Port PR#60234: Use signature.parameters directly instead of getExpandedParameters

internal/checker/nodebuilderimpl.go

@@ -1693,8 +1693,7 @@ type SignatureToSignatureDeclarationOptions struct {
 func (b *nodeBuilderImpl) signatureToSignatureDeclarationHelper(signature *Signature, kind ast.Kind, options *SignatureToSignatureDeclarationOptions) *ast.Node {
 	var typeParameters []*ast.Node
 
-	expandedParams := b.ch.getExpandedParameters(signature, true /*skipUnionExpanding*/)[0]
-	cleanup := b.enterNewScope(signature.declaration, expandedParams, signature.typeParameters, signature.parameters, signature.mapper)
+	cleanup := b.enterNewScope(signature.declaration, signature.parameters, signature.typeParameters, signature.parameters, signature.mapper)
 	b.ctx.approximateLength += 3
 	// Usually a signature contributes a few more characters than this, but 3 is the minimum
 
@@ -1710,10 +1709,7 @@ func (b *nodeBuilderImpl) signatureToSignatureDeclarationHelper(signature *Signa
 
 	restoreFlags := b.saveRestoreFlags()
 	b.ctx.flags &^= nodebuilder.FlagsSuppressAnyReturnType
-	// If the expanded parameter list had a variadic in a non-trailing position, don't expand it
-	parameters := core.Map(core.IfElse(core.Some(expandedParams, func(p *ast.Symbol) bool {
-		return p != expandedParams[len(expandedParams)-1] && p.CheckFlags&ast.CheckFlagsRestParameter != 0
-	}), signature.parameters, expandedParams), func(parameter *ast.Symbol) *ast.Node {
+	parameters := core.Map(signature.parameters, func(parameter *ast.Symbol) *ast.Node {
 		return b.symbolToParameterDeclaration(parameter, kind == ast.KindConstructor)
 	})
 	var thisParameter *ast.Node

testdata/baselines/reference/submodule/compiler/argumentsSpreadRestIterables(target=es5).types

@@ -24,8 +24,8 @@ declare const itNum: Iterable<number>
 
 ;(function(a, ...rest) {})('', true, ...itNum)
 >(function(a, ...rest) {})('', true, ...itNum) : void
->(function(a, ...rest) {}) : (a: string, rest_0: boolean, ...rest: Iterable<number>[]) => void
->function(a, ...rest) {} : (a: string, rest_0: boolean, ...rest: Iterable<number>[]) => void
+>(function(a, ...rest) {}) : (a: string, ...rest: [boolean, ...Iterable<number>[]]) => void
+>function(a, ...rest) {} : (a: string, ...rest: [boolean, ...Iterable<number>[]]) => void
 >a : string
 >rest : [boolean, ...Iterable<number>[]]
 >'' : ""

testdata/baselines/reference/submodule/compiler/argumentsSpreadRestIterables(target=es5).types.diff

@@ -0,0 +1,13 @@
+--- old.argumentsSpreadRestIterables(target=es5).types
++++ new.argumentsSpreadRestIterables(target=es5).types
+@@= skipped -23, +23 lines =@@
+
+ ;(function(a, ...rest) {})('', true, ...itNum)
+ >(function(a, ...rest) {})('', true, ...itNum) : void
+->(function(a, ...rest) {}) : (a: string, rest_0: boolean, ...rest: Iterable<number>[]) => void
+->function(a, ...rest) {} : (a: string, rest_0: boolean, ...rest: Iterable<number>[]) => void
++>(function(a, ...rest) {}) : (a: string, ...rest: [boolean, ...Iterable<number>[]]) => void
++>function(a, ...rest) {} : (a: string, ...rest: [boolean, ...Iterable<number>[]]) => void
+ >a : string
+ >rest : [boolean, ...Iterable<number>[]]
+ >'' : ""

testdata/baselines/reference/submodule/compiler/argumentsSpreadRestIterables(target=esnext).types

@@ -24,8 +24,8 @@ declare const itNum: Iterable<number>
 
 ;(function(a, ...rest) {})('', true, ...itNum)
 >(function(a, ...rest) {})('', true, ...itNum) : void
->(function(a, ...rest) {}) : (a: string, rest_0: boolean, ...rest: number[]) => void
->function(a, ...rest) {} : (a: string, rest_0: boolean, ...rest: number[]) => void
+>(function(a, ...rest) {}) : (a: string, ...rest: [boolean, ...number[]]) => void
+>function(a, ...rest) {} : (a: string, ...rest: [boolean, ...number[]]) => void
 >a : string
 >rest : [boolean, ...number[]]
 >'' : ""

testdata/baselines/reference/submodule/compiler/argumentsSpreadRestIterables(target=esnext).types.diff

