  | 270 ++++++++++++++++++
 4 files changed, 746 insertions(+), 1 deletion(-)

diff --git a/tests/baselines/reference/controlFlowOptionalChain.errors.txt b/tests/baselines/reference/controlFlowOptionalChain.errors.txt
index 0d2d268d59165..1c5c4b18399b5 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.errors.txt
+++ b/tests/baselines/reference/controlFlowOptionalChain.errors.txt
@@ -19,9 +19,12 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(112,1): error TS
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(130,5): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(134,1): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(153,9): error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(197,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(201,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(205,9): error TS2532: Object is possibly 'undefined'.
 
 
-==== tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts (21 errors) ====
+==== tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts (24 errors) ====
     // assignments in shortcutting chain
     declare const o: undefined | {
         [key: string]: any;
@@ -224,4 +227,87 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(153,9): error TS
             x;
         }
     }
+    
+    type Thing = { foo: number, bar(): number };
+    
+    function f10(o: Thing | undefined, value: number) {
+        if (o?.foo === value) {
+            o;
+            o.foo;
+        }
+        if (o?.["foo"] === value) {
+            o;
+            o["foo"];
+        }
+        if (o?.bar() === value) {
+            o;
+            o.bar;
+        }
+    }
+    
+    function f11(o: Thing | null, value: number) {
+        if (o?.foo === value) {
+            o;
+            o.foo;
+        }
+        if (o?.["foo"] === value) {
+            o;
+            o["foo"];
+        }
+        if (o?.bar() === value) {
+            o;
+            o.bar;
+        }
+    }
+    
+    function f12(o: Thing | undefined, value: number | undefined) {
+        if (o?.foo === value) {
+            o;
+            o.foo;  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.["foo"] === value) {
+            o;
+            o["foo"];  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.bar() === value) {
+            o;
+            o.bar;  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+    }
+    
+    function f13(o: Thing | undefined) {
+        if (o?.foo !== undefined) {
+            o;
+            o.foo;
+        }
+        if (o?.["foo"] !== undefined) {
+            o;
+            o["foo"];
+        }
+        if (o?.bar() !== undefined) {
+            o;
+            o.bar;
+        }
+    }
+    
+    function f14(o: Thing | null) {
+        if (o?.foo !== undefined) {
+            o;
+            o.foo;
+        }
+        if (o?.["foo"] !== undefined) {
+            o;
+            o["foo"];
+        }
+        if (o?.bar() !== undefined) {
+            o;
+            o.bar;
+        }
+    }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/controlFlowOptionalChain.js b/tests/baselines/reference/controlFlowOptionalChain.js
index fed8131681f08..9b42d764726bf 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.js
+++ b/tests/baselines/reference/controlFlowOptionalChain.js
@@ -159,6 +159,83 @@ function f01(x: unknown) {
         x;
     }
 }
+
+type Thing = { foo: number, bar(): number };
+
+function f10(o: Thing | undefined, value: number) {
+    if (o?.foo === value) {
+        o;
+        o.foo;
+    }
+    if (o?.["foo"] === value) {
+        o;
+        o["foo"];
+    }
+    if (o?.bar() === value) {
+        o;
+        o.bar;
+    }
+}
+
+function f11(o: Thing | null, value: number) {
+    if (o?.foo === value) {
+        o;
+        o.foo;
+    }
+    if (o?.["foo"] === value) {
+        o;
+        o["foo"];
+    }
+    if (o?.bar() === value) {
+        o;
+        o.bar;
+    }
+}
+
+function f12(o: Thing | undefined, value: number | undefined) {
+    if (o?.foo === value) {
+        o;
+        o.foo;  // Error
+    }
+    if (o?.["foo"] === value) {
+        o;
+        o["foo"];  // Error
+    }
+    if (o?.bar() === value) {
+        o;
+        o.bar;  // Error
+    }
+}
+
+function f13(o: Thing | undefined) {
+    if (o?.foo !== undefined) {
+        o;
+        o.foo;
+    }
+    if (o?.["foo"] !== undefined) {
+        o;
+        o["foo"];
+    }
+    if (o?.bar() !== undefined) {
+        o;
+        o.bar;
+    }
+}
+
+function f14(o: Thing | null) {
+    if (o?.foo !== undefined) {
+        o;
+        o.foo;
+    }
+    if (o?.["foo"] !== undefined) {
+        o;
+        o["foo"];
+    }
+    if (o?.bar() !== undefined) {
+        o;
+        o.bar;
+    }
+}
 
 
 //// [controlFlowOptionalChain.js]
@@ -286,3 +363,78 @@ function f01(x) {
         x;
     }
 }
+function f10(o, value) {
+    var _a, _b, _c;
+    if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === value) {
+        o;
+        o.foo;
+    }
+    if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === value) {
+        o;
+        o["foo"];
+    }
+    if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === value) {
+        o;
+        o.bar;
+    }
+}
+function f11(o, value) {
+    var _a, _b, _c;
+    if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === value) {
+        o;
+        o.foo;
+    }
+    if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === value) {
+        o;
+        o["foo"];
+    }
+    if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === value) {
+        o;
+        o.bar;
+    }
+}
+function f12(o, value) {
+    var _a, _b, _c;
+    if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === value) {
+        o;
+        o.foo; // Error
+    }
+    if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === value) {
+        o;
+        o["foo"]; // Error
+    }
+    if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === value) {
+        o;
+        o.bar; // Error
+    }
+}
+function f13(o) {
+    var _a, _b, _c;
+    if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) !== undefined) {
+        o;
+        o.foo;
+    }
+    if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) !== undefined) {
+        o;
+        o["foo"];
+    }
+    if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) !== undefined) {
+        o;
+        o.bar;
+    }
+}
+function f14(o) {
+    var _a, _b, _c;
+    if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) !== undefined) {
+        o;
+        o.foo;
+    }
+    if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) !== undefined) {
+        o;
+        o["foo"];
+    }
+    if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) !== undefined) {
+        o;
+        o.bar;
+    }
+}
diff --git a/tests/baselines/reference/controlFlowOptionalChain.symbols b/tests/baselines/reference/controlFlowOptionalChain.symbols
index d3390729ac424..495e6371a6330 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.symbols
+++ b/tests/baselines/reference/controlFlowOptionalChain.symbols
@@ -600,3 +600,240 @@ function f01(x: unknown) {
     }
 }
 
+type Thing = { foo: number, bar(): number };
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+
+function f10(o: Thing | undefined, value: number) {
+>f10 : Symbol(f10, Decl(controlFlowOptionalChain.ts, 161, 44))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
+
+    if (o?.foo === value) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] === value) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.bar() === value) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+    }
+}
+
+function f11(o: Thing | null, value: number) {
+>f11 : Symbol(f11, Decl(controlFlowOptionalChain.ts, 176, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 178, 29))
+
+    if (o?.foo === value) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 178, 29))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] === value) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 178, 29))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.bar() === value) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 178, 29))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+    }
+}
+
+function f12(o: Thing | undefined, value: number | undefined) {
+>f12 : Symbol(f12, Decl(controlFlowOptionalChain.ts, 191, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 193, 34))
+
+    if (o?.foo === value) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 193, 34))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+
+        o.foo;  // Error
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] === value) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 193, 34))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+
+        o["foo"];  // Error
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+    }
+    if (o?.bar() === value) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 193, 34))
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+
+        o.bar;  // Error
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+    }
+}
+
+function f13(o: Thing | undefined) {
+>f13 : Symbol(f13, Decl(controlFlowOptionalChain.ts, 206, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+
+    if (o?.foo !== undefined) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>undefined : Symbol(undefined)
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] !== undefined) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>undefined : Symbol(undefined)
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.bar() !== undefined) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>undefined : Symbol(undefined)
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+    }
+}
+
+function f14(o: Thing | null) {
+>f14 : Symbol(f14, Decl(controlFlowOptionalChain.ts, 221, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+
+    if (o?.foo !== undefined) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>undefined : Symbol(undefined)
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] !== undefined) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>undefined : Symbol(undefined)
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.bar() !== undefined) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>undefined : Symbol(undefined)
+
+        o;
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+    }
+}
+
diff --git a/tests/baselines/reference/controlFlowOptionalChain.types b/tests/baselines/reference/controlFlowOptionalChain.types
index 5b9d10b219810..0c243dc6be68b 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.types
+++ b/tests/baselines/reference/controlFlowOptionalChain.types
@@ -634,3 +634,273 @@ function f01(x: unknown) {
     }
 }
 
