[wontfix] fix(checker): Allow element access expressions in computed property names if argument is literal

src/compiler/checker.ts

@@ -744,6 +744,7 @@ import {
     isShorthandAmbientModuleSymbol,
     isShorthandPropertyAssignment,
     isSideEffectImport,
+    isSignedNumericLiteral,
     isSingleOrDoubleQuote,
     isSourceFile,
     isSourceFileJS,
@@ -13787,14 +13788,25 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             && isTypeUsableAsIndexSignature(isComputedPropertyName(node) ? checkComputedPropertyName(node) : checkExpressionCached((node as ElementAccessExpression).argumentExpression));
     }
 
-    function isLateBindableAST(node: DeclarationName) {
-        if (!isComputedPropertyName(node) && !isElementAccessExpression(node)) {
-            return false;
+    function isLateBindableExpression(expr: Expression): boolean {
+        while (isElementAccessExpression(expr)) {
+            const argument = skipParentheses(expr.argumentExpression);
+            if (!isStringOrNumericLiteralLike(argument) && !isSignedNumericLiteral(argument)) return false;
+            expr = expr.expression;
         }
-        const expr = isComputedPropertyName(node) ? node.expression : node.argumentExpression;
         return isEntityNameExpression(expr);
     }
 
+    function isLateBindableAST(node: DeclarationName) {
+        if (isComputedPropertyName(node)) {
+            return isLateBindableExpression(node.expression);
+        }
+        else if (isElementAccessExpression(node)) {
+            return isLateBindableExpression(node);
+        }
+        return false;
+    }
+
     function isTypeUsableAsIndexSignature(type: Type): boolean {
         return isTypeAssignableTo(type, stringNumberSymbolType);
     }

src/compiler/utilities.ts

@@ -2352,7 +2352,9 @@ export function getNameFromIndexInfo(info: IndexInfo): string | undefined {
 
 /** @internal */
 export function isComputedNonLiteralName(name: PropertyName): boolean {
-    return name.kind === SyntaxKind.ComputedPropertyName && !isStringOrNumericLiteralLike(name.expression);
+    return name.kind === SyntaxKind.ComputedPropertyName &&
+        !isStringOrNumericLiteralLike(name.expression) &&
+        !isSignedNumericLiteral(name.expression);
 }
 
 /** @internal */
@@ -2368,6 +2370,12 @@ export function tryGetTextOfPropertyName(name: PropertyName | NoSubstitutionTemp
             return escapeLeadingUnderscores(name.text);
         case SyntaxKind.ComputedPropertyName:
             if (isStringOrNumericLiteralLike(name.expression)) return escapeLeadingUnderscores(name.expression.text);
+            if (isSignedNumericLiteral(name.expression)) {
+                if (name.expression.operator === SyntaxKind.MinusToken) {
+                    return tokenToString(name.expression.operator) + name.expression.operand.text as __String;
+                }
+                return name.expression.operand.text as __String;
+            }
             return undefined;
         case SyntaxKind.JsxNamespacedName:
             return getEscapedTextOfJsxNamespacedName(name);
@@ -2817,7 +2825,7 @@ export function isPartOfTypeNode(node: Node): boolean {
             }
             // At this point, node is either a qualified name or an identifier
             Debug.assert(node.kind === SyntaxKind.Identifier || node.kind === SyntaxKind.QualifiedName || node.kind === SyntaxKind.PropertyAccessExpression, "'node' was expected to be a qualified name, identifier or property access in 'isPartOfTypeNode'.");
-            // falls through
+        // falls through
 
         case SyntaxKind.QualifiedName:
         case SyntaxKind.PropertyAccessExpression:
@@ -3221,7 +3229,7 @@ export function getThisContainer(node: Node, includeArrowFunctions: boolean, inc
                 if (!includeArrowFunctions) {
                     continue;
                 }
-                // falls through
+            // falls through
 
             case SyntaxKind.FunctionDeclaration:
             case SyntaxKind.FunctionExpression:
@@ -3346,7 +3354,7 @@ export function getSuperContainer(node: Node, stopOnFunctions: boolean) {
                 if (!stopOnFunctions) {
                     continue;
                 }
-                // falls through
+            // falls through
 
             case SyntaxKind.PropertyDeclaration:
             case SyntaxKind.PropertySignature:
@@ -3682,7 +3690,7 @@ export function isExpressionNode(node: Node): boolean {
             if (node.parent.kind === SyntaxKind.TypeQuery || isJSDocLinkLike(node.parent) || isJSDocNameReference(node.parent) || isJSDocMemberName(node.parent) || isJSXTagName(node)) {
                 return true;
             }
-            // falls through
+        // falls through
 
