PR-50377-redo-filterBooleanOverload

src/compiler/checker.ts

@@ -14749,19 +14749,38 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
      * maps primitive types and type parameters are to their apparent types.
      */
     function getSignaturesOfType(type: Type, kind: SignatureKind): readonly Signature[] {
-        const result = getSignaturesOfStructuredType(getReducedApparentType(type), kind);
-        if (kind === SignatureKind.Call && !length(result) && type.flags & TypeFlags.Union) {
+        function carveoutResult(type: Type, kind: SignatureKind): readonly Signature[] | undefined {
+            if (kind === SignatureKind.Call && type.flags & TypeFlags.Union) {
+                // If the union is all different instantiations of a member of the global array type...
+                let memberName: __String;
+                if (everyType(type, t => !!t.symbol?.parent && isArrayOrTupleSymbol(t.symbol.parent) && (!memberName ? (memberName = t.symbol.escapedName, true) : memberName === t.symbol.escapedName))) {
+                    if ((type as UnionType).arrayFallbackSignatures) {
+                        return (type as UnionType).arrayFallbackSignatures!;
+                    }
+                    const arrayArg = mapType(type, t => getMappedType((isReadonlyArraySymbol(t.symbol.parent) ? globalReadonlyArrayType : globalArrayType).typeParameters![0], (t as AnonymousType).mapper!));
+                    const arrayType = createArrayType(arrayArg, someType(type, t => isReadonlyArraySymbol(t.symbol.parent)));
+                    return (type as UnionType).arrayFallbackSignatures = getSignaturesOfType(getTypeOfPropertyOfType(arrayType, memberName!)!, kind);
+                }
+            }
+            return undefined;
+        }
+        let result = carveoutResult(type, kind);
+        if (result) return result;
+        // The original logical for the non-carveout case is recorded in the block comment below, for the record.
+        // result = getSignaturesOfStructuredType(getReducedApparentType(type), kind);
+        // if (kind === SignatureKind.Call && !length(result) && type.flags & TypeFlags.Union) {
+        //     if ((type as UnionType).arrayFallbackSignatures) {
+        //         return (type as UnionType).arrayFallbackSignatures!;
+        //     }
+        //     return (type as UnionType).arrayFallbackSignatures = result;
+        // }
+        if (kind === SignatureKind.Call && type.flags & TypeFlags.Union) {
             if ((type as UnionType).arrayFallbackSignatures) {
                 return (type as UnionType).arrayFallbackSignatures!;
             }
-            // If the union is all different instantiations of a member of the global array type...
-            let memberName: __String;
-            if (everyType(type, t => !!t.symbol?.parent && isArrayOrTupleSymbol(t.symbol.parent) && (!memberName ? (memberName = t.symbol.escapedName, true) : memberName === t.symbol.escapedName))) {
-                // Transform the type from `(A[] | B[])["member"]` to `(A | B)[]["member"]` (since we pretend array is covariant anyway)
-                const arrayArg = mapType(type, t => getMappedType((isReadonlyArraySymbol(t.symbol.parent) ? globalReadonlyArrayType : globalArrayType).typeParameters![0], (t as AnonymousType).mapper!));
-                const arrayType = createArrayType(arrayArg, someType(type, t => isReadonlyArraySymbol(t.symbol.parent)));
-                return (type as UnionType).arrayFallbackSignatures = getSignaturesOfType(getTypeOfPropertyOfType(arrayType, memberName!)!, kind);
-            }
+        }
+        result = getSignaturesOfStructuredType(getReducedApparentType(type), kind);
+        if (kind === SignatureKind.Call && type.flags & TypeFlags.Union) {
             (type as UnionType).arrayFallbackSignatures = result;
         }
         return result;