@@ -0,0 +1,13 @@
+--- old.argumentsSpreadRestIterables(target=esnext).types
++++ new.argumentsSpreadRestIterables(target=esnext).types
+@@= skipped -23, +23 lines =@@
+
+ ;(function(a, ...rest) {})('', true, ...itNum)
+ >(function(a, ...rest) {})('', true, ...itNum) : void
+->(function(a, ...rest) {}) : (a: string, rest_0: boolean, ...rest: number[]) => void
+->function(a, ...rest) {} : (a: string, rest_0: boolean, ...rest: number[]) => void
++>(function(a, ...rest) {}) : (a: string, ...rest: [boolean, ...number[]]) => void
++>function(a, ...rest) {} : (a: string, ...rest: [boolean, ...number[]]) => void
+ >a : string
+ >rest : [boolean, ...number[]]
+ >'' : ""

testdata/baselines/reference/submodule/compiler/bindingPatternCannotBeOnlyInferenceSource.types

@@ -76,19 +76,19 @@ declare function useReduxDispatch1<T extends IDestructuring<TFuncs1>>(destructur
 >destructuring : Destructuring<{ funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }, T>
 
 const {} = useReduxDispatch1(
->useReduxDispatch1(    (d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    })) : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
+>useReduxDispatch1(    (d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    })) : { funcA: (...p: [a: boolean]) => void; funcB: (...p: [b: string, bb: string]) => void; funcC: (...p: [c: number, cc: number, ccc: boolean]) => void; }
 >useReduxDispatch1 : <T extends IDestructuring<{ funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }>>(destructuring: Destructuring<{ funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }, T>) => T
 
     (d, f) => ({
->(d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : (d: Dispatch<any>, f: { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }) => { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
+>(d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : (d: Dispatch<any>, f: { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }) => { funcA: (...p: [a: boolean]) => void; funcB: (...p: [b: string, bb: string]) => void; funcC: (...p: [c: number, cc: number, ccc: boolean]) => void; }
 >d : Dispatch<any>
 >f : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
->({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
->{        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    } : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
+>({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : { funcA: (...p: [a: boolean]) => void; funcB: (...p: [b: string, bb: string]) => void; funcC: (...p: [c: number, cc: number, ccc: boolean]) => void; }
+>{        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    } : { funcA: (...p: [a: boolean]) => void; funcB: (...p: [b: string, bb: string]) => void; funcC: (...p: [c: number, cc: number, ccc: boolean]) => void; }
 
         funcA: (...p) => d(f.funcA(...p)), // p should be inferrable
->funcA : (a: boolean) => void
->(...p) => d(f.funcA(...p)) : (a: boolean) => void
+>funcA : (...p: [a: boolean]) => void
+>(...p) => d(f.funcA(...p)) : (...p: [a: boolean]) => void
 >p : [a: boolean]
 >d(f.funcA(...p)) : void
 >d : Dispatch<any>
@@ -100,8 +100,8 @@ const {} = useReduxDispatch1(
 >p : [a: boolean]
 
         funcB: (...p) => d(f.funcB(...p)),
->funcB : (b: string, bb: string) => void
->(...p) => d(f.funcB(...p)) : (b: string, bb: string) => void
+>funcB : (...p: [b: string, bb: string]) => void
+>(...p) => d(f.funcB(...p)) : (...p: [b: string, bb: string]) => void
 >p : [b: string, bb: string]
 >d(f.funcB(...p)) : void
 >d : Dispatch<any>
@@ -113,8 +113,8 @@ const {} = useReduxDispatch1(
 >p : [b: string, bb: string]
 
         funcC: (...p) => d(f.funcC(...p)),
->funcC : (c: number, cc: number, ccc: boolean) => void
->(...p) => d(f.funcC(...p)) : (c: number, cc: number, ccc: boolean) => void
+>funcC : (...p: [c: number, cc: number, ccc: boolean]) => void
+>(...p) => d(f.funcC(...p)) : (...p: [c: number, cc: number, ccc: boolean]) => void
 >p : [c: number, cc: number, ccc: boolean]
 >d(f.funcC(...p)) : void
 >d : Dispatch<any>

testdata/baselines/reference/submodule/compiler/bindingPatternCannotBeOnlyInferenceSource.types.diff