+type Thing = { foo: number, bar(): number };
+>Thing : Thing
+>foo : number
+>bar : () => number
+
+function f10(o: Thing | undefined, value: number) {
+>f10 : (o: Thing | undefined, value: number) => void
+>o : Thing | undefined
+>value : number
+
+    if (o?.foo === value) {
+>o?.foo === value : boolean
+>o?.foo : number | undefined
+>o : Thing | undefined
+>foo : number | undefined
+>value : number
+
+        o;
+>o : Thing
+
+        o.foo;
+>o.foo : number
+>o : Thing
+>foo : number
+    }
+    if (o?.["foo"] === value) {
+>o?.["foo"] === value : boolean
+>o?.["foo"] : number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>value : number
+
+        o;
+>o : Thing
+
+        o["foo"];
+>o["foo"] : number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (o?.bar() === value) {
+>o?.bar() === value : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>value : number
+
+        o;
+>o : Thing
+
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+}
+
+function f11(o: Thing | null, value: number) {
+>f11 : (o: Thing | null, value: number) => void
+>o : Thing | null
+>null : null
+>value : number
+
+    if (o?.foo === value) {
+>o?.foo === value : boolean
+>o?.foo : number | undefined
+>o : Thing | null
+>foo : number | undefined
+>value : number
+
+        o;
+>o : Thing
+
+        o.foo;
+>o.foo : number
+>o : Thing
+>foo : number
+    }
+    if (o?.["foo"] === value) {
+>o?.["foo"] === value : boolean
+>o?.["foo"] : number | undefined
+>o : Thing | null
+>"foo" : "foo"
+>value : number
+
+        o;
+>o : Thing
+
+        o["foo"];
+>o["foo"] : number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (o?.bar() === value) {
+>o?.bar() === value : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | null
+>bar : (() => number) | undefined
+>value : number
+
+        o;
+>o : Thing
+
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+}
+
+function f12(o: Thing | undefined, value: number | undefined) {
+>f12 : (o: Thing | undefined, value: number | undefined) => void
+>o : Thing | undefined
+>value : number | undefined
+
+    if (o?.foo === value) {
+>o?.foo === value : boolean
+>o?.foo : number | undefined
+>o : Thing | undefined
+>foo : number | undefined
+>value : number | undefined
+
+        o;
+>o : Thing | undefined
+
+        o.foo;  // Error
+>o.foo : number
+>o : Thing | undefined
+>foo : number
+    }
+    if (o?.["foo"] === value) {
+>o?.["foo"] === value : boolean
+>o?.["foo"] : number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>value : number | undefined
+
+        o;
+>o : Thing | undefined
+
+        o["foo"];  // Error
+>o["foo"] : number
+>o : Thing | undefined
+>"foo" : "foo"
+    }
+    if (o?.bar() === value) {
+>o?.bar() === value : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>value : number | undefined
+
+        o;
+>o : Thing | undefined
+
+        o.bar;  // Error
+>o.bar : () => number
+>o : Thing | undefined
+>bar : () => number
+    }
+}
+
+function f13(o: Thing | undefined) {
+>f13 : (o: Thing | undefined) => void
+>o : Thing | undefined
+
+    if (o?.foo !== undefined) {
+>o?.foo !== undefined : boolean
+>o?.foo : number | undefined
+>o : Thing | undefined
+>foo : number | undefined
+>undefined : undefined
+
+        o;
+>o : Thing
+
+        o.foo;
+>o.foo : number
+>o : Thing
+>foo : number
+    }
+    if (o?.["foo"] !== undefined) {
+>o?.["foo"] !== undefined : boolean
+>o?.["foo"] : number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>undefined : undefined
+
+        o;
+>o : Thing
+
+        o["foo"];
+>o["foo"] : number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (o?.bar() !== undefined) {
+>o?.bar() !== undefined : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>undefined : undefined
+
+        o;
+>o : Thing
+
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+}
+
+function f14(o: Thing | null) {
+>f14 : (o: Thing | null) => void
+>o : Thing | null
+>null : null
+
+    if (o?.foo !== undefined) {
+>o?.foo !== undefined : boolean
+>o?.foo : number | undefined
+>o : Thing | null
+>foo : number | undefined
+>undefined : undefined
+
+        o;
+>o : Thing
+
+        o.foo;
+>o.foo : number
+>o : Thing
+>foo : number
+    }
+    if (o?.["foo"] !== undefined) {
+>o?.["foo"] !== undefined : boolean
+>o?.["foo"] : number | undefined
+>o : Thing | null
+>"foo" : "foo"
+>undefined : undefined
+
+        o;
+>o : Thing
+
+        o["foo"];
+>o["foo"] : number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (o?.bar() !== undefined) {
+>o?.bar() !== undefined : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | null
+>bar : (() => number) | undefined
+>undefined : undefined
+
+        o;
+>o : Thing
+
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+}
+

From f7b22a0216550db5ce8ab0d11491e3d4f526c00f Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sat, 5 Oct 2019 13:08:24 -0700
Subject: [PATCH 6/8] Support typeof and instanceof

---
 src/compiler/binder.ts  |  5 ++---
 src/compiler/checker.ts | 13 +++++++++++--
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 6bd6045a55101..ee07acdac8299 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -856,9 +856,8 @@ namespace ts {
         function isNarrowableReference(expr: Expression): boolean {
             return expr.kind === SyntaxKind.Identifier || expr.kind === SyntaxKind.ThisKeyword || expr.kind === SyntaxKind.SuperKeyword ||
                 (isPropertyAccessExpression(expr) || isNonNullExpression(expr) || isParenthesizedExpression(expr)) && isNarrowableReference(expr.expression) ||
-                isElementAccessExpression(expr) &&
-                isStringOrNumericLiteralLike(expr.argumentExpression) &&
-                isNarrowableReference(expr.expression);
+                isElementAccessExpression(expr) && isStringOrNumericLiteralLike(expr.argumentExpression) && isNarrowableReference(expr.expression) ||
+                isOptionalChain(expr);
         }
 
