Nullish coalescing operator

src/compiler/transformers/esnext.ts

@@ -1,6 +1,10 @@
 /*@internal*/
 namespace ts {
     export function transformESNext(context: TransformationContext) {
+        const {
+            hoistVariableDeclaration,
+        } = context;
+
         return chainBundle(transformSourceFile);
 
         function transformSourceFile(node: SourceFile) {
@@ -40,7 +44,7 @@ namespace ts {
             const expressions: Expression[] = [];
             let left = visitNode(node.left, visitor, isExpression);
             if (!isIdentifier(left)) {
-                const temp = createTempVariable(/*recordTempVariable*/ undefined);
+                const temp = createTempVariable(hoistVariableDeclaration);
                 expressions.push(createAssignment(temp, left));
                 left = temp;
             }

tests/baselines/reference/nullishCoalescingOperator3.js

@@ -11,5 +11,6 @@ const aa1 = a1 ?? a2 ?? a3 ?? a4 ?? a5 ?? a6 ?? 'whatever'
 
 
 //// [nullishCoalescingOperator3.js]
+var _a, _b, _c, _d, _e;
 "use strict";
-var aa1 = (_a = (_b = (_c = (_d = (_e = typeof a1 !== "undefined" && a1 !== null ? a1 : a2, _e !== void 0 && _e !== null ? _e : a3), _d !== void 0 && _d !== null ? _d : a4), _c !== void 0 && _c !== null ? _c : a5), _b !== void 0 && _b !== null ? _b : a6), _a !== void 0 && _a !== null ? _a : 'whatever');
+var aa1 = (_e = (_d = (_c = (_b = (_a = typeof a1 !== "undefined" && a1 !== null ? a1 : a2, _a !== void 0 && _a !== null ? _a : a3), _b !== void 0 && _b !== null ? _b : a4), _c !== void 0 && _c !== null ? _c : a5), _d !== void 0 && _d !== null ? _d : a6), _e !== void 0 && _e !== null ? _e : 'whatever');

tests/baselines/reference/nullishCoalescingOperator5.js

@@ -41,6 +41,7 @@ a && (b ?? c);
 
 
 //// [nullishCoalescingOperator5.js]
+var _a, _b, _c, _d;
 "use strict";
 // should be a syntax error
 typeof a !== "undefined" && a !== null ? a : b || c;

tests/baselines/reference/nullishCoalescingOperator8.js

@@ -0,0 +1,16 @@
+//// [nullishCoalescingOperator8.ts]
+declare const a: { p: string | undefined, m(): string | undefined };
+declare const b: { p: string | undefined, m(): string | undefined };
+
+const n1 = a.p ?? "default";
+const n2 = a.m() ?? "default";
+const n3 = a.m() ?? b.p ?? b.m() ?? "default";;
+
+
+//// [nullishCoalescingOperator8.js]
+var _a, _b, _c, _d, _e;
+"use strict";
+var n1 = (_a = a.p, _a !== void 0 && _a !== null ? _a : "default");
+var n2 = (_b = a.m(), _b !== void 0 && _b !== null ? _b : "default");
+var n3 = (_e = (_d = (_c = a.m(), _c !== void 0 && _c !== null ? _c : b.p), _d !== void 0 && _d !== null ? _d : b.m()), _e !== void 0 && _e !== null ? _e : "default");
+;