@@ -9,9 +9,48 @@
  >destructuring : Destructuring<{ funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }, T>
 
  const {} = useReduxDispatch1(
- >useReduxDispatch1(    (d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    })) : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
+->useReduxDispatch1(    (d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    })) : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
 ->useReduxDispatch1 : <T extends IDestructuring<TFuncs1>>(destructuring: Destructuring<TFuncs1, T>) => T
++>useReduxDispatch1(    (d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    })) : { funcA: (...p: [a: boolean]) => void; funcB: (...p: [b: string, bb: string]) => void; funcC: (...p: [c: number, cc: number, ccc: boolean]) => void; }
 +>useReduxDispatch1 : <T extends IDestructuring<{ funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }>>(destructuring: Destructuring<{ funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }, T>) => T
 
      (d, f) => ({
- >(d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : (d: Dispatch<any>, f: { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }) => { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
+->(d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : (d: Dispatch<any>, f: { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }) => { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
++>(d, f) => ({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : (d: Dispatch<any>, f: { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }) => { funcA: (...p: [a: boolean]) => void; funcB: (...p: [b: string, bb: string]) => void; funcC: (...p: [c: number, cc: number, ccc: boolean]) => void; }
+ >d : Dispatch<any>
+ >f : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
+->({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
+->{        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    } : { funcA: (a: boolean) => void; funcB: (b: string, bb: string) => void; funcC: (c: number, cc: number, ccc: boolean) => void; }
++>({        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    }) : { funcA: (...p: [a: boolean]) => void; funcB: (...p: [b: string, bb: string]) => void; funcC: (...p: [c: number, cc: number, ccc: boolean]) => void; }
++>{        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable        funcB: (...p) => d(f.funcB(...p)),        funcC: (...p) => d(f.funcC(...p)),    } : { funcA: (...p: [a: boolean]) => void; funcB: (...p: [b: string, bb: string]) => void; funcC: (...p: [c: number, cc: number, ccc: boolean]) => void; }
+
+         funcA: (...p) => d(f.funcA(...p)), // p should be inferrable
+->funcA : (a: boolean) => void
+->(...p) => d(f.funcA(...p)) : (a: boolean) => void
++>funcA : (...p: [a: boolean]) => void
++>(...p) => d(f.funcA(...p)) : (...p: [a: boolean]) => void
+ >p : [a: boolean]
+ >d(f.funcA(...p)) : void
+ >d : Dispatch<any>
+@@= skipped -28, +28 lines =@@
+ >p : [a: boolean]
+
+         funcB: (...p) => d(f.funcB(...p)),
+->funcB : (b: string, bb: string) => void
+->(...p) => d(f.funcB(...p)) : (b: string, bb: string) => void
++>funcB : (...p: [b: string, bb: string]) => void
++>(...p) => d(f.funcB(...p)) : (...p: [b: string, bb: string]) => void
+ >p : [b: string, bb: string]
+ >d(f.funcB(...p)) : void
+ >d : Dispatch<any>
+@@= skipped -13, +13 lines =@@
+ >p : [b: string, bb: string]
+
+         funcC: (...p) => d(f.funcC(...p)),
+->funcC : (c: number, cc: number, ccc: boolean) => void
+->(...p) => d(f.funcC(...p)) : (c: number, cc: number, ccc: boolean) => void
++>funcC : (...p: [c: number, cc: number, ccc: boolean]) => void
++>(...p) => d(f.funcC(...p)) : (...p: [c: number, cc: number, ccc: boolean]) => void
+ >p : [c: number, cc: number, ccc: boolean]
+ >d(f.funcC(...p)) : void
+ >d : Dispatch<any>

testdata/baselines/reference/submodule/compiler/contextuallyTypedParametersWithInitializers1.types

@@ -155,7 +155,7 @@ const f7: () => any = (x?) => 0;  // Implicit any error
 
 const f8: () => any = (...x) => 0;  // []
 >f8 : () => any
->(...x) => 0 : () => number
+>(...x) => 0 : (...x: []) => number
 >x : []
 >0 : 0
 
