Properly strip readonly from rest argument types (microsoft#35169)

* Properly strip readonlyness from rest argument types

* Add tests

* Accept new baselines

Author: ahejlsberg

src/compiler/checker.ts

@@ -23682,10 +23682,10 @@ namespace ts {
         }
 
         function getArrayifiedType(type: Type) {
-            if (forEachType(type, t => !(t.flags & (TypeFlags.Any | TypeFlags.Instantiable) || isArrayType(t) || isTupleType(t)))) {
-                return createArrayType(getIndexedAccessType(type, numberType));
-            }
-            return type;
+            return type.flags & TypeFlags.Union ? mapType(type, getArrayifiedType) :
+                type.flags & (TypeFlags.Any | TypeFlags.Instantiable) || isMutableArrayOrTuple(type) ? type :
+                isTupleType(type) ? createTupleType(getTypeArguments(type), type.target.minLength, type.target.hasRestElement, /*readonly*/ false, type.target.associatedNames) :
+                createArrayType(getIndexedAccessType(type, numberType));
         }
 
         function getSpreadArgumentType(args: readonly Expression[], index: number, argCount: number, restType: Type, context: InferenceContext | undefined) {

tests/baselines/reference/genericRestParameters3.errors.txt

@@ -1,36 +1,36 @@
-tests/cases/conformance/types/rest/genericRestParameters3.ts(11,11): error TS2345: Argument of type '[10]' is not assignable to parameter of type '[string] | [number, boolean]'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(17,11): error TS2345: Argument of type '[10]' is not assignable to parameter of type '[string] | [number, boolean]'.
   Type '[10]' is not assignable to type '[string]'.
     Type '10' is not assignable to type 'string'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(12,1): error TS2345: Argument of type '[]' is not assignable to parameter of type '[string] | [number, boolean]'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(18,1): error TS2345: Argument of type '[]' is not assignable to parameter of type '[string] | [number, boolean]'.
   Type '[]' is missing the following properties from type '[number, boolean]': 0, 1
-tests/cases/conformance/types/rest/genericRestParameters3.ts(16,1): error TS2322: Type '(x: string, ...args: [string] | [number, boolean]) => void' is not assignable to type '(...args: [string, string] | [string, number, boolean]) => void'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(17,1): error TS2322: Type '(x: string, y: string) => void' is not assignable to type '(x: string, ...args: [string] | [number, boolean]) => void'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(22,1): error TS2322: Type '(x: string, ...args: [string] | [number, boolean]) => void' is not assignable to type '(...args: [string, string] | [string, number, boolean]) => void'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(23,1): error TS2322: Type '(x: string, y: string) => void' is not assignable to type '(x: string, ...args: [string] | [number, boolean]) => void'.
   Types of parameters 'y' and 'args' are incompatible.
     Type '[string] | [number, boolean]' is not assignable to type '[string]'.
       Type '[number, boolean]' is not assignable to type '[string]'.
         Types of property '0' are incompatible.
           Type 'number' is not assignable to type 'string'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(18,1): error TS2322: Type '(x: string, y: number, z: boolean) => void' is not assignable to type '(x: string, ...args: [string] | [number, boolean]) => void'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(24,1): error TS2322: Type '(x: string, y: number, z: boolean) => void' is not assignable to type '(x: string, ...args: [string] | [number, boolean]) => void'.
   Types of parameters 'y' and 'args' are incompatible.
     Type '[string] | [number, boolean]' is not assignable to type '[number, boolean]'.
       Property '1' is missing in type '[string]' but required in type '[number, boolean]'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(19,1): error TS2322: Type '(...args: [string, string] | [string, number, boolean]) => void' is not assignable to type '(x: string, ...args: [string] | [number, boolean]) => void'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(29,1): error TS2554: Expected 1 arguments, but got 0.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(30,21): error TS2345: Argument of type '100' is not assignable to parameter of type '(...args: CoolArray<any>) => void'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(31,21): error TS2345: Argument of type '<T extends any[]>(cb: (...args: T) => void) => void' is not assignable to parameter of type '(...args: CoolArray<any>) => void'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(25,1): error TS2322: Type '(...args: [string, string] | [string, number, boolean]) => void' is not assignable to type '(x: string, ...args: [string] | [number, boolean]) => void'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(35,1): error TS2554: Expected 1 arguments, but got 0.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(36,21): error TS2345: Argument of type '100' is not assignable to parameter of type '(...args: CoolArray<any>) => void'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(37,21): error TS2345: Argument of type '<T extends any[]>(cb: (...args: T) => void) => void' is not assignable to parameter of type '(...args: CoolArray<any>) => void'.
   Types of parameters 'cb' and 'args' are incompatible.
     Property '0' is missing in type 'CoolArray<any>' but required in type '[(...args: any[]) => void]'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(38,32): error TS2345: Argument of type '[10, 20]' is not assignable to parameter of type 'CoolArray<number>'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(44,32): error TS2345: Argument of type '[10, 20]' is not assignable to parameter of type 'CoolArray<number>'.
   Property 'hello' is missing in type '[10, 20]' but required in type 'CoolArray<number>'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(43,1): error TS2345: Argument of type '[]' is not assignable to parameter of type 'CoolArray<unknown>'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(49,1): error TS2345: Argument of type '[]' is not assignable to parameter of type 'CoolArray<unknown>'.
   Property 'hello' is missing in type '[]' but required in type 'CoolArray<unknown>'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(44,5): error TS2345: Argument of type '[number]' is not assignable to parameter of type 'CoolArray<unknown>'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(50,5): error TS2345: Argument of type '[number]' is not assignable to parameter of type 'CoolArray<unknown>'.
   Property 'hello' is missing in type '[number]' but required in type 'CoolArray<unknown>'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(45,5): error TS2345: Argument of type '[number, number]' is not assignable to parameter of type 'CoolArray<unknown>'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(51,5): error TS2345: Argument of type '[number, number]' is not assignable to parameter of type 'CoolArray<unknown>'.
   Property 'hello' is missing in type '[number, number]' but required in type 'CoolArray<unknown>'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(46,5): error TS2345: Argument of type 'number[]' is not assignable to parameter of type 'CoolArray<number>'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(52,5): error TS2345: Argument of type 'number[]' is not assignable to parameter of type 'CoolArray<number>'.
   Property 'hello' is missing in type 'number[]' but required in type 'CoolArray<number>'.
-tests/cases/conformance/types/rest/genericRestParameters3.ts(53,5): error TS2345: Argument of type '["what"]' is not assignable to parameter of type '[] | [number, string]'.
+tests/cases/conformance/types/rest/genericRestParameters3.ts(59,5): error TS2345: Argument of type '["what"]' is not assignable to parameter of type '[] | [number, string]'.
   Property '1' is missing in type '["what"]' but required in type '[number, string]'.
 