         function hasNarrowableArgument(expr: CallExpression) {
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 5f0f8241a5eca..a759f7179b1a7 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -19360,7 +19360,7 @@ namespace ts {
                         if (isMatchingReference(reference, right)) {
                             return narrowTypeByEquality(type, operator, left, assumeTrue);
                         }
-                        if (assumeTrue && (operator === SyntaxKind.EqualsEqualsEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken)) {
+                        if (assumeTrue && strictNullChecks) {
                             if (optionalChainContainsReference(left, reference)) {
                                 type = narrowTypeByOptionalChainContainment(type, operator, right);
                             }
@@ -19397,7 +19397,9 @@ namespace ts {
                 // the type of obj if (a) the operator is === and the type of value doesn't include undefined or (b) the
                 // operator is !== and the type of value is undefined.
                 const valueType = getTypeOfExpression(value);
-                return operator === SyntaxKind.EqualsEqualsEqualsToken && !(getTypeFacts(valueType) & TypeFacts.EQUndefined) ||
+                return operator === SyntaxKind.EqualsEqualsToken && !(getTypeFacts(valueType) & TypeFacts.EQUndefinedOrNull) ||
+                    operator === SyntaxKind.EqualsEqualsEqualsToken && !(getTypeFacts(valueType) & TypeFacts.EQUndefined) ||
+                    operator === SyntaxKind.ExclamationEqualsToken && valueType.flags & TypeFlags.Nullable ||
                     operator === SyntaxKind.ExclamationEqualsEqualsToken && valueType.flags & TypeFlags.Undefined ?
                     getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull) : type;
             }
@@ -19452,6 +19454,10 @@ namespace ts {
                 // We have '==', '!=', '===', or !==' operator with 'typeof xxx' and string literal operands
                 const target = getReferenceCandidate(typeOfExpr.expression);
                 if (!isMatchingReference(reference, target)) {
+                    if (assumeTrue && (operator === SyntaxKind.EqualsEqualsToken || operator === SyntaxKind.EqualsEqualsEqualsToken) &&
+                        strictNullChecks && optionalChainContainsReference(target, reference)) {
+                        return getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
+                    }
                     // For a reference of the form 'x.y', a 'typeof x === ...' type guard resets the
                     // narrowed type of 'y' to its declared type.
                     if (containsMatchingReference(reference, target)) {
@@ -19633,6 +19639,9 @@ namespace ts {
             function narrowTypeByInstanceof(type: Type, expr: BinaryExpression, assumeTrue: boolean): Type {
                 const left = getReferenceCandidate(expr.left);
                 if (!isMatchingReference(reference, left)) {
+                    if (assumeTrue && strictNullChecks && optionalChainContainsReference(left, reference)) {
+                        return getTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
+                    }
                     // For a reference of the form 'x.y', an 'x instanceof T' type guard resets the
                     // narrowed type of 'y' to its declared type. We do this because preceding 'x.y'
                     // references might reference a different 'y' property. However, we make an exception

From f88518187ba5aa6ee0998b18cd78b6136834d1ab Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sat, 5 Oct 2019 13:08:31 -0700
Subject: [PATCH 7/8] Add tests

---
 .../controlFlow/controlFlowOptionalChain.ts   | 125 +++++++++++++++---
 1 file changed, 109 insertions(+), 16 deletions(-)

diff --git a/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts b/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
index d04fdb9e1b0bc..f54275f309c34 100644
--- a/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
+++ b/tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts
@@ -162,79 +162,172 @@ function f01(x: unknown) {
     }
 }
 
-type Thing = { foo: number, bar(): number };
+type Thing = { foo: string | number, bar(): number, baz: object };
 
 function f10(o: Thing | undefined, value: number) {
     if (o?.foo === value) {
-        o;
         o.foo;
     }
     if (o?.["foo"] === value) {
-        o;
         o["foo"];
     }
     if (o?.bar() === value) {
-        o;
+        o.bar;
+    }
+    if (o?.foo == value) {
+        o.foo;
+    }
+    if (o?.["foo"] == value) {
+        o["foo"];
+    }
+    if (o?.bar() == value) {
         o.bar;
     }
 }
 
 function f11(o: Thing | null, value: number) {
     if (o?.foo === value) {
-        o;
         o.foo;
     }
     if (o?.["foo"] === value) {
-        o;
         o["foo"];
     }
     if (o?.bar() === value) {
-        o;
+        o.bar;
+    }
+    if (o?.foo == value) {
+        o.foo;
+    }
+    if (o?.["foo"] == value) {
+        o["foo"];
+    }
+    if (o?.bar() == value) {
         o.bar;
     }
 }
 
 function f12(o: Thing | undefined, value: number | undefined) {
     if (o?.foo === value) {
-        o;
         o.foo;  // Error
     }
     if (o?.["foo"] === value) {
-        o;
         o["foo"];  // Error
     }
     if (o?.bar() === value) {
-        o;
+        o.bar;  // Error
+    }
+    if (o?.foo == value) {
+        o.foo;  // Error
+    }
+    if (o?.["foo"] == value) {
+        o["foo"];  // Error
+    }
+    if (o?.bar() == value) {
+        o.bar;  // Error
+    }
+}
+
+function f12a(o: Thing | undefined, value: number | null) {
+    if (o?.foo === value) {
+        o.foo;
+    }
+    if (o?.["foo"] === value) {
+        o["foo"];
+    }
+    if (o?.bar() === value) {
+        o.bar;
+    }
+    if (o?.foo == value) {
+        o.foo;  // Error
+    }
+    if (o?.["foo"] == value) {
+        o["foo"];  // Error
+    }
+    if (o?.bar() == value) {
         o.bar;  // Error
     }
 }
 
 function f13(o: Thing | undefined) {
     if (o?.foo !== undefined) {
-        o;
         o.foo;
     }
     if (o?.["foo"] !== undefined) {
-        o;
         o["foo"];
     }
     if (o?.bar() !== undefined) {
-        o;
+        o.bar;
+    }
+    if (o?.foo != undefined) {
+        o.foo;
+    }
+    if (o?.["foo"] != undefined) {
+        o["foo"];
+    }
+    if (o?.bar() != undefined) {
+        o.bar;
+    }
+}
+
+function f13a(o: Thing | undefined) {
+    if (o?.foo !== null) {
+        o.foo;  // Error
+    }
+    if (o?.["foo"] !== null) {
+        o["foo"];  // Error
+    }
+    if (o?.bar() !== null) {
+        o.bar;  // Error
+    }
+    if (o?.foo != null) {
+        o.foo;
+    }
+    if (o?.["foo"] != null) {
+        o["foo"];
+    }
+    if (o?.bar() != null) {
         o.bar;
     }
 }
 
 function f14(o: Thing | null) {
     if (o?.foo !== undefined) {
-        o;
         o.foo;
     }
     if (o?.["foo"] !== undefined) {
-        o;
         o["foo"];
     }
     if (o?.bar() !== undefined) {
-        o;
         o.bar;
     }
 }
+
+function f20(o: Thing | undefined) {
+    if (typeof o?.foo === "number") {
+        o.foo;
+    }
+    if (typeof o?.["foo"] === "number") {
+        o["foo"];
+    }
+    if (typeof o?.bar() === "number") {
+        o.bar;
+    }
+    if (o?.baz instanceof Error) {
+        o.baz;
+    }
+}
+
+function f21(o: Thing | null) {
+    if (typeof o?.foo === "number") {
+        o.foo;
+    }
+    if (typeof o?.["foo"] === "number") {
+        o["foo"];
+    }
+    if (typeof o?.bar() === "number") {
+        o.bar;
+    }
+    if (o?.baz instanceof Error) {
+        o.baz;
+    }
+}

From 99cec3a0d6875f842c666f8021228e069beab2d6 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sat, 5 Oct 2019 13:08:39 -0700
Subject: [PATCH 8/8] Accept new baselines

---
 .../controlFlowOptionalChain.errors.txt       | 160 +++++-
 .../reference/controlFlowOptionalChain.js     | 256 +++++++--
 .../controlFlowOptionalChain.symbols          | 494 +++++++++++++----
 .../reference/controlFlowOptionalChain.types  | 497 ++++++++++++++++--
 4 files changed, 1194 insertions(+), 213 deletions(-)

diff --git a/tests/baselines/reference/controlFlowOptionalChain.errors.txt b/tests/baselines/reference/controlFlowOptionalChain.errors.txt
index 1c5c4b18399b5..987dca335dccc 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.errors.txt
+++ b/tests/baselines/reference/controlFlowOptionalChain.errors.txt
@@ -19,12 +19,21 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(112,1): error TS
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(130,5): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(134,1): error TS2532: Object is possibly 'undefined'.
 tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(153,9): error TS2775: Assertions require every name in the call target to be declared with an explicit type annotation.
-tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(197,9): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(201,9): error TS2532: Object is possibly 'undefined'.
-tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(205,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(208,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(211,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(214,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(217,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(220,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(223,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(238,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(241,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(244,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(271,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(274,9): error TS2532: Object is possibly 'undefined'.
+tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(277,9): error TS2532: Object is possibly 'undefined'.
 