src/lib/es5.d.ts

@@ -1257,6 +1257,12 @@ interface ReadonlyArray<T> {
      * @param thisArg An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.
      */
     filter<S extends T>(predicate: (value: T, index: number, array: readonly T[]) => value is S, thisArg?: any): S[];
+    /**
+     * Returns the non-Falsy elements of an array
+     * @param predicate Must be exactly "Boolean"
+     * @param thisArg An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.
+     */
+    filter(predicate: BooleanConstructor, thisArg?: any): (T extends false | 0 | "" | null | undefined | 0n ? never : T)[];
     /**
      * Returns the elements of an array that meet the condition specified in a callback function.
      * @param predicate A function that accepts up to three arguments. The filter method calls the predicate function one time for each element in the array.
@@ -1448,6 +1454,12 @@ interface Array<T> {
      * @param thisArg An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.
      */
     filter<S extends T>(predicate: (value: T, index: number, array: T[]) => value is S, thisArg?: any): S[];
+    /**
+     * Returns the non-Falsy elements of an array
+     * @param predicate Must be exactly "Boolean"
+     * @param thisArg An object to which the this keyword can refer in the predicate function. If thisArg is omitted, undefined is used as the this value.
+     */
+    filter(predicate: BooleanConstructor, thisArg?: any): (T extends false | 0 | "" | null | undefined | 0n ? never : T)[];
     /**
      * Returns the elements of an array that meet the condition specified in a callback function.
      * @param predicate A function that accepts up to three arguments. The filter method calls the predicate function one time for each element in the array.

tests/baselines/reference/arrayFilter.symbols

@@ -16,9 +16,9 @@ var foo = [
 ]
 
 foo.filter(x => x.name); //should accepted all possible types not only boolean! 
->foo.filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>foo.filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
 >foo : Symbol(foo, Decl(arrayFilter.ts, 0, 3))
->filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
 >x : Symbol(x, Decl(arrayFilter.ts, 6, 11))
 >x.name : Symbol(name, Decl(arrayFilter.ts, 1, 5))
 >x : Symbol(x, Decl(arrayFilter.ts, 6, 11))

tests/baselines/reference/arrayFilter.types

@@ -23,9 +23,9 @@ var foo = [
 
 foo.filter(x => x.name); //should accepted all possible types not only boolean! 
 >foo.filter(x => x.name) : { name: string; }[]
->foo.filter : { <S extends { name: string; }>(predicate: (value: { name: string; }, index: number, array: { name: string; }[]) => value is S, thisArg?: any): S[]; (predicate: (value: { name: string; }, index: number, array: { name: string; }[]) => unknown, thisArg?: any): { name: string; }[]; }
+>foo.filter : { <S extends { name: string; }>(predicate: (value: { name: string; }, index: number, array: { name: string; }[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): { name: string; }[]; (predicate: (value: { name: string; }, index: number, array: { name: string; }[]) => unknown, thisArg?: any): { name: string; }[]; }
 >foo : { name: string; }[]
->filter : { <S extends { name: string; }>(predicate: (value: { name: string; }, index: number, array: { name: string; }[]) => value is S, thisArg?: any): S[]; (predicate: (value: { name: string; }, index: number, array: { name: string; }[]) => unknown, thisArg?: any): { name: string; }[]; }
+>filter : { <S extends { name: string; }>(predicate: (value: { name: string; }, index: number, array: { name: string; }[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): { name: string; }[]; (predicate: (value: { name: string; }, index: number, array: { name: string; }[]) => unknown, thisArg?: any): { name: string; }[]; }
 >x => x.name : (x: { name: string; }) => string
 >x : { name: string; }
 >x.name : string

tests/baselines/reference/arrayFilterBooleanOverload#56013WithoutExternalOverload.js

@@ -0,0 +1,32 @@
+//// [tests/cases/compiler/arrayFilterBooleanOverload#56013WithoutExternalOverload.ts] ////
+
+//// [arrayFilterBooleanOverload#56013WithoutExternalOverload.ts]
+type NonFalsy<T> = T extends false | 0 | "" | null | undefined | 0n
+    ? never
+    : T;
+
+const id = <T,>() => (t: T) => !!t;
+
+['foo', 'bar'].filter(id()); // // expect id() = (t: string) => boolean
+
+['foo', 'bar', 1].filter(id()); // // expect id() = (t: string | number) => boolean
+
+declare const maybe: boolean;
+(maybe ? ['foo', 'bar'] : [1] ).filter(id()); // expect id() = (t: string | number) => boolean
+
+['foo', 'bar', undefined].filter(id()); // expect id() = (t: string | undefined) => boolean
+
+
+//// [arrayFilterBooleanOverload#56013WithoutExternalOverload.js]
+"use strict";
+const id = () => (t) => !!t;
+['foo', 'bar'].filter(id()); // // expect id() = (t: string) => boolean
+['foo', 'bar', 1].filter(id()); // // expect id() = (t: string | number) => boolean
+(maybe ? ['foo', 'bar'] : [1]).filter(id()); // expect id() = (t: string | number) => boolean
+['foo', 'bar', undefined].filter(id()); // expect id() = (t: string | undefined) => boolean
+
+
+//// [arrayFilterBooleanOverload#56013WithoutExternalOverload.d.ts]
+type NonFalsy<T> = T extends false | 0 | "" | null | undefined | 0n ? never : T;
+declare const id: <T>() => (t: T) => boolean;
+declare const maybe: boolean;

tests/baselines/reference/arrayFilterBooleanOverload#56013WithoutExternalOverload.symbols