         case SyntaxKind.NumericLiteral:
         case SyntaxKind.BigIntLiteral:
@@ -5078,7 +5086,7 @@ export function getDeclarationFromName(name: Node): Declaration | undefined {
         case SyntaxKind.NoSubstitutionTemplateLiteral:
         case SyntaxKind.NumericLiteral:
             if (isComputedPropertyName(parent)) return parent.parent;
-            // falls through
+        // falls through
         case SyntaxKind.Identifier:
             if (isDeclaration(parent)) {
                 return parent.name === name ? parent : undefined;
@@ -5323,7 +5331,7 @@ export function getFunctionFlags(node: SignatureDeclaration | undefined): Functi
             if (node.asteriskToken) {
                 flags |= FunctionFlags.Generator;
             }
-            // falls through
+        // falls through
 
         case SyntaxKind.ArrowFunction:
             if (hasSyntacticModifier(node, ModifierFlags.Async)) {
@@ -8435,7 +8443,7 @@ export function getLeftmostExpression(node: Expression, stopAtCallExpressions: b
                 if (stopAtCallExpressions) {
                     return node;
                 }
-                // falls through
+            // falls through
             case SyntaxKind.AsExpression:
             case SyntaxKind.ElementAccessExpression:
             case SyntaxKind.PropertyAccessExpression:
@@ -11593,7 +11601,7 @@ export function createNameResolver({
             switch (location.kind) {
                 case SyntaxKind.SourceFile:
                     if (!isExternalOrCommonJsModule(location as SourceFile)) break;
-                    // falls through
+                // falls through
                 case SyntaxKind.ModuleDeclaration:
                     const moduleExports = getSymbolOfDeclaration(location as SourceFile | ModuleDeclaration)?.exports || emptySymbols;
                     if (location.kind === SyntaxKind.SourceFile || (isModuleDeclaration(location) && location.flags & NodeFlags.Ambient && !isGlobalScopeAugmentation(location))) {
@@ -11739,7 +11747,7 @@ export function createNameResolver({
                     if (getEmitScriptTarget(compilerOptions) >= ScriptTarget.ES2015) {
                         break;
                     }
-                    // falls through
+                // falls through
                 case SyntaxKind.MethodDeclaration:
                 case SyntaxKind.Constructor:
                 case SyntaxKind.GetAccessor:

tests/baselines/reference/declarationEmitLateBoundAssignments.errors.txt

@@ -0,0 +1,58 @@
+declarationEmitLateBoundAssignments.ts(4,1): error TS7053: Element implicitly has an 'any' type because expression of type 'unique symbol' can't be used to index type 'typeof foo'.
+  Property '[_private]' does not exist on type 'typeof foo'.
+declarationEmitLateBoundAssignments.ts(6,1): error TS7053: Element implicitly has an 'any' type because expression of type '"strMemName"' can't be used to index type 'typeof foo'.
+  Property 'strMemName' does not exist on type 'typeof foo'.
+declarationEmitLateBoundAssignments.ts(8,1): error TS7053: Element implicitly has an 'any' type because expression of type '"dashed-str-mem"' can't be used to index type 'typeof foo'.
+  Property 'dashed-str-mem' does not exist on type 'typeof foo'.
+declarationEmitLateBoundAssignments.ts(10,1): error TS7053: Element implicitly has an 'any' type because expression of type '42' can't be used to index type 'typeof foo'.
+  Property '42' does not exist on type 'typeof foo'.
+declarationEmitLateBoundAssignments.ts(12,19): error TS7053: Element implicitly has an 'any' type because expression of type 'unique symbol' can't be used to index type 'typeof foo'.
+  Property '[_private]' does not exist on type 'typeof foo'.
+declarationEmitLateBoundAssignments.ts(13,19): error TS7053: Element implicitly has an 'any' type because expression of type '"strMemName"' can't be used to index type 'typeof foo'.
+  Property 'strMemName' does not exist on type 'typeof foo'.
+declarationEmitLateBoundAssignments.ts(14,19): error TS7053: Element implicitly has an 'any' type because expression of type '42' can't be used to index type 'typeof foo'.
+  Property '42' does not exist on type 'typeof foo'.
+declarationEmitLateBoundAssignments.ts(15,19): error TS7053: Element implicitly has an 'any' type because expression of type '"dashed-str-mem"' can't be used to index type 'typeof foo'.
+  Property 'dashed-str-mem' does not exist on type 'typeof foo'.
+
+
+==== declarationEmitLateBoundAssignments.ts (8 errors) ====
+    export function foo() {}
+    foo.bar = 12;
+    const _private = Symbol();
+    foo[_private] = "ok";
+    ~~~~~~~~~~~~~
+!!! error TS7053: Element implicitly has an 'any' type because expression of type 'unique symbol' can't be used to index type 'typeof foo'.
+!!! error TS7053:   Property '[_private]' does not exist on type 'typeof foo'.
+    const strMem = "strMemName";
+    foo[strMem] = "ok";
+    ~~~~~~~~~~~
+!!! error TS7053: Element implicitly has an 'any' type because expression of type '"strMemName"' can't be used to index type 'typeof foo'.
+!!! error TS7053:   Property 'strMemName' does not exist on type 'typeof foo'.
+    const dashStrMem = "dashed-str-mem";
+    foo[dashStrMem] = "ok";
+    ~~~~~~~~~~~~~~~
+!!! error TS7053: Element implicitly has an 'any' type because expression of type '"dashed-str-mem"' can't be used to index type 'typeof foo'.
+!!! error TS7053:   Property 'dashed-str-mem' does not exist on type 'typeof foo'.
+    const numMem = 42;
+    foo[numMem] = "ok";
+    ~~~~~~~~~~~
+!!! error TS7053: Element implicitly has an 'any' type because expression of type '42' can't be used to index type 'typeof foo'.
+!!! error TS7053:   Property '42' does not exist on type 'typeof foo'.
+
+    const x: string = foo[_private];
+                      ~~~~~~~~~~~~~
+!!! error TS7053: Element implicitly has an 'any' type because expression of type 'unique symbol' can't be used to index type 'typeof foo'.
+!!! error TS7053:   Property '[_private]' does not exist on type 'typeof foo'.
+    const y: string = foo[strMem];
+                      ~~~~~~~~~~~
+!!! error TS7053: Element implicitly has an 'any' type because expression of type '"strMemName"' can't be used to index type 'typeof foo'.
+!!! error TS7053:   Property 'strMemName' does not exist on type 'typeof foo'.
+    const z: string = foo[numMem];
+                      ~~~~~~~~~~~
+!!! error TS7053: Element implicitly has an 'any' type because expression of type '42' can't be used to index type 'typeof foo'.
+!!! error TS7053:   Property '42' does not exist on type 'typeof foo'.
+    const a: string = foo[dashStrMem];
+                      ~~~~~~~~~~~~~~~
+!!! error TS7053: Element implicitly has an 'any' type because expression of type '"dashed-str-mem"' can't be used to index type 'typeof foo'.
+!!! error TS7053:   Property 'dashed-str-mem' does not exist on type 'typeof foo'.

