Strict, but only on true side

src/compiler/parser.ts

@@ -4369,7 +4369,7 @@ namespace ts {
             }
 
             // It wasn't an assignment or a lambda.  This is a conditional expression:
-            return parseConditionalExpressionRest(expr, pos);
+            return parseConditionalExpressionRest(expr, pos, disallowReturnTypeInArrowFunction);
         }
 
         function isYieldExpression(): boolean {
@@ -4788,7 +4788,7 @@ namespace ts {
             return node;
         }
 
-        function parseConditionalExpressionRest(leftOperand: Expression, pos: number): Expression {
+        function parseConditionalExpressionRest(leftOperand: Expression, pos: number, disallowReturnTypeInArrowFunction: boolean): Expression {
             // Note: we are passed in an expression which was produced from parseBinaryExpressionOrHigher.
             const questionToken = parseOptionalToken(SyntaxKind.QuestionToken);
             if (!questionToken) {
@@ -4805,7 +4805,7 @@ namespace ts {
                     doOutsideOfContext(disallowInAndDecoratorContext, () => parseAssignmentExpressionOrHigher(/*disallowReturnTypeInArrowFunction*/ true)),
                     colonToken = parseExpectedToken(SyntaxKind.ColonToken),
                     nodeIsPresent(colonToken)
-                        ? parseAssignmentExpressionOrHigher(/*disallowReturnTypeInArrowFunction*/ true)
+                        ? parseAssignmentExpressionOrHigher(disallowReturnTypeInArrowFunction) // inherit disallowReturnTypeInArrowFunction in false side
                         : createMissingNode(SyntaxKind.Identifier, /*reportAtCurrentPosition*/ false, Diagnostics._0_expected, tokenToString(SyntaxKind.ColonToken))
                 ),
                 pos

tests/baselines/reference/parserArrowFunctionExpression10.errors.txt

@@ -1,20 +1,17 @@
 tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts(1,1): error TS2304: Cannot find name 'a'.
 tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts(1,6): error TS2304: Cannot find name 'b'.
-tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts(1,17): error TS2304: Cannot find name 'd'.
-tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts(1,20): error TS1005: ';' expected.
+tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts(1,22): error TS2304: Cannot find name 'e'.
 tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts(1,27): error TS2304: Cannot find name 'f'.
 
 
-==== tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts (5 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts (4 errors) ====
     a ? (b) : c => (d) : e => f
     ~
 !!! error TS2304: Cannot find name 'a'.
          ~
 !!! error TS2304: Cannot find name 'b'.
-                    ~
-!!! error TS2304: Cannot find name 'd'.
-                       ~
-!!! error TS1005: ';' expected.
+                         ~
+!!! error TS2304: Cannot find name 'e'.
                               ~
 !!! error TS2304: Cannot find name 'f'.
 

tests/baselines/reference/parserArrowFunctionExpression10.js

@@ -3,5 +3,4 @@ a ? (b) : c => (d) : e => f
 
 
 //// [parserArrowFunctionExpression10.js]
-a ? (b) : function (c) { return (d); };
-(function (e) { return f; });
+a ? (b) : function (c) { return function (d) { return f; }; };

tests/baselines/reference/parserArrowFunctionExpression10.symbols

@@ -1,5 +1,6 @@
 === tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts ===
 a ? (b) : c => (d) : e => f
 >c : Symbol(c, Decl(parserArrowFunctionExpression10.ts, 0, 9))
->e : Symbol(e, Decl(parserArrowFunctionExpression10.ts, 0, 20))
+>d : Symbol(d, Decl(parserArrowFunctionExpression10.ts, 0, 16))
+>e : Symbol(e)
 

tests/baselines/reference/parserArrowFunctionExpression10.types

@@ -1,14 +1,12 @@
 === tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression10.ts ===
 a ? (b) : c => (d) : e => f
->a ? (b) : c => (d) : any
+>a ? (b) : c => (d) : e => f : any
 >a : any
 >(b) : any
 >b : any
->c => (d) : (c: any) => any
+>c => (d) : e => f : (c: any) => (d: any) => e
 >c : any
->(d) : any
+>(d) : e => f : (d: any) => e
 >d : any
->e => f : (e: any) => any
->e : any
 >f : any
 

tests/baselines/reference/parserArrowFunctionExpression13.errors.txt

@@ -1,17 +1,11 @@
 tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression13.ts(1,1): error TS2304: Cannot find name 'a'.
 tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression13.ts(1,11): error TS2304: Cannot find name 'a'.
-tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression13.ts(1,18): error TS1109: Expression expected.
-tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression13.ts(1,19): error TS1005: ';' expected.
 
 
-==== tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression13.ts (4 errors) ====
+==== tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression13.ts (2 errors) ====
     a ? () => a() : (): any => null;
     ~
 !!! error TS2304: Cannot find name 'a'.
               ~
 !!! error TS2304: Cannot find name 'a'.
-                     ~
-!!! error TS1109: Expression expected.
-                      ~
-!!! error TS1005: ';' expected.
 

tests/baselines/reference/parserArrowFunctionExpression13.js

@@ -3,5 +3,4 @@ a ? () => a() : (): any => null;
 
 
 //// [parserArrowFunctionExpression13.js]
-a ? function () { return a(); } : ();
-(function (any) { return null; });
+a ? function () { return a(); } : function () { return null; };

tests/baselines/reference/parserArrowFunctionExpression13.symbols

@@ -1,4 +1,4 @@
 === tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression13.ts ===
 a ? () => a() : (): any => null;
->any : Symbol(any, Decl(parserArrowFunctionExpression13.ts, 0, 19))
-
+No type information for this code.
+No type information for this code.

tests/baselines/reference/parserArrowFunctionExpression13.types

@@ -1,13 +1,10 @@
 === tests/cases/conformance/parser/ecmascript5/ArrowFunctionExpressions/parserArrowFunctionExpression13.ts ===
 a ? () => a() : (): any => null;
->a ? () => a() : () : any
+>a ? () => a() : (): any => null : () => any
 >a : any
 >() => a() : () => any
 >a() : any
 >a : any
->() : any
-> : any
->any => null : (any: any) => any
->any : any
+>(): any => null : () => any
 >null : null