@@ -0,0 +1,44 @@
+//// [tests/cases/compiler/arrayFilterBooleanOverload#56013WithoutExternalOverload.ts] ////
+
+=== arrayFilterBooleanOverload#56013WithoutExternalOverload.ts ===
+type NonFalsy<T> = T extends false | 0 | "" | null | undefined | 0n
+>NonFalsy : Symbol(NonFalsy, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 0, 0))
+>T : Symbol(T, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 0, 14))
+>T : Symbol(T, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 0, 14))
+
+    ? never
+    : T;
+>T : Symbol(T, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 0, 14))
+
+const id = <T,>() => (t: T) => !!t;
+>id : Symbol(id, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 5))
+>T : Symbol(T, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 12))
+>t : Symbol(t, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 22))
+>T : Symbol(T, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 12))
+>t : Symbol(t, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 22))
+
+['foo', 'bar'].filter(id()); // // expect id() = (t: string) => boolean
+>['foo', 'bar'].filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>id : Symbol(id, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 5))
+
+['foo', 'bar', 1].filter(id()); // // expect id() = (t: string | number) => boolean
+>['foo', 'bar', 1].filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>id : Symbol(id, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 5))
+
+declare const maybe: boolean;
+>maybe : Symbol(maybe, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 10, 13))
+
+(maybe ? ['foo', 'bar'] : [1] ).filter(id()); // expect id() = (t: string | number) => boolean
+>(maybe ? ['foo', 'bar'] : [1] ).filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --) ... and 1 more)
+>maybe : Symbol(maybe, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 10, 13))
+>filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --) ... and 1 more)
+>id : Symbol(id, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 5))
+
+['foo', 'bar', undefined].filter(id()); // expect id() = (t: string | undefined) => boolean
+>['foo', 'bar', undefined].filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>undefined : Symbol(undefined)
+>filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
+>id : Symbol(id, Decl(arrayFilterBooleanOverload#56013WithoutExternalOverload.ts, 4, 5))
+

tests/baselines/reference/arrayFilterBooleanOverload#56013WithoutExternalOverload.types