 
-==== tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts (24 errors) ====
+==== tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts (33 errors) ====
     // assignments in shortcutting chain
     declare const o: undefined | {
         [key: string]: any;
@@ -228,53 +237,104 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(205,9): error TS
         }
     }
     
-    type Thing = { foo: number, bar(): number };
+    type Thing = { foo: string | number, bar(): number, baz: object };
     
     function f10(o: Thing | undefined, value: number) {
         if (o?.foo === value) {
-            o;
             o.foo;
         }
         if (o?.["foo"] === value) {
-            o;
             o["foo"];
         }
         if (o?.bar() === value) {
-            o;
+            o.bar;
+        }
+        if (o?.foo == value) {
+            o.foo;
+        }
+        if (o?.["foo"] == value) {
+            o["foo"];
+        }
+        if (o?.bar() == value) {
             o.bar;
         }
     }
     
     function f11(o: Thing | null, value: number) {
         if (o?.foo === value) {
-            o;
             o.foo;
         }
         if (o?.["foo"] === value) {
-            o;
             o["foo"];
         }
         if (o?.bar() === value) {
-            o;
+            o.bar;
+        }
+        if (o?.foo == value) {
+            o.foo;
+        }
+        if (o?.["foo"] == value) {
+            o["foo"];
+        }
+        if (o?.bar() == value) {
             o.bar;
         }
     }
     
     function f12(o: Thing | undefined, value: number | undefined) {
         if (o?.foo === value) {
-            o;
             o.foo;  // Error
             ~
 !!! error TS2532: Object is possibly 'undefined'.
         }
         if (o?.["foo"] === value) {
-            o;
             o["foo"];  // Error
             ~
 !!! error TS2532: Object is possibly 'undefined'.
         }
         if (o?.bar() === value) {
-            o;
+            o.bar;  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.foo == value) {
+            o.foo;  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.["foo"] == value) {
+            o["foo"];  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.bar() == value) {
+            o.bar;  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+    }
+    
+    function f12a(o: Thing | undefined, value: number | null) {
+        if (o?.foo === value) {
+            o.foo;
+        }
+        if (o?.["foo"] === value) {
+            o["foo"];
+        }
+        if (o?.bar() === value) {
+            o.bar;
+        }
+        if (o?.foo == value) {
+            o.foo;  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.["foo"] == value) {
+            o["foo"];  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.bar() == value) {
             o.bar;  // Error
             ~
 !!! error TS2532: Object is possibly 'undefined'.
@@ -283,31 +343,91 @@ tests/cases/conformance/controlFlow/controlFlowOptionalChain.ts(205,9): error TS
     
     function f13(o: Thing | undefined) {
         if (o?.foo !== undefined) {
-            o;
             o.foo;
         }
         if (o?.["foo"] !== undefined) {
-            o;
             o["foo"];
         }
         if (o?.bar() !== undefined) {
-            o;
+            o.bar;
+        }
+        if (o?.foo != undefined) {
+            o.foo;
+        }
+        if (o?.["foo"] != undefined) {
+            o["foo"];
+        }
+        if (o?.bar() != undefined) {
+            o.bar;
+        }
+    }
+    
+    function f13a(o: Thing | undefined) {
+        if (o?.foo !== null) {
+            o.foo;  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.["foo"] !== null) {
+            o["foo"];  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.bar() !== null) {
+            o.bar;  // Error
+            ~
+!!! error TS2532: Object is possibly 'undefined'.
+        }
+        if (o?.foo != null) {
+            o.foo;
+        }
+        if (o?.["foo"] != null) {
+            o["foo"];
+        }
+        if (o?.bar() != null) {
             o.bar;
         }
     }
     
     function f14(o: Thing | null) {
         if (o?.foo !== undefined) {
-            o;
             o.foo;
         }
         if (o?.["foo"] !== undefined) {
-            o;
             o["foo"];
         }
         if (o?.bar() !== undefined) {
-            o;
             o.bar;
         }
     }
+    
+    function f20(o: Thing | undefined) {
+        if (typeof o?.foo === "number") {
+            o.foo;
+        }
+        if (typeof o?.["foo"] === "number") {
+            o["foo"];
+        }
+        if (typeof o?.bar() === "number") {
+            o.bar;
+        }
+        if (o?.baz instanceof Error) {
+            o.baz;
+        }
+    }
+    
+    function f21(o: Thing | null) {
+        if (typeof o?.foo === "number") {
+            o.foo;
+        }
+        if (typeof o?.["foo"] === "number") {
+            o["foo"];
+        }
+        if (typeof o?.bar() === "number") {
+            o.bar;
+        }
+        if (o?.baz instanceof Error) {
+            o.baz;
+        }
+    }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/controlFlowOptionalChain.js b/tests/baselines/reference/controlFlowOptionalChain.js
index 9b42d764726bf..214515280350b 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.js
+++ b/tests/baselines/reference/controlFlowOptionalChain.js
@@ -160,82 +160,175 @@ function f01(x: unknown) {
     }
 }
 
-type Thing = { foo: number, bar(): number };
+type Thing = { foo: string | number, bar(): number, baz: object };
 
 function f10(o: Thing | undefined, value: number) {
     if (o?.foo === value) {
-        o;
         o.foo;
     }
     if (o?.["foo"] === value) {
-        o;
         o["foo"];
     }
     if (o?.bar() === value) {
-        o;
+        o.bar;
+    }
+    if (o?.foo == value) {
+        o.foo;
+    }
+    if (o?.["foo"] == value) {
+        o["foo"];
+    }
+    if (o?.bar() == value) {
         o.bar;
     }
 }
 
 function f11(o: Thing | null, value: number) {
     if (o?.foo === value) {
-        o;
         o.foo;
     }
     if (o?.["foo"] === value) {
-        o;
         o["foo"];
     }
     if (o?.bar() === value) {
-        o;
+        o.bar;
+    }
+    if (o?.foo == value) {
+        o.foo;
+    }
+    if (o?.["foo"] == value) {
+        o["foo"];
+    }
+    if (o?.bar() == value) {
         o.bar;
     }
 }
 
 function f12(o: Thing | undefined, value: number | undefined) {
     if (o?.foo === value) {
-        o;
         o.foo;  // Error
     }
     if (o?.["foo"] === value) {
-        o;
         o["foo"];  // Error
     }
     if (o?.bar() === value) {
-        o;
+        o.bar;  // Error
+    }
+    if (o?.foo == value) {
+        o.foo;  // Error
+    }
+    if (o?.["foo"] == value) {
+        o["foo"];  // Error
+    }
+    if (o?.bar() == value) {
+        o.bar;  // Error
+    }
+}
+
+function f12a(o: Thing | undefined, value: number | null) {
+    if (o?.foo === value) {
+        o.foo;
+    }
+    if (o?.["foo"] === value) {
+        o["foo"];
+    }
+    if (o?.bar() === value) {
+        o.bar;
+    }
+    if (o?.foo == value) {
+        o.foo;  // Error
+    }
+    if (o?.["foo"] == value) {
+        o["foo"];  // Error
+    }
+    if (o?.bar() == value) {
         o.bar;  // Error
     }
 }
 
