Merge pull request #24627 from Microsoft/typeofFunction

Fix typeof x === "function" type guards
2026-02-05 16:38:05 -06:00 · 2018-06-02 18:46:52 -07:00 · 2018-06-02 18:46:52 -07:00 · 667de4bbb9
commit 667de4bbb9
parent 64c366562e 8b38d357e1
5 changed files with 566 additions and 1 deletions
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@ -14112,11 +14112,14 @@ namespace ts {
                if (operator === SyntaxKind.ExclamationEqualsToken || operator === SyntaxKind.ExclamationEqualsEqualsToken) {
                    assumeTrue = !assumeTrue;
                }
+                if (type.flags & TypeFlags.Any && literal.text === "function") {
+                    return type;
+                }
                if (assumeTrue && !(type.flags & TypeFlags.Union)) {
                    // We narrow a non-union type to an exact primitive type if the non-union type
                    // is a supertype of that primitive type. For example, type 'any' can be narrowed
                    // to one of the primitive types.
-                    const targetType = typeofTypesByName.get(literal.text);
+                    const targetType = literal.text === "function" ? globalFunctionType : typeofTypesByName.get(literal.text);
                    if (targetType) {
                        if (isTypeSubtypeOf(targetType, type)) {
                            return targetType;
--- a/tests/baselines/reference/typeGuardOfFormTypeOfFunction.js
+++ b/tests/baselines/reference/typeGuardOfFormTypeOfFunction.js
@ -0,0 +1,139 @@
+//// [typeGuardOfFormTypeOfFunction.ts]
+function f1(x: any) {
+    if (typeof x === "function") {
+        x;  // any
+    }
+}
+
+function f2(x: unknown) {
+    if (typeof x === "function") {
+        x;  // Function
+    }
+}
+
+function f3(x: {}) {
+    if (typeof x === "function") {
+        x;  // Function
+    }
+}
+
+function f4<T>(x: T) {
+    if (typeof x === "function") {
+        x;  // T & Function
+    }
+}
+
+function f5(x: { s: string }) {
+    if (typeof x === "function") {
+        x;  // never
+    }
+}
+
+function f6(x: () => string) {
+    if (typeof x === "function") {
+        x;  // () => string
+    }
+}
+
+function f10(x: string | (() => string)) {
+    if (typeof x === "function") {
+        x;  // () => string
+    }
+    else {
+        x;  // string
+    }
+}
+
+function f11(x: { s: string } | (() => string)) {
+    if (typeof x === "function") {
+        x;  // () => string
+    }
+    else {
+        x;  // { s: string }
+    }
+}
+
+function f12(x: { s: string } | { n: number }) {
+    if (typeof x === "function") {
+        x;  // never
+    }
+    else {
+        x;  // { s: string } | { n: number }
+    }
+}
+
+// Repro from #18238
+
+function f100<T, K extends keyof T>(obj: T, keys: K[]) : void {
+    for (const k of keys) {
+        const item = obj[k];
+        if (typeof item == 'function')
+            item.call(obj);
+    }
+}
+
+
+//// [typeGuardOfFormTypeOfFunction.js]
+function f1(x) {
+    if (typeof x === "function") {
+        x; // any
+    }
+}
+function f2(x) {
+    if (typeof x === "function") {
+        x; // Function
+    }
+}
+function f3(x) {
+    if (typeof x === "function") {
+        x; // Function
+    }
+}
+function f4(x) {
+    if (typeof x === "function") {
+        x; // T & Function
+    }
+}
+function f5(x) {
+    if (typeof x === "function") {
+        x; // never
+    }
+}
+function f6(x) {
+    if (typeof x === "function") {
+        x; // () => string
+    }
+}
+function f10(x) {
+    if (typeof x === "function") {
+        x; // () => string
+    }
+    else {
+        x; // string
+    }
+}
+function f11(x) {
+    if (typeof x === "function") {
+        x; // () => string
+    }
+    else {
+        x; // { s: string }
+    }
+}
+function f12(x) {
+    if (typeof x === "function") {
+        x; // never
+    }
+    else {
+        x; // { s: string } | { n: number }
+    }
+}
+// Repro from #18238
+function f100(obj, keys) {
+    for (var _i = 0, keys_1 = keys; _i < keys_1.length; _i++) {
+        var k = keys_1[_i];
+        var item = obj[k];
+        if (typeof item == 'function')
+            item.call(obj);
+    }
+}
--- a/tests/baselines/reference/typeGuardOfFormTypeOfFunction.symbols
+++ b/tests/baselines/reference/typeGuardOfFormTypeOfFunction.symbols
@ -0,0 +1,159 @@
+=== tests/cases/conformance/expressions/typeGuards/typeGuardOfFormTypeOfFunction.ts ===
+function f1(x: any) {
+>f1 : Symbol(f1, Decl(typeGuardOfFormTypeOfFunction.ts, 0, 0))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 0, 12))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 0, 12))
+
+        x;  // any
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 0, 12))
+    }
+}
+
+function f2(x: unknown) {
+>f2 : Symbol(f2, Decl(typeGuardOfFormTypeOfFunction.ts, 4, 1))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 6, 12))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 6, 12))