tests/baselines/reference/nullishCoalescingOperator8.symbols

@@ -0,0 +1,35 @@
+=== tests/cases/conformance/expressions/nullishCoalescingOperator/nullishCoalescingOperator8.ts ===
+declare const a: { p: string | undefined, m(): string | undefined };
+>a : Symbol(a, Decl(nullishCoalescingOperator8.ts, 0, 13))
+>p : Symbol(p, Decl(nullishCoalescingOperator8.ts, 0, 18))
+>m : Symbol(m, Decl(nullishCoalescingOperator8.ts, 0, 41))
+
+declare const b: { p: string | undefined, m(): string | undefined };
+>b : Symbol(b, Decl(nullishCoalescingOperator8.ts, 1, 13))
+>p : Symbol(p, Decl(nullishCoalescingOperator8.ts, 1, 18))
+>m : Symbol(m, Decl(nullishCoalescingOperator8.ts, 1, 41))
+
+const n1 = a.p ?? "default";
+>n1 : Symbol(n1, Decl(nullishCoalescingOperator8.ts, 3, 5))
+>a.p : Symbol(p, Decl(nullishCoalescingOperator8.ts, 0, 18))
+>a : Symbol(a, Decl(nullishCoalescingOperator8.ts, 0, 13))
+>p : Symbol(p, Decl(nullishCoalescingOperator8.ts, 0, 18))
+
+const n2 = a.m() ?? "default";
+>n2 : Symbol(n2, Decl(nullishCoalescingOperator8.ts, 4, 5))
+>a.m : Symbol(m, Decl(nullishCoalescingOperator8.ts, 0, 41))
+>a : Symbol(a, Decl(nullishCoalescingOperator8.ts, 0, 13))
+>m : Symbol(m, Decl(nullishCoalescingOperator8.ts, 0, 41))
+
+const n3 = a.m() ?? b.p ?? b.m() ?? "default";;
+>n3 : Symbol(n3, Decl(nullishCoalescingOperator8.ts, 5, 5))
+>a.m : Symbol(m, Decl(nullishCoalescingOperator8.ts, 0, 41))
+>a : Symbol(a, Decl(nullishCoalescingOperator8.ts, 0, 13))
+>m : Symbol(m, Decl(nullishCoalescingOperator8.ts, 0, 41))
+>b.p : Symbol(p, Decl(nullishCoalescingOperator8.ts, 1, 18))
+>b : Symbol(b, Decl(nullishCoalescingOperator8.ts, 1, 13))
+>p : Symbol(p, Decl(nullishCoalescingOperator8.ts, 1, 18))
+>b.m : Symbol(m, Decl(nullishCoalescingOperator8.ts, 1, 41))
+>b : Symbol(b, Decl(nullishCoalescingOperator8.ts, 1, 13))
+>m : Symbol(m, Decl(nullishCoalescingOperator8.ts, 1, 41))
+

tests/baselines/reference/nullishCoalescingOperator8.types

@@ -0,0 +1,46 @@
+=== tests/cases/conformance/expressions/nullishCoalescingOperator/nullishCoalescingOperator8.ts ===
+declare const a: { p: string | undefined, m(): string | undefined };
+>a : { p: string | undefined; m(): string | undefined; }
+>p : string | undefined
+>m : () => string | undefined
+
+declare const b: { p: string | undefined, m(): string | undefined };
+>b : { p: string | undefined; m(): string | undefined; }
+>p : string | undefined
+>m : () => string | undefined
+
+const n1 = a.p ?? "default";
+>n1 : string
+>a.p ?? "default" : string
+>a.p : string | undefined
+>a : { p: string | undefined; m(): string | undefined; }
+>p : string | undefined
+>"default" : "default"
+
+const n2 = a.m() ?? "default";
+>n2 : string
+>a.m() ?? "default" : string
+>a.m() : string | undefined
+>a.m : () => string | undefined
+>a : { p: string | undefined; m(): string | undefined; }
+>m : () => string | undefined
+>"default" : "default"
+
+const n3 = a.m() ?? b.p ?? b.m() ?? "default";;
+>n3 : string
+>a.m() ?? b.p ?? b.m() ?? "default" : string
+>a.m() ?? b.p ?? b.m() : string | undefined
+>a.m() ?? b.p : string | undefined
+>a.m() : string | undefined
+>a.m : () => string | undefined
+>a : { p: string | undefined; m(): string | undefined; }
+>m : () => string | undefined
+>b.p : string | undefined
+>b : { p: string | undefined; m(): string | undefined; }
+>p : string | undefined
+>b.m() : string | undefined
+>b.m : () => string | undefined
+>b : { p: string | undefined; m(): string | undefined; }
+>m : () => string | undefined
+>"default" : "default"
+