 function f13(o: Thing | undefined) {
     if (o?.foo !== undefined) {
-        o;
         o.foo;
     }
     if (o?.["foo"] !== undefined) {
-        o;
         o["foo"];
     }
     if (o?.bar() !== undefined) {
-        o;
+        o.bar;
+    }
+    if (o?.foo != undefined) {
+        o.foo;
+    }
+    if (o?.["foo"] != undefined) {
+        o["foo"];
+    }
+    if (o?.bar() != undefined) {
+        o.bar;
+    }
+}
+
+function f13a(o: Thing | undefined) {
+    if (o?.foo !== null) {
+        o.foo;  // Error
+    }
+    if (o?.["foo"] !== null) {
+        o["foo"];  // Error
+    }
+    if (o?.bar() !== null) {
+        o.bar;  // Error
+    }
+    if (o?.foo != null) {
+        o.foo;
+    }
+    if (o?.["foo"] != null) {
+        o["foo"];
+    }
+    if (o?.bar() != null) {
         o.bar;
     }
 }
 
 function f14(o: Thing | null) {
     if (o?.foo !== undefined) {
-        o;
         o.foo;
     }
     if (o?.["foo"] !== undefined) {
-        o;
         o["foo"];
     }
     if (o?.bar() !== undefined) {
-        o;
         o.bar;
     }
 }
+
+function f20(o: Thing | undefined) {
+    if (typeof o?.foo === "number") {
+        o.foo;
+    }
+    if (typeof o?.["foo"] === "number") {
+        o["foo"];
+    }
+    if (typeof o?.bar() === "number") {
+        o.bar;
+    }
+    if (o?.baz instanceof Error) {
+        o.baz;
+    }
+}
+
+function f21(o: Thing | null) {
+    if (typeof o?.foo === "number") {
+        o.foo;
+    }
+    if (typeof o?.["foo"] === "number") {
+        o["foo"];
+    }
+    if (typeof o?.bar() === "number") {
+        o.bar;
+    }
+    if (o?.baz instanceof Error) {
+        o.baz;
+    }
+}
 
 
 //// [controlFlowOptionalChain.js]
@@ -364,77 +457,170 @@ function f01(x) {
     }
 }
 function f10(o, value) {
-    var _a, _b, _c;
+    var _a, _b, _c, _d, _e, _f;
     if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === value) {
-        o;
         o.foo;
     }
     if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === value) {
-        o;
         o["foo"];
     }
     if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === value) {
-        o;
+        o.bar;
+    }
+    if (((_d = o) === null || _d === void 0 ? void 0 : _d.foo) == value) {
+        o.foo;
+    }
+    if (((_e = o) === null || _e === void 0 ? void 0 : _e["foo"]) == value) {
+        o["foo"];
+    }
+    if (((_f = o) === null || _f === void 0 ? void 0 : _f.bar()) == value) {
         o.bar;
     }
 }
 function f11(o, value) {
-    var _a, _b, _c;
+    var _a, _b, _c, _d, _e, _f;
     if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === value) {
-        o;
         o.foo;
     }
     if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === value) {
-        o;
         o["foo"];
     }
     if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === value) {
-        o;
+        o.bar;
+    }
+    if (((_d = o) === null || _d === void 0 ? void 0 : _d.foo) == value) {
+        o.foo;
+    }
+    if (((_e = o) === null || _e === void 0 ? void 0 : _e["foo"]) == value) {
+        o["foo"];
+    }
+    if (((_f = o) === null || _f === void 0 ? void 0 : _f.bar()) == value) {
         o.bar;
     }
 }
 function f12(o, value) {
-    var _a, _b, _c;
+    var _a, _b, _c, _d, _e, _f;
     if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === value) {
-        o;
         o.foo; // Error
     }
     if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === value) {
-        o;
         o["foo"]; // Error
     }
     if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === value) {
-        o;
+        o.bar; // Error
+    }
+    if (((_d = o) === null || _d === void 0 ? void 0 : _d.foo) == value) {
+        o.foo; // Error
+    }
+    if (((_e = o) === null || _e === void 0 ? void 0 : _e["foo"]) == value) {
+        o["foo"]; // Error
+    }
+    if (((_f = o) === null || _f === void 0 ? void 0 : _f.bar()) == value) {
+        o.bar; // Error
+    }
+}
+function f12a(o, value) {
+    var _a, _b, _c, _d, _e, _f;
+    if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === value) {
+        o.foo;
+    }
+    if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === value) {
+        o["foo"];
+    }
+    if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === value) {
+        o.bar;
+    }
+    if (((_d = o) === null || _d === void 0 ? void 0 : _d.foo) == value) {
+        o.foo; // Error
+    }
+    if (((_e = o) === null || _e === void 0 ? void 0 : _e["foo"]) == value) {
+        o["foo"]; // Error
+    }
+    if (((_f = o) === null || _f === void 0 ? void 0 : _f.bar()) == value) {
         o.bar; // Error
     }
 }
 function f13(o) {
-    var _a, _b, _c;
+    var _a, _b, _c, _d, _e, _f;
     if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) !== undefined) {
-        o;
         o.foo;
     }
     if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) !== undefined) {
-        o;
         o["foo"];
     }
     if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) !== undefined) {
-        o;
+        o.bar;
+    }
+    if (((_d = o) === null || _d === void 0 ? void 0 : _d.foo) != undefined) {
+        o.foo;
+    }
+    if (((_e = o) === null || _e === void 0 ? void 0 : _e["foo"]) != undefined) {
+        o["foo"];
+    }
+    if (((_f = o) === null || _f === void 0 ? void 0 : _f.bar()) != undefined) {
+        o.bar;
+    }
+}
+function f13a(o) {
+    var _a, _b, _c, _d, _e, _f;
+    if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) !== null) {
+        o.foo; // Error
+    }
+    if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) !== null) {
+        o["foo"]; // Error
+    }
+    if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) !== null) {
+        o.bar; // Error
+    }
+    if (((_d = o) === null || _d === void 0 ? void 0 : _d.foo) != null) {
+        o.foo;
+    }
+    if (((_e = o) === null || _e === void 0 ? void 0 : _e["foo"]) != null) {
+        o["foo"];
+    }
+    if (((_f = o) === null || _f === void 0 ? void 0 : _f.bar()) != null) {
         o.bar;
     }
 }
 function f14(o) {
     var _a, _b, _c;
     if (((_a = o) === null || _a === void 0 ? void 0 : _a.foo) !== undefined) {
-        o;
         o.foo;
     }
     if (((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) !== undefined) {
-        o;
         o["foo"];
     }
     if (((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) !== undefined) {
-        o;
         o.bar;
     }
 }
+function f20(o) {
+    var _a, _b, _c, _d;
+    if (typeof ((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === "number") {
+        o.foo;
+    }
+    if (typeof ((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === "number") {
+        o["foo"];
+    }
+    if (typeof ((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === "number") {
+        o.bar;
+    }
+    if (((_d = o) === null || _d === void 0 ? void 0 : _d.baz) instanceof Error) {
+        o.baz;
+    }
+}
+function f21(o) {
+    var _a, _b, _c, _d;
+    if (typeof ((_a = o) === null || _a === void 0 ? void 0 : _a.foo) === "number") {
+        o.foo;
+    }
+    if (typeof ((_b = o) === null || _b === void 0 ? void 0 : _b["foo"]) === "number") {
+        o["foo"];
+    }
+    if (typeof ((_c = o) === null || _c === void 0 ? void 0 : _c.bar()) === "number") {
+        o.bar;
+    }
+    if (((_d = o) === null || _d === void 0 ? void 0 : _d.baz) instanceof Error) {
+        o.baz;
+    }
+}
diff --git a/tests/baselines/reference/controlFlowOptionalChain.symbols b/tests/baselines/reference/controlFlowOptionalChain.symbols
index 495e6371a6330..2665a960a568a 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.symbols
+++ b/tests/baselines/reference/controlFlowOptionalChain.symbols
@@ -600,13 +600,14 @@ function f01(x: unknown) {
     }
 }
 