+
+        x;  // Function
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 6, 12))
+    }
+}
+
+function f3(x: {}) {
+>f3 : Symbol(f3, Decl(typeGuardOfFormTypeOfFunction.ts, 10, 1))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 12, 12))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 12, 12))
+
+        x;  // Function
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 12, 12))
+    }
+}
+
+function f4<T>(x: T) {
+>f4 : Symbol(f4, Decl(typeGuardOfFormTypeOfFunction.ts, 16, 1))
+>T : Symbol(T, Decl(typeGuardOfFormTypeOfFunction.ts, 18, 12))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 18, 15))
+>T : Symbol(T, Decl(typeGuardOfFormTypeOfFunction.ts, 18, 12))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 18, 15))
+
+        x;  // T & Function
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 18, 15))
+    }
+}
+
+function f5(x: { s: string }) {
+>f5 : Symbol(f5, Decl(typeGuardOfFormTypeOfFunction.ts, 22, 1))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 24, 12))
+>s : Symbol(s, Decl(typeGuardOfFormTypeOfFunction.ts, 24, 16))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 24, 12))
+
+        x;  // never
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 24, 12))
+    }
+}
+
+function f6(x: () => string) {
+>f6 : Symbol(f6, Decl(typeGuardOfFormTypeOfFunction.ts, 28, 1))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 30, 12))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 30, 12))
+
+        x;  // () => string
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 30, 12))
+    }
+}
+
+function f10(x: string | (() => string)) {
+>f10 : Symbol(f10, Decl(typeGuardOfFormTypeOfFunction.ts, 34, 1))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 36, 13))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 36, 13))
+
+        x;  // () => string
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 36, 13))
+    }
+    else {
+        x;  // string
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 36, 13))
+    }
+}
+
+function f11(x: { s: string } | (() => string)) {
+>f11 : Symbol(f11, Decl(typeGuardOfFormTypeOfFunction.ts, 43, 1))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 45, 13))
+>s : Symbol(s, Decl(typeGuardOfFormTypeOfFunction.ts, 45, 17))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 45, 13))
+
+        x;  // () => string
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 45, 13))
+    }
+    else {
+        x;  // { s: string }
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 45, 13))
+    }
+}
+
+function f12(x: { s: string } | { n: number }) {
+>f12 : Symbol(f12, Decl(typeGuardOfFormTypeOfFunction.ts, 52, 1))
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 54, 13))
+>s : Symbol(s, Decl(typeGuardOfFormTypeOfFunction.ts, 54, 17))
+>n : Symbol(n, Decl(typeGuardOfFormTypeOfFunction.ts, 54, 33))
+
+    if (typeof x === "function") {
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 54, 13))
+
+        x;  // never
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 54, 13))
+    }
+    else {
+        x;  // { s: string } | { n: number }
+>x : Symbol(x, Decl(typeGuardOfFormTypeOfFunction.ts, 54, 13))
+    }
+}
+
+// Repro from #18238
+
+function f100<T, K extends keyof T>(obj: T, keys: K[]) : void {
+>f100 : Symbol(f100, Decl(typeGuardOfFormTypeOfFunction.ts, 61, 1))
+>T : Symbol(T, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 14))
+>K : Symbol(K, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 16))
+>T : Symbol(T, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 14))
+>obj : Symbol(obj, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 36))
+>T : Symbol(T, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 14))
+>keys : Symbol(keys, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 43))
+>K : Symbol(K, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 16))
+
+    for (const k of keys) {
+>k : Symbol(k, Decl(typeGuardOfFormTypeOfFunction.ts, 66, 14))
+>keys : Symbol(keys, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 43))
+
+        const item = obj[k];
+>item : Symbol(item, Decl(typeGuardOfFormTypeOfFunction.ts, 67, 13))
+>obj : Symbol(obj, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 36))
+>k : Symbol(k, Decl(typeGuardOfFormTypeOfFunction.ts, 66, 14))
+
+        if (typeof item == 'function')
+>item : Symbol(item, Decl(typeGuardOfFormTypeOfFunction.ts, 67, 13))
+
+            item.call(obj);
+>item.call : Symbol(Function.call, Decl(lib.d.ts, --, --))
+>item : Symbol(item, Decl(typeGuardOfFormTypeOfFunction.ts, 67, 13))
+>call : Symbol(Function.call, Decl(lib.d.ts, --, --))
+>obj : Symbol(obj, Decl(typeGuardOfFormTypeOfFunction.ts, 65, 36))
+    }
+}
+
--- a/tests/baselines/reference/typeGuardOfFormTypeOfFunction.types
+++ b/tests/baselines/reference/typeGuardOfFormTypeOfFunction.types
@ -0,0 +1,191 @@