 
@@ -40,11 +40,17 @@ tests/cases/conformance/types/rest/genericRestParameters3.ts(53,5): error TS2345
     declare let f3: (x: string, y: number, z: boolean) => void;
     declare let f4: (...args: [string, string] | [string, number, boolean]) => void;
 
-    declare const tt: [string] | [number, boolean];
+    declare const t1: [string] | [number, boolean];
+    declare const t2: readonly [string] | [number, boolean];
+    declare const t3: [string] | readonly [number, boolean];
+    declare const t4: readonly [string] | readonly [number, boolean];
 
     f1("foo", "abc");
     f1("foo", 10, true);
-    f1("foo", ...tt);
+    f1("foo", ...t1);
+    f1("foo", ...t2);
+    f1("foo", ...t3);
+    f1("foo", ...t4);
     f1("foo", 10);  // Error
               ~~
 !!! error TS2345: Argument of type '[10]' is not assignable to parameter of type '[string] | [number, boolean]'.
@@ -89,7 +95,7 @@ tests/cases/conformance/types/rest/genericRestParameters3.ts(53,5): error TS2345
     foo<CoolArray<any>>();     // Error
     ~~~~~~~~~~~~~~~~~~~~~
 !!! error TS2554: Expected 1 arguments, but got 0.
-!!! related TS6210 tests/cases/conformance/types/rest/genericRestParameters3.ts:27:39: An argument for 'cb' was not provided.
+!!! related TS6210 tests/cases/conformance/types/rest/genericRestParameters3.ts:33:39: An argument for 'cb' was not provided.
     foo<CoolArray<any>>(100);  // Error
                         ~~~
 !!! error TS2345: Argument of type '100' is not assignable to parameter of type '(...args: CoolArray<any>) => void'.
@@ -108,7 +114,7 @@ tests/cases/conformance/types/rest/genericRestParameters3.ts(53,5): error TS2345
                                    ~~
 !!! error TS2345: Argument of type '[10, 20]' is not assignable to parameter of type 'CoolArray<number>'.
 !!! error TS2345:   Property 'hello' is missing in type '[10, 20]' but required in type 'CoolArray<number>'.
-!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:24:5: 'hello' is declared here.
+!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:30:5: 'hello' is declared here.
 