-type Thing = { foo: number, bar(): number };
+type Thing = { foo: string | number, bar(): number, baz: object };
 >Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
 
 function f10(o: Thing | undefined, value: number) {
->f10 : Symbol(f10, Decl(controlFlowOptionalChain.ts, 161, 44))
+>f10 : Symbol(f10, Decl(controlFlowOptionalChain.ts, 161, 66))
 >o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
 >Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
 >value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
@@ -617,9 +618,6 @@ function f10(o: Thing | undefined, value: number) {
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
 >value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
-
         o.foo;
 >o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
 >o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
@@ -629,211 +627,505 @@ function f10(o: Thing | undefined, value: number) {
 >o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
 >value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
-
         o["foo"];
 >o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
 >"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.bar() === value) {
->o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+    if (o?.foo == value) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
 >o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
 >value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
 
-        o;
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] == value) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.bar() == value) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
 >o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 163, 34))
 
         o.bar;
->o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
 >o : Symbol(o, Decl(controlFlowOptionalChain.ts, 163, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
     }
 }
 
 function f11(o: Thing | null, value: number) {
->f11 : Symbol(f11, Decl(controlFlowOptionalChain.ts, 176, 1))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>f11 : Symbol(f11, Decl(controlFlowOptionalChain.ts, 182, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
 >Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
->value : Symbol(value, Decl(controlFlowOptionalChain.ts, 178, 29))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 184, 29))
 
     if (o?.foo === value) {
 >o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->value : Symbol(value, Decl(controlFlowOptionalChain.ts, 178, 29))
-
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 184, 29))
 
         o.foo;
 >o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.["foo"] === value) {
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
->value : Symbol(value, Decl(controlFlowOptionalChain.ts, 178, 29))
-
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 184, 29))
 
         o["foo"];
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
 >"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.bar() === value) {
->o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->value : Symbol(value, Decl(controlFlowOptionalChain.ts, 178, 29))
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 184, 29))
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+    if (o?.foo == value) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 184, 29))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] == value) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 184, 29))
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.bar() == value) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 184, 29))
 
         o.bar;
->o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 178, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 184, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
     }
 }
 
 function f12(o: Thing | undefined, value: number | undefined) {
->f12 : Symbol(f12, Decl(controlFlowOptionalChain.ts, 191, 1))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>f12 : Symbol(f12, Decl(controlFlowOptionalChain.ts, 203, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
 >Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
->value : Symbol(value, Decl(controlFlowOptionalChain.ts, 193, 34))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 205, 34))
 
     if (o?.foo === value) {
 >o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->value : Symbol(value, Decl(controlFlowOptionalChain.ts, 193, 34))
-
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 205, 34))
 
         o.foo;  // Error
 >o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.["foo"] === value) {
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
->value : Symbol(value, Decl(controlFlowOptionalChain.ts, 193, 34))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 205, 34))
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+        o["foo"];  // Error
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+    }
+    if (o?.bar() === value) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 205, 34))
+
+        o.bar;  // Error
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+    if (o?.foo == value) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 205, 34))
+
+        o.foo;  // Error
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] == value) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 205, 34))
 
         o["foo"];  // Error
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+    }
+    if (o?.bar() == value) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 205, 34))
+
+        o.bar;  // Error
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 205, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+}
+
+function f12a(o: Thing | undefined, value: number | null) {
+>f12a : Symbol(f12a, Decl(controlFlowOptionalChain.ts, 224, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 226, 35))
+
+    if (o?.foo === value) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 226, 35))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] === value) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 226, 35))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.bar() === value) {
->o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->value : Symbol(value, Decl(controlFlowOptionalChain.ts, 193, 34))
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 226, 35))
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+    if (o?.foo == value) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 226, 35))
+
+        o.foo;  // Error
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] == value) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 226, 35))
+
+        o["foo"];  // Error
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+    }
+    if (o?.bar() == value) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>value : Symbol(value, Decl(controlFlowOptionalChain.ts, 226, 35))
 
         o.bar;  // Error
->o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 193, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 226, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
     }
 }
 
 function f13(o: Thing | undefined) {
->f13 : Symbol(f13, Decl(controlFlowOptionalChain.ts, 206, 1))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>f13 : Symbol(f13, Decl(controlFlowOptionalChain.ts, 245, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
 >Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
 
     if (o?.foo !== undefined) {
 >o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
 >undefined : Symbol(undefined)
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
-
         o.foo;
 >o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.["foo"] !== undefined) {
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
 >undefined : Symbol(undefined)
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
-
         o["foo"];
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
 >"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.bar() !== undefined) {
->o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>undefined : Symbol(undefined)
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+    if (o?.foo != undefined) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>undefined : Symbol(undefined)
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] != undefined) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
 >undefined : Symbol(undefined)
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.bar() != undefined) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>undefined : Symbol(undefined)
 
         o.bar;
->o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 208, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 247, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+}
+
+function f13a(o: Thing | undefined) {
+>f13a : Symbol(f13a, Decl(controlFlowOptionalChain.ts, 266, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+
+    if (o?.foo !== null) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+
+        o.foo;  // Error
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] !== null) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+
+        o["foo"];  // Error
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+    }
+    if (o?.bar() !== null) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+
+        o.bar;  // Error
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+    if (o?.foo != null) {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.["foo"] != null) {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (o?.bar() != null) {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 268, 14))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
     }
 }
 
 function f14(o: Thing | null) {
->f14 : Symbol(f14, Decl(controlFlowOptionalChain.ts, 221, 1))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>f14 : Symbol(f14, Decl(controlFlowOptionalChain.ts, 287, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 289, 13))
 >Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
 
     if (o?.foo !== undefined) {
 >o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 289, 13))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
 >undefined : Symbol(undefined)
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
-
         o.foo;
 >o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 289, 13))
 >foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.["foo"] !== undefined) {
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 289, 13))
 >undefined : Symbol(undefined)
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
-
         o["foo"];
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 289, 13))
 >"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
     }
     if (o?.bar() !== undefined) {
->o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 289, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
 >undefined : Symbol(undefined)
 
-        o;
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 289, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+}
+
+function f20(o: Thing | undefined) {
+>f20 : Symbol(f20, Decl(controlFlowOptionalChain.ts, 299, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+
+    if (typeof o?.foo === "number") {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (typeof o?.["foo"] === "number") {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (typeof o?.bar() === "number") {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
 
         o.bar;
->o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
->o : Symbol(o, Decl(controlFlowOptionalChain.ts, 223, 13))
->bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 27))
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+    if (o?.baz instanceof Error) {
+>o?.baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+>baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+        o.baz;
+>o.baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 301, 13))
+>baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
+    }
+}
+
+function f21(o: Thing | null) {
+>f21 : Symbol(f21, Decl(controlFlowOptionalChain.ts, 314, 1))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+>Thing : Symbol(Thing, Decl(controlFlowOptionalChain.ts, 159, 1))
+
+    if (typeof o?.foo === "number") {
+>o?.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+
+        o.foo;
+>o.foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+>foo : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (typeof o?.["foo"] === "number") {
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+
+        o["foo"];
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+>"foo" : Symbol(foo, Decl(controlFlowOptionalChain.ts, 161, 14))
+    }
+    if (typeof o?.bar() === "number") {
+>o?.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+
+        o.bar;
+>o.bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+>bar : Symbol(bar, Decl(controlFlowOptionalChain.ts, 161, 36))
+    }
+    if (o?.baz instanceof Error) {
+>o?.baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+>baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
+>Error : Symbol(Error, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+
+        o.baz;
+>o.baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
+>o : Symbol(o, Decl(controlFlowOptionalChain.ts, 316, 13))
+>baz : Symbol(baz, Decl(controlFlowOptionalChain.ts, 161, 51))
     }
 }
 
diff --git a/tests/baselines/reference/controlFlowOptionalChain.types b/tests/baselines/reference/controlFlowOptionalChain.types
index 0c243dc6be68b..ffec7d1525e4e 100644
--- a/tests/baselines/reference/controlFlowOptionalChain.types
+++ b/tests/baselines/reference/controlFlowOptionalChain.types
@@ -634,10 +634,11 @@ function f01(x: unknown) {
     }
 }
 