+=== tests/cases/conformance/expressions/typeGuards/typeGuardOfFormTypeOfFunction.ts ===
+function f1(x: any) {
+>f1 : (x: any) => void
+>x : any
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : any
+>"function" : "function"
+
+        x;  // any
+>x : any
+    }
+}
+
+function f2(x: unknown) {
+>f2 : (x: unknown) => void
+>x : unknown
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : unknown
+>"function" : "function"
+
+        x;  // Function
+>x : Function
+    }
+}
+
+function f3(x: {}) {
+>f3 : (x: {}) => void
+>x : {}
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : {}
+>"function" : "function"
+
+        x;  // Function
+>x : Function
+    }
+}
+
+function f4<T>(x: T) {
+>f4 : <T>(x: T) => void
+>T : T
+>x : T
+>T : T
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : T
+>"function" : "function"
+
+        x;  // T & Function
+>x : T & Function
+    }
+}
+
+function f5(x: { s: string }) {
+>f5 : (x: { s: string; }) => void
+>x : { s: string; }
+>s : string
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : { s: string; }
+>"function" : "function"
+
+        x;  // never
+>x : never
+    }
+}
+
+function f6(x: () => string) {
+>f6 : (x: () => string) => void
+>x : () => string
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : () => string
+>"function" : "function"
+
+        x;  // () => string
+>x : () => string
+    }
+}
+
+function f10(x: string | (() => string)) {
+>f10 : (x: string | (() => string)) => void
+>x : string | (() => string)
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : string | (() => string)
+>"function" : "function"
+
+        x;  // () => string
+>x : () => string
+    }
+    else {
+        x;  // string
+>x : string
+    }
+}
+
+function f11(x: { s: string } | (() => string)) {
+>f11 : (x: { s: string; } | (() => string)) => void
+>x : { s: string; } | (() => string)
+>s : string
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : { s: string; } | (() => string)
+>"function" : "function"
+
+        x;  // () => string
+>x : () => string
+    }
+    else {
+        x;  // { s: string }
+>x : { s: string; }
+    }
+}
+
+function f12(x: { s: string } | { n: number }) {
+>f12 : (x: { s: string; } | { n: number; }) => void
+>x : { s: string; } | { n: number; }
+>s : string
+>n : number
+
+    if (typeof x === "function") {
+>typeof x === "function" : boolean
+>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>x : { s: string; } | { n: number; }
+>"function" : "function"
+
+        x;  // never
+>x : never
+    }
+    else {
+        x;  // { s: string } | { n: number }
+>x : { s: string; } | { n: number; }
+    }
+}
+
+// Repro from #18238
+
+function f100<T, K extends keyof T>(obj: T, keys: K[]) : void {
+>f100 : <T, K extends keyof T>(obj: T, keys: K[]) => void
+>T : T
+>K : K
+>T : T
+>obj : T
+>T : T
+>keys : K[]
+>K : K
+
+    for (const k of keys) {
+>k : K
+>keys : K[]
+
+        const item = obj[k];
+>item : T[K]
+>obj[k] : T[K]
+>obj : T
+>k : K
+
+        if (typeof item == 'function')
+>typeof item == 'function' : boolean
+>typeof item : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
+>item : T[K]
+>'function' : "function"
+
+            item.call(obj);
+>item.call(obj) : any
+>item.call : (this: Function, thisArg: any, ...argArray: any[]) => any
+>item : T[K] & Function
+>call : (this: Function, thisArg: any, ...argArray: any[]) => any
+>obj : T
+    }
+}
+
--- a/tests/cases/conformance/expressions/typeGuards/typeGuardOfFormTypeOfFunction.ts
+++ b/tests/cases/conformance/expressions/typeGuards/typeGuardOfFormTypeOfFunction.ts
@ -0,0 +1,73 @@
+
+function f1(x: any) {
+    if (typeof x === "function") {
+        x;  // any
+    }
+}
+
+function f2(x: unknown) {
+    if (typeof x === "function") {
+        x;  // Function
+    }
+}
+
+function f3(x: {}) {
+    if (typeof x === "function") {
+        x;  // Function
+    }
+}
+
+function f4<T>(x: T) {
+    if (typeof x === "function") {
+        x;  // T & Function
+    }
+}
+
+function f5(x: { s: string }) {
+    if (typeof x === "function") {
+        x;  // never
+    }
+}
+
+function f6(x: () => string) {
+    if (typeof x === "function") {
+        x;  // () => string
+    }
+}
+
+function f10(x: string | (() => string)) {
+    if (typeof x === "function") {
+        x;  // () => string
+    }
+    else {
+        x;  // string
+    }
+}
+
+function f11(x: { s: string } | (() => string)) {
+    if (typeof x === "function") {
+        x;  // () => string
+    }
+    else {
+        x;  // { s: string }
+    }
+}
+
+function f12(x: { s: string } | { n: number }) {
+    if (typeof x === "function") {
+        x;  // never
+    }
+    else {
+        x;  // { s: string } | { n: number }
+    }
+}
+
+// Repro from #18238
+
+function f100<T, K extends keyof T>(obj: T, keys: K[]) : void {
+    for (const k of keys) {
+        const item = obj[k];
+        if (typeof item == 'function')
+            item.call(obj);
+    }
+}