tests/baselines/reference/declarationEmitLateBoundAssignments.js

@@ -38,5 +38,4 @@ const a = foo[dashStrMem];
 export declare function foo(): void;
 export declare namespace foo {
     var bar: number;
-    var strMemName: string;
 }

tests/baselines/reference/declarationEmitLateBoundAssignments.types

@@ -28,8 +28,8 @@ const _private = Symbol();
 foo[_private] = "ok";
 >foo[_private] = "ok" : "ok"
 >                     : ^^^^
->foo[_private] : string
->              : ^^^^^^
+>foo[_private] : any
+>              : ^^^
 >foo : typeof foo
 >    : ^^^^^^^^^^
 >_private : unique symbol
@@ -46,8 +46,8 @@ const strMem = "strMemName";
 foo[strMem] = "ok";
 >foo[strMem] = "ok" : "ok"
 >                   : ^^^^
->foo[strMem] : string
->            : ^^^^^^
+>foo[strMem] : any
+>            : ^^^
 >foo : typeof foo
 >    : ^^^^^^^^^^
 >strMem : "strMemName"
@@ -64,8 +64,8 @@ const dashStrMem = "dashed-str-mem";
 foo[dashStrMem] = "ok";
 >foo[dashStrMem] = "ok" : "ok"
 >                       : ^^^^
->foo[dashStrMem] : string
->                : ^^^^^^
+>foo[dashStrMem] : any
+>                : ^^^
 >foo : typeof foo
 >    : ^^^^^^^^^^
 >dashStrMem : "dashed-str-mem"
@@ -82,8 +82,8 @@ const numMem = 42;
 foo[numMem] = "ok";
 >foo[numMem] = "ok" : "ok"
 >                   : ^^^^
->foo[numMem] : string
->            : ^^^^^^
+>foo[numMem] : any
+>            : ^^^
 >foo : typeof foo
 >    : ^^^^^^^^^^
 >numMem : 42
@@ -94,8 +94,8 @@ foo[numMem] = "ok";
 const x: string = foo[_private];
 >x : string
 >  : ^^^^^^
->foo[_private] : string
->              : ^^^^^^
+>foo[_private] : any
+>              : ^^^
 >foo : typeof foo
 >    : ^^^^^^^^^^
 >_private : unique symbol
@@ -104,8 +104,8 @@ const x: string = foo[_private];
 const y: string = foo[strMem];
 >y : string
 >  : ^^^^^^
->foo[strMem] : string
->            : ^^^^^^
+>foo[strMem] : any
+>            : ^^^
 >foo : typeof foo
 >    : ^^^^^^^^^^
 >strMem : "strMemName"
@@ -114,8 +114,8 @@ const y: string = foo[strMem];
 const z: string = foo[numMem];
 >z : string
 >  : ^^^^^^
->foo[numMem] : string
->            : ^^^^^^
+>foo[numMem] : any
+>            : ^^^
 >foo : typeof foo
 >    : ^^^^^^^^^^
 >numMem : 42
@@ -124,8 +124,8 @@ const z: string = foo[numMem];
 const a: string = foo[dashStrMem];
 >a : string
 >  : ^^^^^^
->foo[dashStrMem] : string
->                : ^^^^^^
+>foo[dashStrMem] : any
+>                : ^^^
 >foo : typeof foo
 >    : ^^^^^^^^^^
 >dashStrMem : "dashed-str-mem"