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Andy
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A function should be context-sensitive if its return expression is (microsoft#17697)
* A function should be context-sensitive if its return expression is * Remove outdated comment * Fix typo
1 parent 4c82450 commit fe3a05e

9 files changed

Lines changed: 75 additions & 28 deletions

‎src/compiler/checker.ts‎

Lines changed: 10 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -8405,16 +8405,17 @@ namespace ts {
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if (forEach(node.parameters, p => !getEffectiveTypeAnnotationNode(p))) {
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return true;
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}
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// For arrow functions we now know we're not context sensitive.
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if (node.kind === SyntaxKind.ArrowFunction) {
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return false;
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if (node.kind !== SyntaxKind.ArrowFunction) {
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// If the first parameter is not an explicit 'this' parameter, then the function has
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// an implicit 'this' parameter which is subject to contextual typing.
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const parameter = firstOrUndefined(node.parameters);
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if (!(parameter && parameterIsThisKeyword(parameter))) {
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return true;
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}
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}
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// If the first parameter is not an explicit 'this' parameter, then the function has
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// an implicit 'this' parameter which is subject to contextual typing. Otherwise we
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// know that all parameters (including 'this') have type annotations and nothing is
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// subject to contextual typing.
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const parameter = firstOrUndefined(node.parameters);
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return !(parameter && parameterIsThisKeyword(parameter));
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// TODO(anhans): A block should be context-sensitive if it has a context-sensitive return value.
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return node.body.kind === SyntaxKind.Block ? false : isContextSensitive(node.body);
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}
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function isContextSensitiveFunctionOrObjectLiteralMethod(func: Node): func is FunctionExpression | ArrowFunction | MethodDeclaration {

‎tests/baselines/reference/contextualTypingFunctionReturningFunction2.js‎

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@@ -0,0 +1,9 @@
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//// [contextualTypingFunctionReturningFunction2.ts]
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declare function f(n: number): void;
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declare function f(cb: () => (n: number) => number): void;
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f(() => n => n);
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//// [contextualTypingFunctionReturningFunction2.js]
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f(function () { return function (n) { return n; }; });

‎tests/baselines/reference/contextualTypingFunctionReturningFunction2.symbols‎

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@@ -0,0 +1,15 @@
1+
=== tests/cases/compiler/contextualTypingFunctionReturningFunction2.ts ===
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declare function f(n: number): void;
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>f : Symbol(f, Decl(contextualTypingFunctionReturningFunction2.ts, 0, 0), Decl(contextualTypingFunctionReturningFunction2.ts, 0, 36))
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>n : Symbol(n, Decl(contextualTypingFunctionReturningFunction2.ts, 0, 19))
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declare function f(cb: () => (n: number) => number): void;
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>f : Symbol(f, Decl(contextualTypingFunctionReturningFunction2.ts, 0, 0), Decl(contextualTypingFunctionReturningFunction2.ts, 0, 36))
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>cb : Symbol(cb, Decl(contextualTypingFunctionReturningFunction2.ts, 1, 19))
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>n : Symbol(n, Decl(contextualTypingFunctionReturningFunction2.ts, 1, 30))
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f(() => n => n);
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>f : Symbol(f, Decl(contextualTypingFunctionReturningFunction2.ts, 0, 0), Decl(contextualTypingFunctionReturningFunction2.ts, 0, 36))
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>n : Symbol(n, Decl(contextualTypingFunctionReturningFunction2.ts, 3, 7))
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>n : Symbol(n, Decl(contextualTypingFunctionReturningFunction2.ts, 3, 7))
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‎tests/baselines/reference/contextualTypingFunctionReturningFunction2.types‎

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@@ -0,0 +1,18 @@
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=== tests/cases/compiler/contextualTypingFunctionReturningFunction2.ts ===
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declare function f(n: number): void;
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>f : { (n: number): void; (cb: () => (n: number) => number): void; }
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>n : number
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declare function f(cb: () => (n: number) => number): void;
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>f : { (n: number): void; (cb: () => (n: number) => number): void; }
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>cb : () => (n: number) => number
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>n : number
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f(() => n => n);
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>f(() => n => n) : void
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>f : { (n: number): void; (cb: () => (n: number) => number): void; }
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>() => n => n : () => (n: number) => number
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>n => n : (n: number) => number
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>n : number
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>n : number
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‎tests/baselines/reference/contextualTypingWithFixedTypeParameters1.errors.txt‎

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,15 @@
11
tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(2,22): error TS2339: Property 'foo' does not exist on type 'string'.
2-
tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(3,32): error TS2339: Property 'foo' does not exist on type 'string'.
3-
tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(3,38): error TS2345: Argument of type '1' is not assignable to parameter of type 'string'.
2+
tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(3,32): error TS2339: Property 'foo' does not exist on type '""'.
3+
tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts(3,38): error TS2345: Argument of type '1' is not assignable to parameter of type '""'.
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55

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==== tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts (3 errors) ====
77
var f10: <T>(x: T, b: () => (a: T) => void, y: T) => T;
8-
f10('', () => a => a.foo, ''); // a is string
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f10('', () => a => a.foo, ''); // a is ""
99
~~~
1010
!!! error TS2339: Property 'foo' does not exist on type 'string'.
1111
var r9 = f10('', () => (a => a.foo), 1); // error
1212
~~~
13-
!!! error TS2339: Property 'foo' does not exist on type 'string'.
13+
!!! error TS2339: Property 'foo' does not exist on type '""'.
1414
~
15-
!!! error TS2345: Argument of type '1' is not assignable to parameter of type 'string'.
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!!! error TS2345: Argument of type '1' is not assignable to parameter of type '""'.

‎tests/baselines/reference/contextualTypingWithFixedTypeParameters1.js‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,9 @@
11
//// [contextualTypingWithFixedTypeParameters1.ts]
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var f10: <T>(x: T, b: () => (a: T) => void, y: T) => T;
3-
f10('', () => a => a.foo, ''); // a is string
3+
f10('', () => a => a.foo, ''); // a is ""
44
var r9 = f10('', () => (a => a.foo), 1); // error
55

66
//// [contextualTypingWithFixedTypeParameters1.js]
77
var f10;
8-
f10('', function () { return function (a) { return a.foo; }; }, ''); // a is string
8+
f10('', function () { return function (a) { return a.foo; }; }, ''); // a is ""
99
var r9 = f10('', function () { return (function (a) { return a.foo; }); }, 1); // error

‎tests/cases/compiler/contextualTypingFunctionReturningFunction.ts‎

Lines changed: 11 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,11 @@
1-
interface I {
2-
a(s: string): void;
3-
b(): (n: number) => void;
4-
}
5-
6-
declare function f(i: I): void;
7-
8-
f({
9-
a: s => {},
10-
b: () => n => {},
11-
});
1+
interface I {
2+
a(s: string): void;
3+
b(): (n: number) => void;
4+
}
5+
6+
declare function f(i: I): void;
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f({
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a: s => {},
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b: () => n => {},
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});

‎tests/cases/compiler/contextualTypingFunctionReturningFunction2.ts‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,4 @@
1+
declare function f(n: number): void;
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declare function f(cb: () => (n: number) => number): void;
3+
4+
f(() => n => n);

‎tests/cases/compiler/contextualTypingWithFixedTypeParameters1.ts‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,3 @@
11
var f10: <T>(x: T, b: () => (a: T) => void, y: T) => T;
2-
f10('', () => a => a.foo, ''); // a is string
2+
f10('', () => a => a.foo, ''); // a is ""
33
var r9 = f10('', () => (a => a.foo), 1); // error

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