@@ -240,9 +240,9 @@ g6((x?) => 0);     // Implicit any error
 >0 : 0
 
 g6((...x) => 0);   // []
->g6((...x) => 0) : () => number
+>g6((...x) => 0) : (...x: []) => number
 >g6 : <T extends () => any>(x: T) => T
->(...x) => 0 : () => number
+>(...x) => 0 : (...x: []) => number
 >x : []
 >0 : 0
 

testdata/baselines/reference/submodule/compiler/contextuallyTypedParametersWithInitializers1.types.diff

@@ -40,4 +40,24 @@
 +>id5 : <T extends (x?: number | undefined) => any>(input: T) => T
  >function (foo = 42) { return foo } : (foo?: number | undefined) => number
  >foo : number | undefined
- >42 : 42
+ >42 : 42
+@@= skipped -57, +57 lines =@@
+
+ const f8: () => any = (...x) => 0;  // []
+ >f8 : () => any
+->(...x) => 0 : () => number
++>(...x) => 0 : (...x: []) => number
+ >x : []
+ >0 : 0
+
+@@= skipped -85, +85 lines =@@
+ >0 : 0
+
+ g6((...x) => 0);   // []
+->g6((...x) => 0) : () => number
++>g6((...x) => 0) : (...x: []) => number
+ >g6 : <T extends () => any>(x: T) => T
+->(...x) => 0 : () => number
++>(...x) => 0 : (...x: []) => number
+ >x : []
+ >0 : 0

testdata/baselines/reference/submodule/compiler/correlatedUnions.types

@@ -491,7 +491,7 @@ function ff1() {
 >Keys : keyof { sum: [a: number, b: number]; concat: [a: string, b: string, c: string]; }
 
     const funs: { [P in Keys]: (...args: ArgMap[P]) => void } = {
->funs : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }
+>funs : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }
 >args : { sum: [a: number, b: number]; concat: [a: string, b: string, c: string]; }[P]
 >{        sum: (a, b) => a + b,        concat: (a, b, c) => a + b + c    } : { sum: (a: number, b: number) => number; concat: (a: string, b: string, c: string) => string; }
 
@@ -522,14 +522,14 @@ function ff1() {
 >args : { sum: [a: number, b: number]; concat: [a: string, b: string, c: string]; }[K]
 
         const fn = funs[funKey];
->fn : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }[K]
->funs[funKey] : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }[K]
->funs : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }
+>fn : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }[K]
+>funs[funKey] : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }[K]
+>funs : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }
 >funKey : K
 
         fn(...args);
 >fn(...args) : void
->fn : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }[K]
+>fn : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }[K]
 >...args : string | number
 >args : { sum: [a: number, b: number]; concat: [a: string, b: string, c: string]; }[K]
     }

testdata/baselines/reference/submodule/compiler/correlatedUnions.types.diff

@@ -95,7 +95,35 @@
 
  processEvents([
  >processEvents([    { name: "click", callback: ev => console.log(ev) },    { name: "scroll", callback: ev => console.log(ev) },]) : void
-@@= skipped -180, +180 lines =@@
+@@= skipped -55, +55 lines =@@
+ >Keys : keyof { sum: [a: number, b: number]; concat: [a: string, b: string, c: string]; }
+
+     const funs: { [P in Keys]: (...args: ArgMap[P]) => void } = {
+->funs : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }
++>funs : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }
+ >args : { sum: [a: number, b: number]; concat: [a: string, b: string, c: string]; }[P]
+ >{        sum: (a, b) => a + b,        concat: (a, b, c) => a + b + c    } : { sum: (a: number, b: number) => number; concat: (a: string, b: string, c: string) => string; }
+
+@@= skipped -31, +31 lines =@@
+ >args : { sum: [a: number, b: number]; concat: [a: string, b: string, c: string]; }[K]
+
+         const fn = funs[funKey];
+->fn : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }[K]
+->funs[funKey] : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }[K]
+->funs : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }
++>fn : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }[K]
++>funs[funKey] : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }[K]
++>funs : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }
+ >funKey : K
+
+         fn(...args);
+ >fn(...args) : void
+->fn : { concat: (a: string, b: string, c: string) => void; sum: (a: number, b: number) => void; }[K]
++>fn : { concat: (...args: [a: string, b: string, c: string]) => void; sum: (...args: [a: number, b: number]) => void; }[K]
+ >...args : string | number
+ >args : { sum: [a: number, b: number]; concat: [a: string, b: string, c: string]; }[K]
+     }
+@@= skipped -94, +94 lines =@@
  }
 
  function f4<K extends keyof ArgMap>(x: Funcs[keyof ArgMap], y: Funcs[K]) {