tests/baselines/reference/nullishCoalescingOperator_esnext.js

@@ -18,7 +18,24 @@ const aa5 = a5 ?? 'whatever'
 const aa6 = a6 ?? 'whatever'
 const aa7 = a7 ?? 'whatever'
 const aa8 = a8 ?? 'whatever'
-const aa9 = a9 ?? 'whatever'
+const aa9 = a9 ?? 'whatever'
+
+
+declare let a: any, b: any, c: any;
+
+let x1 = (a ?? b as any) || c;
+let x2 = c || (a ?? b as any);
+let x3 = ((a ?? b) as any) || c;
+let x4 = c || ((a ?? b) as any);
+let x5 = (a ?? b) as any || c;
+let x6 = c || (a ?? b) as any;
+
+let y1 = (a ?? b as any) && c;
+let y2 = c && (a ?? b as any);
+let y3 = ((a ?? b) as any) && c;
+let y4 = c && ((a ?? b) as any);
+let y5 = (a ?? b) as any && c;
+let y6 = c && (a ?? b) as any;
 
 //// [nullishCoalescingOperator_esnext.js]
 "use strict";
@@ -31,3 +48,15 @@ const aa6 = a6 ?? 'whatever';
 const aa7 = a7 ?? 'whatever';
 const aa8 = a8 ?? 'whatever';
 const aa9 = a9 ?? 'whatever';
+let x1 = (a ?? b) || c;
+let x2 = c || (a ?? b);
+let x3 = (a ?? b) || c;
+let x4 = c || (a ?? b);
+let x5 = (a ?? b) || c;
+let x6 = c || (a ?? b);
+let y1 = (a ?? b) && c;
+let y2 = c && (a ?? b);
+let y3 = (a ?? b) && c;
+let y4 = c && (a ?? b);
+let y5 = (a ?? b) && c;
+let y6 = c && (a ?? b);

tests/baselines/reference/nullishCoalescingOperator_esnext.symbols

@@ -63,3 +63,81 @@ const aa9 = a9 ?? 'whatever'
 >aa9 : Symbol(aa9, Decl(nullishCoalescingOperator_esnext.ts, 19, 5))
 >a9 : Symbol(a9, Decl(nullishCoalescingOperator_esnext.ts, 8, 13))
 
+
+declare let a: any, b: any, c: any;
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+
+let x1 = (a ?? b as any) || c;
+>x1 : Symbol(x1, Decl(nullishCoalescingOperator_esnext.ts, 24, 3))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+
+let x2 = c || (a ?? b as any);
+>x2 : Symbol(x2, Decl(nullishCoalescingOperator_esnext.ts, 25, 3))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+
+let x3 = ((a ?? b) as any) || c;
+>x3 : Symbol(x3, Decl(nullishCoalescingOperator_esnext.ts, 26, 3))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+
+let x4 = c || ((a ?? b) as any);
+>x4 : Symbol(x4, Decl(nullishCoalescingOperator_esnext.ts, 27, 3))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+
+let x5 = (a ?? b) as any || c;
+>x5 : Symbol(x5, Decl(nullishCoalescingOperator_esnext.ts, 28, 3))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+
+let x6 = c || (a ?? b) as any;
+>x6 : Symbol(x6, Decl(nullishCoalescingOperator_esnext.ts, 29, 3))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+
+let y1 = (a ?? b as any) && c;
+>y1 : Symbol(y1, Decl(nullishCoalescingOperator_esnext.ts, 31, 3))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+
+let y2 = c && (a ?? b as any);
+>y2 : Symbol(y2, Decl(nullishCoalescingOperator_esnext.ts, 32, 3))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+
+let y3 = ((a ?? b) as any) && c;
+>y3 : Symbol(y3, Decl(nullishCoalescingOperator_esnext.ts, 33, 3))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+
+let y4 = c && ((a ?? b) as any);
+>y4 : Symbol(y4, Decl(nullishCoalescingOperator_esnext.ts, 34, 3))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+
+let y5 = (a ?? b) as any && c;
+>y5 : Symbol(y5, Decl(nullishCoalescingOperator_esnext.ts, 35, 3))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+
+let y6 = c && (a ?? b) as any;
+>y6 : Symbol(y6, Decl(nullishCoalescingOperator_esnext.ts, 36, 3))
+>c : Symbol(c, Decl(nullishCoalescingOperator_esnext.ts, 22, 27))
+>a : Symbol(a, Decl(nullishCoalescingOperator_esnext.ts, 22, 11))
+>b : Symbol(b, Decl(nullishCoalescingOperator_esnext.ts, 22, 19))
+