-type Thing = { foo: number, bar(): number };
+type Thing = { foo: string | number, bar(): number, baz: object };
 >Thing : Thing
->foo : number
+>foo : string | number
 >bar : () => number
+>baz : object
 
 function f10(o: Thing | undefined, value: number) {
 >f10 : (o: Thing | undefined, value: number) => void
@@ -646,14 +647,11 @@ function f10(o: Thing | undefined, value: number) {
 
     if (o?.foo === value) {
 >o?.foo === value : boolean
->o?.foo : number | undefined
+>o?.foo : string | number | undefined
 >o : Thing | undefined
->foo : number | undefined
+>foo : string | number | undefined
 >value : number
 
-        o;
->o : Thing
-
         o.foo;
 >o.foo : number
 >o : Thing
@@ -661,14 +659,11 @@ function f10(o: Thing | undefined, value: number) {
     }
     if (o?.["foo"] === value) {
 >o?.["foo"] === value : boolean
->o?.["foo"] : number | undefined
+>o?.["foo"] : string | number | undefined
 >o : Thing | undefined
 >"foo" : "foo"
 >value : number
 
-        o;
->o : Thing
-
         o["foo"];
 >o["foo"] : number
 >o : Thing
@@ -682,8 +677,42 @@ function f10(o: Thing | undefined, value: number) {
 >bar : (() => number) | undefined
 >value : number
 
-        o;
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+    if (o?.foo == value) {
+>o?.foo == value : boolean
+>o?.foo : string | number | undefined
+>o : Thing | undefined
+>foo : string | number | undefined
+>value : number
+
+        o.foo;
+>o.foo : string | number
+>o : Thing
+>foo : string | number
+    }
+    if (o?.["foo"] == value) {
+>o?.["foo"] == value : boolean
+>o?.["foo"] : string | number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>value : number
+
+        o["foo"];
+>o["foo"] : string | number
 >o : Thing
+>"foo" : "foo"
+    }
+    if (o?.bar() == value) {
+>o?.bar() == value : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>value : number
 
         o.bar;
 >o.bar : () => number
@@ -700,14 +729,11 @@ function f11(o: Thing | null, value: number) {
 
     if (o?.foo === value) {
 >o?.foo === value : boolean
->o?.foo : number | undefined
+>o?.foo : string | number | undefined
 >o : Thing | null
->foo : number | undefined
+>foo : string | number | undefined
 >value : number
 
-        o;
->o : Thing
-
         o.foo;
 >o.foo : number
 >o : Thing
@@ -715,14 +741,11 @@ function f11(o: Thing | null, value: number) {
     }
     if (o?.["foo"] === value) {
 >o?.["foo"] === value : boolean
->o?.["foo"] : number | undefined
+>o?.["foo"] : string | number | undefined
 >o : Thing | null
 >"foo" : "foo"
 >value : number
 
-        o;
->o : Thing
-
         o["foo"];
 >o["foo"] : number
 >o : Thing
@@ -736,8 +759,42 @@ function f11(o: Thing | null, value: number) {
 >bar : (() => number) | undefined
 >value : number
 
-        o;
+        o.bar;
+>o.bar : () => number
 >o : Thing
+>bar : () => number
+    }
+    if (o?.foo == value) {
+>o?.foo == value : boolean
+>o?.foo : string | number | undefined
+>o : Thing | null
+>foo : string | number | undefined
+>value : number
+
+        o.foo;
+>o.foo : string | number
+>o : Thing
+>foo : string | number
+    }
+    if (o?.["foo"] == value) {
+>o?.["foo"] == value : boolean
+>o?.["foo"] : string | number | undefined
+>o : Thing | null
+>"foo" : "foo"
+>value : number
+
+        o["foo"];
+>o["foo"] : string | number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (o?.bar() == value) {
+>o?.bar() == value : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | null
+>bar : (() => number) | undefined
+>value : number
 
         o.bar;
 >o.bar : () => number
@@ -753,14 +810,11 @@ function f12(o: Thing | undefined, value: number | undefined) {
 
     if (o?.foo === value) {
 >o?.foo === value : boolean
->o?.foo : number | undefined
+>o?.foo : string | number | undefined
 >o : Thing | undefined
->foo : number | undefined
+>foo : string | number | undefined
 >value : number | undefined
 
-        o;
->o : Thing | undefined
-
         o.foo;  // Error
 >o.foo : number
 >o : Thing | undefined
@@ -768,17 +822,96 @@ function f12(o: Thing | undefined, value: number | undefined) {
     }
     if (o?.["foo"] === value) {
 >o?.["foo"] === value : boolean
->o?.["foo"] : number | undefined
+>o?.["foo"] : string | number | undefined
 >o : Thing | undefined
 >"foo" : "foo"
 >value : number | undefined
 
-        o;
+        o["foo"];  // Error
+>o["foo"] : number
+>o : Thing | undefined
+>"foo" : "foo"
+    }
+    if (o?.bar() === value) {
+>o?.bar() === value : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>value : number | undefined
+
+        o.bar;  // Error
+>o.bar : () => number
+>o : Thing | undefined
+>bar : () => number
+    }
+    if (o?.foo == value) {
+>o?.foo == value : boolean
+>o?.foo : string | number | undefined
+>o : Thing | undefined
+>foo : string | number | undefined
+>value : number | undefined
+
+        o.foo;  // Error
+>o.foo : number
 >o : Thing | undefined
+>foo : number
+    }
+    if (o?.["foo"] == value) {
+>o?.["foo"] == value : boolean
+>o?.["foo"] : string | number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>value : number | undefined
 
         o["foo"];  // Error
 >o["foo"] : number
 >o : Thing | undefined
+>"foo" : "foo"
+    }
+    if (o?.bar() == value) {
+>o?.bar() == value : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>value : number | undefined
+
+        o.bar;  // Error
+>o.bar : () => number
+>o : Thing | undefined
+>bar : () => number
+    }
+}
+
+function f12a(o: Thing | undefined, value: number | null) {
+>f12a : (o: Thing | undefined, value: number | null) => void
+>o : Thing | undefined
+>value : number | null
+>null : null
+
+    if (o?.foo === value) {
+>o?.foo === value : boolean
+>o?.foo : string | number | undefined
+>o : Thing | undefined
+>foo : string | number | undefined
+>value : number | null
+
+        o.foo;
+>o.foo : number
+>o : Thing
+>foo : number
+    }
+    if (o?.["foo"] === value) {
+>o?.["foo"] === value : boolean
+>o?.["foo"] : string | number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>value : number | null
+
+        o["foo"];
+>o["foo"] : number
+>o : Thing
 >"foo" : "foo"
     }
     if (o?.bar() === value) {
@@ -787,10 +920,44 @@ function f12(o: Thing | undefined, value: number | undefined) {
 >o?.bar : (() => number) | undefined
 >o : Thing | undefined
 >bar : (() => number) | undefined
->value : number | undefined
+>value : number | null
 