@@ -0,0 +1,69 @@
+//// [tests/cases/compiler/arrayFilterBooleanOverload#56013WithoutExternalOverload.ts] ////
+
+=== arrayFilterBooleanOverload#56013WithoutExternalOverload.ts ===
+type NonFalsy<T> = T extends false | 0 | "" | null | undefined | 0n
+>NonFalsy : NonFalsy<T>
+>false : false
+
+    ? never
+    : T;
+
+const id = <T,>() => (t: T) => !!t;
+>id : <T>() => (t: T) => boolean
+><T,>() => (t: T) => !!t : <T>() => (t: T) => boolean
+>(t: T) => !!t : (t: T) => boolean
+>t : T
+>!!t : boolean
+>!t : boolean
+>t : T
+
+['foo', 'bar'].filter(id()); // // expect id() = (t: string) => boolean
+>['foo', 'bar'].filter(id()) : string[]
+>['foo', 'bar'].filter : { <S extends string>(predicate: (value: string, index: number, array: string[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): string[]; (predicate: (value: string, index: number, array: string[]) => unknown, thisArg?: any): string[]; }
+>['foo', 'bar'] : string[]
+>'foo' : "foo"
+>'bar' : "bar"
+>filter : { <S extends string>(predicate: (value: string, index: number, array: string[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): string[]; (predicate: (value: string, index: number, array: string[]) => unknown, thisArg?: any): string[]; }
+>id() : (t: string) => boolean
+>id : <T>() => (t: T) => boolean
+
+['foo', 'bar', 1].filter(id()); // // expect id() = (t: string | number) => boolean
+>['foo', 'bar', 1].filter(id()) : (string | number)[]
+>['foo', 'bar', 1].filter : { <S extends string | number>(predicate: (value: string | number, index: number, array: (string | number)[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): (string | number)[]; (predicate: (value: string | number, index: number, array: (string | number)[]) => unknown, thisArg?: any): (string | number)[]; }
+>['foo', 'bar', 1] : (string | number)[]
+>'foo' : "foo"
+>'bar' : "bar"
+>1 : 1
+>filter : { <S extends string | number>(predicate: (value: string | number, index: number, array: (string | number)[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): (string | number)[]; (predicate: (value: string | number, index: number, array: (string | number)[]) => unknown, thisArg?: any): (string | number)[]; }
+>id() : (t: string | number) => boolean
+>id : <T>() => (t: T) => boolean
+
+declare const maybe: boolean;
+>maybe : boolean
+
+(maybe ? ['foo', 'bar'] : [1] ).filter(id()); // expect id() = (t: string | number) => boolean
+>(maybe ? ['foo', 'bar'] : [1] ).filter(id()) : (string | number)[]
+>(maybe ? ['foo', 'bar'] : [1] ).filter : { <S extends string>(predicate: (value: string, index: number, array: string[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): string[]; (predicate: (value: string, index: number, array: string[]) => unknown, thisArg?: any): string[]; } | { <S extends number>(predicate: (value: number, index: number, array: number[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): number[]; (predicate: (value: number, index: number, array: number[]) => unknown, thisArg?: any): number[]; }
+>(maybe ? ['foo', 'bar'] : [1] ) : string[] | number[]
+>maybe ? ['foo', 'bar'] : [1] : string[] | number[]
+>maybe : boolean
+>['foo', 'bar'] : string[]
+>'foo' : "foo"
+>'bar' : "bar"
+>[1] : number[]
+>1 : 1
+>filter : { <S extends string>(predicate: (value: string, index: number, array: string[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): string[]; (predicate: (value: string, index: number, array: string[]) => unknown, thisArg?: any): string[]; } | { <S extends number>(predicate: (value: number, index: number, array: number[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): number[]; (predicate: (value: number, index: number, array: number[]) => unknown, thisArg?: any): number[]; }
+>id() : (t: string | number) => boolean
+>id : <T>() => (t: T) => boolean
+
+['foo', 'bar', undefined].filter(id()); // expect id() = (t: string | undefined) => boolean
+>['foo', 'bar', undefined].filter(id()) : (string | undefined)[]
+>['foo', 'bar', undefined].filter : { <S extends string | undefined>(predicate: (value: string | undefined, index: number, array: (string | undefined)[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): string[]; (predicate: (value: string | undefined, index: number, array: (string | undefined)[]) => unknown, thisArg?: any): (string | undefined)[]; }
+>['foo', 'bar', undefined] : (string | undefined)[]
+>'foo' : "foo"
+>'bar' : "bar"
+>undefined : undefined
+>filter : { <S extends string | undefined>(predicate: (value: string | undefined, index: number, array: (string | undefined)[]) => value is S, thisArg?: any): S[]; (predicate: BooleanConstructor, thisArg?: any): string[]; (predicate: (value: string | undefined, index: number, array: (string | undefined)[]) => unknown, thisArg?: any): (string | undefined)[]; }
+>id() : (t: string | undefined) => boolean
+>id : <T>() => (t: T) => boolean
+

tests/baselines/reference/arrayFilterBooleanOverload.js

@@ -0,0 +1,32 @@
+//// [tests/cases/compiler/arrayFilterBooleanOverload.ts] ////
+
+//// [arrayFilterBooleanOverload.ts]
+const nullableValues = ['a', 'b', null]; // expect (string | null)[]
+
+const values1 = nullableValues.filter(Boolean); // expect string[]
+
+// @ts-expect-error
+const values2 = nullableValues.filter(new Boolean);
+
+const arr = [0, 1, "", "foo", null] as const;
+
+const arr2 = arr.filter(Boolean); // expect ("foo" | 1)[]
+
+
+
+//// [arrayFilterBooleanOverload.js]
+"use strict";
+const nullableValues = ['a', 'b', null]; // expect (string | null)[]
+const values1 = nullableValues.filter(Boolean); // expect string[]
+// @ts-expect-error
+const values2 = nullableValues.filter(new Boolean);
+const arr = [0, 1, "", "foo", null];
+const arr2 = arr.filter(Boolean); // expect ("foo" | 1)[]
+
+
+//// [arrayFilterBooleanOverload.d.ts]
+declare const nullableValues: (string | null)[];
+declare const values1: string[];
+declare const values2: (string | null)[];
+declare const arr: readonly [0, 1, "", "foo", null];
+declare const arr2: (1 | "foo")[];