Merge pull request #15362 from Microsoft/contextually-type-spread-assignment

Contextually type object spread expressions

Author: sandersn

src/compiler/checker.ts

@@ -12728,6 +12728,8 @@ namespace ts {
                 case SyntaxKind.PropertyAssignment:
                 case SyntaxKind.ShorthandPropertyAssignment:
                     return getContextualTypeForObjectLiteralElement(<ObjectLiteralElementLike>parent);
+                case SyntaxKind.SpreadAssignment:
+                    return getApparentTypeOfContextualType(parent.parent as ObjectLiteralExpression);
                 case SyntaxKind.ArrayLiteralExpression:
                     return getContextualTypeForElementExpression(node);
                 case SyntaxKind.ConditionalExpression:

tests/baselines/reference/contextualTypeObjectSpreadExpression.js

@@ -0,0 +1,19 @@
+//// [contextualTypeObjectSpreadExpression.ts]
+interface I {
+    a: "a";
+}
+let i: I;
+i = { ...{ a: "a" } };
+
+
+//// [contextualTypeObjectSpreadExpression.js]
+var __assign = (this && this.__assign) || Object.assign || function(t) {
+    for (var s, i = 1, n = arguments.length; i < n; i++) {
+        s = arguments[i];
+        for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
+            t[p] = s[p];
+    }
+    return t;
+};
+var i;
+i = __assign({ a: "a" });

tests/baselines/reference/contextualTypeObjectSpreadExpression.symbols

@@ -0,0 +1,15 @@
+=== tests/cases/compiler/contextualTypeObjectSpreadExpression.ts ===
+interface I {
+>I : Symbol(I, Decl(contextualTypeObjectSpreadExpression.ts, 0, 0))
+
+    a: "a";
+>a : Symbol(I.a, Decl(contextualTypeObjectSpreadExpression.ts, 0, 13))
+}
+let i: I;
+>i : Symbol(i, Decl(contextualTypeObjectSpreadExpression.ts, 3, 3))
+>I : Symbol(I, Decl(contextualTypeObjectSpreadExpression.ts, 0, 0))
+
+i = { ...{ a: "a" } };
+>i : Symbol(i, Decl(contextualTypeObjectSpreadExpression.ts, 3, 3))
+>a : Symbol(a, Decl(contextualTypeObjectSpreadExpression.ts, 4, 10))
+

tests/baselines/reference/contextualTypeObjectSpreadExpression.types

@@ -0,0 +1,19 @@
+=== tests/cases/compiler/contextualTypeObjectSpreadExpression.ts ===
+interface I {
+>I : I
+
+    a: "a";
+>a : "a"
+}
+let i: I;
+>i : I
+>I : I
+
+i = { ...{ a: "a" } };
+>i = { ...{ a: "a" } } : { a: "a"; }
+>i : I
+>{ ...{ a: "a" } } : { a: "a"; }
+>{ a: "a" } : { a: "a"; }
+>a : string
+>"a" : "a"
+

tests/baselines/reference/objectSpread.types

@@ -78,11 +78,11 @@ let nested: { a: number, b: boolean, c: string } =
 >c : string
 
     { ...{ a: 3, ...{ b: false, c: 'overriden' } }, c: 'whatever' }
->{ ...{ a: 3, ...{ b: false, c: 'overriden' } }, c: 'whatever' } : { c: string; b: boolean; a: number; }
->{ a: 3, ...{ b: false, c: 'overriden' } } : { b: boolean; c: string; a: number; }
+>{ ...{ a: 3, ...{ b: false, c: 'overriden' } }, c: 'whatever' } : { c: string; b: false; a: number; }
+>{ a: 3, ...{ b: false, c: 'overriden' } } : { b: false; c: string; a: number; }
 >a : number
 >3 : 3
->{ b: false, c: 'overriden' } : { b: boolean; c: string; }
+>{ b: false, c: 'overriden' } : { b: false; c: string; }
 >b : boolean
 >false : false
 >c : string
@@ -148,11 +148,11 @@ let combinedNested: { a: number, b: boolean, c: string, d: string } =
 >d : string
 
     { ...{ a: 4, ...{ b: false, c: 'overriden' } }, d: 'actually new', ...{ a: 5, d: 'maybe new' } }
->{ ...{ a: 4, ...{ b: false, c: 'overriden' } }, d: 'actually new', ...{ a: 5, d: 'maybe new' } } : { a: number; d: string; b: boolean; c: string; }
->{ a: 4, ...{ b: false, c: 'overriden' } } : { b: boolean; c: string; a: number; }
+>{ ...{ a: 4, ...{ b: false, c: 'overriden' } }, d: 'actually new', ...{ a: 5, d: 'maybe new' } } : { a: number; d: string; b: false; c: string; }
+>{ a: 4, ...{ b: false, c: 'overriden' } } : { b: false; c: string; a: number; }
 >a : number
 >4 : 4
->{ b: false, c: 'overriden' } : { b: boolean; c: string; }
+>{ b: false, c: 'overriden' } : { b: false; c: string; }
 >b : boolean
 >false : false
 >c : string
@@ -172,11 +172,11 @@ let combinedNestedChangeType: { a: number, b: boolean, c: number } =
 >c : number
 
     { ...{ a: 1, ...{ b: false, c: 'overriden' } }, c: -1 }
->{ ...{ a: 1, ...{ b: false, c: 'overriden' } }, c: -1 } : { c: number; b: boolean; a: number; }
->{ a: 1, ...{ b: false, c: 'overriden' } } : { b: boolean; c: string; a: number; }
+>{ ...{ a: 1, ...{ b: false, c: 'overriden' } }, c: -1 } : { c: number; b: false; a: number; }
+>{ a: 1, ...{ b: false, c: 'overriden' } } : { b: false; c: string; a: number; }
 >a : number
 >1 : 1
->{ b: false, c: 'overriden' } : { b: boolean; c: string; }
+>{ b: false, c: 'overriden' } : { b: false; c: string; }
 >b : boolean
 >false : false
 >c : string

tests/cases/compiler/contextualTypeObjectSpreadExpression.ts

@@ -0,0 +1,5 @@
+interface I {
+    a: "a";
+}
+let i: I;
+i = { ...{ a: "a" } };