-        o;
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+    if (o?.foo == value) {
+>o?.foo == value : boolean
+>o?.foo : string | number | undefined
 >o : Thing | undefined
+>foo : string | number | undefined
+>value : number | null
+
+        o.foo;  // Error
+>o.foo : number
+>o : Thing | undefined
+>foo : number
+    }
+    if (o?.["foo"] == value) {
+>o?.["foo"] == value : boolean
+>o?.["foo"] : string | number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>value : number | null
+
+        o["foo"];  // Error
+>o["foo"] : number
+>o : Thing | undefined
+>"foo" : "foo"
+    }
+    if (o?.bar() == value) {
+>o?.bar() == value : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>value : number | null
 
         o.bar;  // Error
 >o.bar : () => number
@@ -805,31 +972,25 @@ function f13(o: Thing | undefined) {
 
     if (o?.foo !== undefined) {
 >o?.foo !== undefined : boolean
->o?.foo : number | undefined
+>o?.foo : string | number | undefined
 >o : Thing | undefined
->foo : number | undefined
+>foo : string | number | undefined
 >undefined : undefined
 
-        o;
->o : Thing
-
         o.foo;
->o.foo : number
+>o.foo : string | number
 >o : Thing
->foo : number
+>foo : string | number
     }
     if (o?.["foo"] !== undefined) {
 >o?.["foo"] !== undefined : boolean
->o?.["foo"] : number | undefined
+>o?.["foo"] : string | number | undefined
 >o : Thing | undefined
 >"foo" : "foo"
 >undefined : undefined
 
-        o;
->o : Thing
-
         o["foo"];
->o["foo"] : number
+>o["foo"] : string | number
 >o : Thing
 >"foo" : "foo"
     }
@@ -841,8 +1002,122 @@ function f13(o: Thing | undefined) {
 >bar : (() => number) | undefined
 >undefined : undefined
 
-        o;
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+    if (o?.foo != undefined) {
+>o?.foo != undefined : boolean
+>o?.foo : string | number | undefined
+>o : Thing | undefined
+>foo : string | number | undefined
+>undefined : undefined
+
+        o.foo;
+>o.foo : string | number
+>o : Thing
+>foo : string | number
+    }
+    if (o?.["foo"] != undefined) {
+>o?.["foo"] != undefined : boolean
+>o?.["foo"] : string | number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>undefined : undefined
+
+        o["foo"];
+>o["foo"] : string | number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (o?.bar() != undefined) {
+>o?.bar() != undefined : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>undefined : undefined
+
+        o.bar;
+>o.bar : () => number
 >o : Thing
+>bar : () => number
+    }
+}
+
+function f13a(o: Thing | undefined) {
+>f13a : (o: Thing | undefined) => void
+>o : Thing | undefined
+
+    if (o?.foo !== null) {
+>o?.foo !== null : boolean
+>o?.foo : string | number | undefined
+>o : Thing | undefined
+>foo : string | number | undefined
+>null : null
+
+        o.foo;  // Error
+>o.foo : string | number
+>o : Thing | undefined
+>foo : string | number
+    }
+    if (o?.["foo"] !== null) {
+>o?.["foo"] !== null : boolean
+>o?.["foo"] : string | number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>null : null
+
+        o["foo"];  // Error
+>o["foo"] : string | number
+>o : Thing | undefined
+>"foo" : "foo"
+    }
+    if (o?.bar() !== null) {
+>o?.bar() !== null : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>null : null
+
+        o.bar;  // Error
+>o.bar : () => number
+>o : Thing | undefined
+>bar : () => number
+    }
+    if (o?.foo != null) {
+>o?.foo != null : boolean
+>o?.foo : string | number | undefined
+>o : Thing | undefined
+>foo : string | number | undefined
+>null : null
+
+        o.foo;
+>o.foo : string | number
+>o : Thing
+>foo : string | number
+    }
+    if (o?.["foo"] != null) {
+>o?.["foo"] != null : boolean
+>o?.["foo"] : string | number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>null : null
+
+        o["foo"];
+>o["foo"] : string | number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (o?.bar() != null) {
+>o?.bar() != null : boolean
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>null : null
 
         o.bar;
 >o.bar : () => number
@@ -858,31 +1133,25 @@ function f14(o: Thing | null) {
 
     if (o?.foo !== undefined) {
 >o?.foo !== undefined : boolean
->o?.foo : number | undefined
+>o?.foo : string | number | undefined
 >o : Thing | null
->foo : number | undefined
+>foo : string | number | undefined
 >undefined : undefined
 
-        o;
->o : Thing
-
         o.foo;
->o.foo : number
+>o.foo : string | number
 >o : Thing
->foo : number
+>foo : string | number
     }
     if (o?.["foo"] !== undefined) {
 >o?.["foo"] !== undefined : boolean
->o?.["foo"] : number | undefined
+>o?.["foo"] : string | number | undefined
 >o : Thing | null
 >"foo" : "foo"
 >undefined : undefined
 
-        o;
->o : Thing
-
         o["foo"];
->o["foo"] : number
+>o["foo"] : string | number
 >o : Thing
 >"foo" : "foo"
     }
@@ -894,13 +1163,127 @@ function f14(o: Thing | null) {
 >bar : (() => number) | undefined
 >undefined : undefined
 
-        o;
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+}
+
+function f20(o: Thing | undefined) {
+>f20 : (o: Thing | undefined) => void
+>o : Thing | undefined
+
+    if (typeof o?.foo === "number") {
+>typeof o?.foo === "number" : boolean
+>typeof o?.foo : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>o?.foo : string | number | undefined
+>o : Thing | undefined
+>foo : string | number | undefined
+>"number" : "number"
+
+        o.foo;
+>o.foo : number
 >o : Thing
+>foo : number
+    }
+    if (typeof o?.["foo"] === "number") {
+>typeof o?.["foo"] === "number" : boolean
+>typeof o?.["foo"] : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>o?.["foo"] : string | number | undefined
+>o : Thing | undefined
+>"foo" : "foo"
+>"number" : "number"
+
+        o["foo"];
+>o["foo"] : number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (typeof o?.bar() === "number") {
+>typeof o?.bar() === "number" : boolean
+>typeof o?.bar() : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | undefined
+>bar : (() => number) | undefined
+>"number" : "number"
 
         o.bar;
 >o.bar : () => number
 >o : Thing
 >bar : () => number
     }
+    if (o?.baz instanceof Error) {
+>o?.baz instanceof Error : boolean
+>o?.baz : object | undefined
+>o : Thing | undefined
+>baz : object | undefined
+>Error : ErrorConstructor
+
+        o.baz;
+>o.baz : Error
+>o : Thing
+>baz : Error
+    }
+}
+
+function f21(o: Thing | null) {
+>f21 : (o: Thing | null) => void
+>o : Thing | null
+>null : null
+
+    if (typeof o?.foo === "number") {
+>typeof o?.foo === "number" : boolean
+>typeof o?.foo : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>o?.foo : string | number | undefined
+>o : Thing | null
+>foo : string | number | undefined
+>"number" : "number"
+
+        o.foo;
+>o.foo : number
+>o : Thing
+>foo : number
+    }
+    if (typeof o?.["foo"] === "number") {
+>typeof o?.["foo"] === "number" : boolean
+>typeof o?.["foo"] : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>o?.["foo"] : string | number | undefined
+>o : Thing | null
+>"foo" : "foo"
+>"number" : "number"
+
+        o["foo"];
+>o["foo"] : number
+>o : Thing
+>"foo" : "foo"
+    }
+    if (typeof o?.bar() === "number") {
+>typeof o?.bar() === "number" : boolean
+>typeof o?.bar() : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>o?.bar() : number | undefined
+>o?.bar : (() => number) | undefined
+>o : Thing | null
+>bar : (() => number) | undefined
+>"number" : "number"
+
+        o.bar;
+>o.bar : () => number
+>o : Thing
+>bar : () => number
+    }
+    if (o?.baz instanceof Error) {
+>o?.baz instanceof Error : boolean
+>o?.baz : object | undefined
+>o : Thing | null
+>baz : object | undefined
+>Error : ErrorConstructor
+
+        o.baz;
+>o.baz : Error
+>o : Thing
+>baz : Error
+    }
 }