tests/baselines/reference/nullishCoalescingOperator_esnext.types

@@ -92,3 +92,133 @@ const aa9 = a9 ?? 'whatever'
 >a9 : any
 >'whatever' : "whatever"
 
+
+declare let a: any, b: any, c: any;
+>a : any
+>b : any
+>c : any
+
+let x1 = (a ?? b as any) || c;
+>x1 : any
+>(a ?? b as any) || c : any
+>(a ?? b as any) : any
+>a ?? b as any : any
+>a : any
+>b as any : any
+>b : any
+>c : any
+
+let x2 = c || (a ?? b as any);
+>x2 : any
+>c || (a ?? b as any) : any
+>c : any
+>(a ?? b as any) : any
+>a ?? b as any : any
+>a : any
+>b as any : any
+>b : any
+
+let x3 = ((a ?? b) as any) || c;
+>x3 : any
+>((a ?? b) as any) || c : any
+>((a ?? b) as any) : any
+>(a ?? b) as any : any
+>(a ?? b) : any
+>a ?? b : any
+>a : any
+>b : any
+>c : any
+
+let x4 = c || ((a ?? b) as any);
+>x4 : any
+>c || ((a ?? b) as any) : any
+>c : any
+>((a ?? b) as any) : any
+>(a ?? b) as any : any
+>(a ?? b) : any
+>a ?? b : any
+>a : any
+>b : any
+
+let x5 = (a ?? b) as any || c;
+>x5 : any
+>(a ?? b) as any || c : any
+>(a ?? b) as any : any
+>(a ?? b) : any
+>a ?? b : any
+>a : any
+>b : any
+>c : any
+
+let x6 = c || (a ?? b) as any;
+>x6 : any
+>c || (a ?? b) as any : any
+>c : any
+>(a ?? b) as any : any
+>(a ?? b) : any
+>a ?? b : any
+>a : any
+>b : any
+
+let y1 = (a ?? b as any) && c;
+>y1 : any
+>(a ?? b as any) && c : any
+>(a ?? b as any) : any
+>a ?? b as any : any
+>a : any
+>b as any : any
+>b : any
+>c : any
+
+let y2 = c && (a ?? b as any);
+>y2 : any
+>c && (a ?? b as any) : any
+>c : any
+>(a ?? b as any) : any
+>a ?? b as any : any
+>a : any
+>b as any : any
+>b : any
+
+let y3 = ((a ?? b) as any) && c;
+>y3 : any
+>((a ?? b) as any) && c : any
+>((a ?? b) as any) : any
+>(a ?? b) as any : any
+>(a ?? b) : any
+>a ?? b : any
+>a : any
+>b : any
+>c : any
+
+let y4 = c && ((a ?? b) as any);
+>y4 : any
+>c && ((a ?? b) as any) : any
+>c : any
+>((a ?? b) as any) : any
+>(a ?? b) as any : any
+>(a ?? b) : any
+>a ?? b : any
+>a : any
+>b : any
+
+let y5 = (a ?? b) as any && c;
+>y5 : any
+>(a ?? b) as any && c : any
+>(a ?? b) as any : any
+>(a ?? b) : any
+>a ?? b : any
+>a : any
+>b : any
+>c : any
+
+let y6 = c && (a ?? b) as any;
+>y6 : any
+>c && (a ?? b) as any : any
+>c : any
+>(a ?? b) as any : any
+>(a ?? b) : any
+>a ?? b : any
+>a : any
+>b : any
+