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Generic functions are never context sensitive #37811

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Merged
merged 2 commits into from
Apr 6, 2020
Merged

Generic functions are never context sensitive #37811

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ef60613
Functions with type parameters are never contextsensitive
ahejlsberg Apr 6, 2020
2cb8b25
Add tests
ahejlsberg Apr 6, 2020
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2 changes: 1 addition & 1 deletion src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -14251,7 +14251,7 @@ namespace ts {

function hasContextSensitiveReturnExpression(node: FunctionLikeDeclaration) {
// TODO(anhans): A block should be context-sensitive if it has a context-sensitive return value.
return !getEffectiveReturnTypeNode(node) && !!node.body && node.body.kind !== SyntaxKind.Block && isContextSensitive(node.body);
return !node.typeParameters && !getEffectiveReturnTypeNode(node) && !!node.body && node.body.kind !== SyntaxKind.Block && isContextSensitive(node.body);
}

function isContextSensitiveFunctionOrObjectLiteralMethod(func: Node): func is FunctionExpression | ArrowFunction | MethodDeclaration {
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13 changes: 13 additions & 0 deletions tests/baselines/reference/genericFunctionsNotContextSensitive.js
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@@ -0,0 +1,13 @@
//// [genericFunctionsNotContextSensitive.ts]
// Repro from #37110

const f = <F extends (...args: any[]) => <G>(x: G) => void>(_: F): F => _;

const a = f(<K extends string>(_: K) => _ => ({})); // <K extends string>(_: K) => <G>(_: G) => {}


//// [genericFunctionsNotContextSensitive.js]
"use strict";
// Repro from #37110
var f = function (_) { return _; };
var a = f(function (_) { return function (_) { return ({}); }; }); // <K extends string>(_: K) => <G>(_: G) => {}
23 changes: 23 additions & 0 deletions tests/baselines/reference/genericFunctionsNotContextSensitive.symbols
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@@ -0,0 +1,23 @@
=== tests/cases/compiler/genericFunctionsNotContextSensitive.ts ===
// Repro from #37110

const f = <F extends (...args: any[]) => <G>(x: G) => void>(_: F): F => _;
>f : Symbol(f, Decl(genericFunctionsNotContextSensitive.ts, 2, 5))
>F : Symbol(F, Decl(genericFunctionsNotContextSensitive.ts, 2, 11))
>args : Symbol(args, Decl(genericFunctionsNotContextSensitive.ts, 2, 22))
>G : Symbol(G, Decl(genericFunctionsNotContextSensitive.ts, 2, 42))
>x : Symbol(x, Decl(genericFunctionsNotContextSensitive.ts, 2, 45))
>G : Symbol(G, Decl(genericFunctionsNotContextSensitive.ts, 2, 42))
>_ : Symbol(_, Decl(genericFunctionsNotContextSensitive.ts, 2, 60))
>F : Symbol(F, Decl(genericFunctionsNotContextSensitive.ts, 2, 11))
>F : Symbol(F, Decl(genericFunctionsNotContextSensitive.ts, 2, 11))
>_ : Symbol(_, Decl(genericFunctionsNotContextSensitive.ts, 2, 60))

const a = f(<K extends string>(_: K) => _ => ({})); // <K extends string>(_: K) => <G>(_: G) => {}
>a : Symbol(a, Decl(genericFunctionsNotContextSensitive.ts, 4, 5))
>f : Symbol(f, Decl(genericFunctionsNotContextSensitive.ts, 2, 5))
>K : Symbol(K, Decl(genericFunctionsNotContextSensitive.ts, 4, 13))
>_ : Symbol(_, Decl(genericFunctionsNotContextSensitive.ts, 4, 31))
>K : Symbol(K, Decl(genericFunctionsNotContextSensitive.ts, 4, 13))
>_ : Symbol(_, Decl(genericFunctionsNotContextSensitive.ts, 4, 39))

22 changes: 22 additions & 0 deletions tests/baselines/reference/genericFunctionsNotContextSensitive.types
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@@ -0,0 +1,22 @@
=== tests/cases/compiler/genericFunctionsNotContextSensitive.ts ===
// Repro from #37110

const f = <F extends (...args: any[]) => <G>(x: G) => void>(_: F): F => _;
>f : <F extends (...args: any[]) => <G>(x: G) => void>(_: F) => F
><F extends (...args: any[]) => <G>(x: G) => void>(_: F): F => _ : <F extends (...args: any[]) => <G>(x: G) => void>(_: F) => F
>args : any[]
>x : G
>_ : F
>_ : F

const a = f(<K extends string>(_: K) => _ => ({})); // <K extends string>(_: K) => <G>(_: G) => {}
>a : <K extends string>(_: K) => <G>(_: G) => {}
>f(<K extends string>(_: K) => _ => ({})) : <K extends string>(_: K) => <G>(_: G) => {}
>f : <F extends (...args: any[]) => <G>(x: G) => void>(_: F) => F
><K extends string>(_: K) => _ => ({}) : <K extends string>(_: K) => <G>(_: G) => {}
>_ : K
>_ => ({}) : <G>(_: G) => {}
>_ : G
>({}) : {}
>{} : {}

7 changes: 7 additions & 0 deletions tests/cases/compiler/genericFunctionsNotContextSensitive.ts
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@@ -0,0 +1,7 @@
// @strict: true

// Repro from #37110

const f = <F extends (...args: any[]) => <G>(x: G) => void>(_: F): F => _;

const a = f(<K extends string>(_: K) => _ => ({})); // <K extends string>(_: K) => <G>(_: G) => {}