     declare function baz<T>(...args: CoolArray<T>): void;
     declare const ca: CoolArray<number>;
@@ -117,22 +123,22 @@ tests/cases/conformance/types/rest/genericRestParameters3.ts(53,5): error TS2345
     ~~~~~
 !!! error TS2345: Argument of type '[]' is not assignable to parameter of type 'CoolArray<unknown>'.
 !!! error TS2345:   Property 'hello' is missing in type '[]' but required in type 'CoolArray<unknown>'.
-!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:24:5: 'hello' is declared here.
+!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:30:5: 'hello' is declared here.
     baz(1);      // Error
         ~
 !!! error TS2345: Argument of type '[number]' is not assignable to parameter of type 'CoolArray<unknown>'.
 !!! error TS2345:   Property 'hello' is missing in type '[number]' but required in type 'CoolArray<unknown>'.
-!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:24:5: 'hello' is declared here.
+!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:30:5: 'hello' is declared here.
     baz(1, 2);   // Error
         ~
 !!! error TS2345: Argument of type '[number, number]' is not assignable to parameter of type 'CoolArray<unknown>'.
 !!! error TS2345:   Property 'hello' is missing in type '[number, number]' but required in type 'CoolArray<unknown>'.
-!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:24:5: 'hello' is declared here.
+!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:30:5: 'hello' is declared here.
     baz(...ca);  // Error
         ~~~~~
 !!! error TS2345: Argument of type 'number[]' is not assignable to parameter of type 'CoolArray<number>'.
 !!! error TS2345:   Property 'hello' is missing in type 'number[]' but required in type 'CoolArray<number>'.
-!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:24:5: 'hello' is declared here.
+!!! related TS2728 tests/cases/conformance/types/rest/genericRestParameters3.ts:30:5: 'hello' is declared here.
 
     // Repro from #26491
 
@@ -143,4 +149,10 @@ tests/cases/conformance/types/rest/genericRestParameters3.ts(53,5): error TS2345
         ~~~~~~
 !!! error TS2345: Argument of type '["what"]' is not assignable to parameter of type '[] | [number, string]'.
 !!! error TS2345:   Property '1' is missing in type '["what"]' but required in type '[number, string]'.
+    
+    // Repro from #35066
+    
+    declare function foo2(...args: string[] | number[]): void;
+    let x2: ReadonlyArray<string> = ["hello"];
+    foo2(...x2);
 

tests/baselines/reference/genericRestParameters3.js

@@ -4,11 +4,17 @@ declare let f2: (x: string, y: string) => void;
 declare let f3: (x: string, y: number, z: boolean) => void;
 declare let f4: (...args: [string, string] | [string, number, boolean]) => void;
 
-declare const tt: [string] | [number, boolean];
+declare const t1: [string] | [number, boolean];
+declare const t2: readonly [string] | [number, boolean];
+declare const t3: [string] | readonly [number, boolean];
+declare const t4: readonly [string] | readonly [number, boolean];
 
 f1("foo", "abc");
 f1("foo", 10, true);
-f1("foo", ...tt);
+f1("foo", ...t1);
+f1("foo", ...t2);
+f1("foo", ...t3);
+f1("foo", ...t4);
 f1("foo", 10);  // Error
 f1("foo");  // Error
 
@@ -52,6 +58,12 @@ declare function hmm<A extends [] | [number, string]>(...args: A): void;
 hmm(); // okay, A = []
 hmm(1, "s"); // okay, A = [1, "s"]
 hmm("what"); // no error?  A = [] | [number, string] ?
+
+// Repro from #35066
+
+declare function foo2(...args: string[] | number[]): void;
+let x2: ReadonlyArray<string> = ["hello"];
+foo2(...x2);
 
 
 //// [genericRestParameters3.js]
@@ -65,7 +77,10 @@ var __spreadArrays = (this && this.__spreadArrays) || function () {
 };
 f1("foo", "abc");
 f1("foo", 10, true);
-f1.apply(void 0, __spreadArrays(["foo"], tt));
+f1.apply(void 0, __spreadArrays(["foo"], t1));
+f1.apply(void 0, __spreadArrays(["foo"], t2));
+f1.apply(void 0, __spreadArrays(["foo"], t3));
+f1.apply(void 0, __spreadArrays(["foo"], t4));
 f1("foo", 10); // Error
 f1("foo"); // Error
 f2 = f1;
@@ -93,14 +108,19 @@ baz.apply(void 0, ca); // Error
 hmm(); // okay, A = []
 hmm(1, "s"); // okay, A = [1, "s"]
 hmm("what"); // no error?  A = [] | [number, string] ?
+var x2 = ["hello"];
+foo2.apply(void 0, x2);
 
 
 //// [genericRestParameters3.d.ts]
 declare let f1: (x: string, ...args: [string] | [number, boolean]) => void;
 declare let f2: (x: string, y: string) => void;
 declare let f3: (x: string, y: number, z: boolean) => void;
 declare let f4: (...args: [string, string] | [string, number, boolean]) => void;
-declare const tt: [string] | [number, boolean];
+declare const t1: [string] | [number, boolean];
+declare const t2: readonly [string] | [number, boolean];
+declare const t3: [string] | readonly [number, boolean];
+declare const t4: readonly [string] | readonly [number, boolean];
 interface CoolArray<E> extends Array<E> {
     hello: number;
 }
@@ -111,3 +131,5 @@ declare let b: any;
 declare function baz<T>(...args: CoolArray<T>): void;
 declare const ca: CoolArray<number>;
 declare function hmm<A extends [] | [number, string]>(...args: A): void;
+declare function foo2(...args: string[] | number[]): void;
+declare let x2: ReadonlyArray<string>;