Elaborate errors on const asserted expressions (#54396)

Author: Andarist

src/compiler/checker.ts

@@ -24,6 +24,7 @@ import {
     arrayToMultiMap,
     ArrayTypeNode,
     ArrowFunction,
+    AsExpression,
     AssertionExpression,
     AssignmentDeclarationKind,
     AssignmentKind,
@@ -19350,9 +19351,14 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             return true;
         }
         switch (node.kind) {
+            case SyntaxKind.AsExpression:
+                if (!isConstAssertion(node)) {
+                    break;
+                }
+                // fallthrough
             case SyntaxKind.JsxExpression:
             case SyntaxKind.ParenthesizedExpression:
-                return elaborateError((node as ParenthesizedExpression | JsxExpression).expression, source, target, relation, headMessage, containingMessageChain, errorOutputContainer);
+                return elaborateError((node as AsExpression | ParenthesizedExpression | JsxExpression).expression, source, target, relation, headMessage, containingMessageChain, errorOutputContainer);
             case SyntaxKind.BinaryExpression:
                 switch ((node as BinaryExpression).operatorToken.kind) {
                     case SyntaxKind.EqualsToken:

tests/baselines/reference/constAssertions.errors.txt

@@ -2,9 +2,10 @@ tests/cases/conformance/expressions/typeAssertions/constAssertions.ts(44,32): er
 tests/cases/conformance/expressions/typeAssertions/constAssertions.ts(61,10): error TS1355: A 'const' assertions can only be applied to references to enum members, or string, number, boolean, array, or object literals.
 tests/cases/conformance/expressions/typeAssertions/constAssertions.ts(62,10): error TS1355: A 'const' assertions can only be applied to references to enum members, or string, number, boolean, array, or object literals.
 tests/cases/conformance/expressions/typeAssertions/constAssertions.ts(63,10): error TS1355: A 'const' assertions can only be applied to references to enum members, or string, number, boolean, array, or object literals.
+tests/cases/conformance/expressions/typeAssertions/constAssertions.ts(118,3): error TS2322: Type '3' is not assignable to type '2'.
 
 
-==== tests/cases/conformance/expressions/typeAssertions/constAssertions.ts (4 errors) ====
+==== tests/cases/conformance/expressions/typeAssertions/constAssertions.ts (5 errors) ====
     let v1 = 'abc' as const;
     let v2 = `abc` as const;
     let v3 = 10 as const;
@@ -120,4 +121,19 @@ tests/cases/conformance/expressions/typeAssertions/constAssertions.ts(63,10): er
         return [`get-${propName}`, `set-${propName}`] as const;
     }
 
-    const ns1 = accessorNames('foo');
+    const ns1 = accessorNames('foo');
+    
+    // repro from https://github.com/microsoft/TypeScript/issues/54374
+    interface Foo54374 {
+      a: 1;
+      b: 2;
+    }
+    
+    const fooConst54374: Foo54374 = {
+      a: 1,
+      b: 3
+      ~
+!!! error TS2322: Type '3' is not assignable to type '2'.
+!!! related TS6500 tests/cases/conformance/expressions/typeAssertions/constAssertions.ts:113:3: The expected type comes from property 'b' which is declared here on type 'Foo54374'
+    } as const
+    

tests/baselines/reference/constAssertions.js

@@ -106,7 +106,19 @@ function accessorNames<S extends string>(propName: S) {
     return [`get-${propName}`, `set-${propName}`] as const;
 }
 
-const ns1 = accessorNames('foo');
+const ns1 = accessorNames('foo');
+
+// repro from https://github.com/microsoft/TypeScript/issues/54374
+interface Foo54374 {
+  a: 1;
+  b: 2;
+}
+
+const fooConst54374: Foo54374 = {
+  a: 1,
+  b: 3
+} as const
+
 
 //// [constAssertions.js]
 "use strict";
@@ -193,6 +205,10 @@ function accessorNames(propName) {
     return [`get-${propName}`, `set-${propName}`];
 }
 const ns1 = accessorNames('foo');
+const fooConst54374 = {
+    a: 1,
+    b: 3
+};
 
 
 //// [constAssertions.d.ts]
@@ -311,3 +327,8 @@ declare function ff4(verify: boolean, contentMatches: boolean): "verify_match" |
 declare function ff5(verify: boolean, contentMatches: boolean): "verify_match" | "verify_nonMatch" | "write_match" | "write_nonMatch";
 declare function accessorNames<S extends string>(propName: S): readonly [`get-${S}`, `set-${S}`];
 declare const ns1: readonly ["get-foo", "set-foo"];
+interface Foo54374 {
+    a: 1;
+    b: 2;
+}
+declare const fooConst54374: Foo54374;

tests/baselines/reference/constAssertions.symbols

@@ -387,3 +387,27 @@ const ns1 = accessorNames('foo');
 >ns1 : Symbol(ns1, Decl(constAssertions.ts, 107, 5))
 >accessorNames : Symbol(accessorNames, Decl(constAssertions.ts, 101, 1))
 
+// repro from https://github.com/microsoft/TypeScript/issues/54374
+interface Foo54374 {
+>Foo54374 : Symbol(Foo54374, Decl(constAssertions.ts, 107, 33))
+
+  a: 1;
+>a : Symbol(Foo54374.a, Decl(constAssertions.ts, 110, 20))
+
+  b: 2;
+>b : Symbol(Foo54374.b, Decl(constAssertions.ts, 111, 7))
+}
+
+const fooConst54374: Foo54374 = {
+>fooConst54374 : Symbol(fooConst54374, Decl(constAssertions.ts, 115, 5))
+>Foo54374 : Symbol(Foo54374, Decl(constAssertions.ts, 107, 33))
+
+  a: 1,
+>a : Symbol(a, Decl(constAssertions.ts, 115, 33))
+
+  b: 3
+>b : Symbol(b, Decl(constAssertions.ts, 116, 7))
+
+} as const
+>const : Symbol(const)
+

tests/baselines/reference/constAssertions.types

@@ -540,3 +540,27 @@ const ns1 = accessorNames('foo');
 >accessorNames : <S extends string>(propName: S) => readonly [`get-${S}`, `set-${S}`]
 >'foo' : "foo"
 
+// repro from https://github.com/microsoft/TypeScript/issues/54374
+interface Foo54374 {
+  a: 1;
+>a : 1
+
+  b: 2;
+>b : 2
+}
+
+const fooConst54374: Foo54374 = {
+>fooConst54374 : Foo54374
+>{  a: 1,  b: 3} as const : { readonly a: 1; readonly b: 3; }
+>{  a: 1,  b: 3} : { readonly a: 1; readonly b: 3; }
+
+  a: 1,
+>a : 1
+>1 : 1
+
+  b: 3
+>b : 3
+>3 : 3
+
+} as const
+

tests/cases/conformance/expressions/typeAssertions/constAssertions.ts

@@ -109,4 +109,15 @@ function accessorNames<S extends string>(propName: S) {
     return [`get-${propName}`, `set-${propName}`] as const;
 }
 
-const ns1 = accessorNames('foo');
+const ns1 = accessorNames('foo');
+
+// repro from https://github.com/microsoft/TypeScript/issues/54374
+interface Foo54374 {
+  a: 1;
+  b: 2;
+}
+
+const fooConst54374: Foo54374 = {
+  a: 1,
+  b: 3
+} as const