Update based on microsoft#57686

Author: frigus02

src/compiler/checker.ts

@@ -719,6 +719,8 @@ import {
     isStringOrNumericLiteralLike,
     isSuperCall,
     isSuperProperty,
+    isSyntacticallyNumeric,
+    isSyntacticallyString,
     isTaggedTemplateExpression,
     isTemplateSpan,
     isThisContainerOrFunctionBlock,
@@ -45595,44 +45597,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         return value;
     }
 
-    function isSyntacticallyNumeric(expr: Expression): boolean {
-        switch (expr.kind) {
-            case SyntaxKind.PrefixUnaryExpression:
-                return isSyntacticallyNumeric((expr as PrefixUnaryExpression).operand);
-            case SyntaxKind.BinaryExpression:
-                return isSyntacticallyNumeric((expr as BinaryExpression).left) && isSyntacticallyNumeric((expr as BinaryExpression).right);
-            case SyntaxKind.ParenthesizedExpression:
-                return isSyntacticallyNumeric((expr as ParenthesizedExpression).expression);
-            case SyntaxKind.NumericLiteral:
-                return true;
-        }
-        return false;
-    }
-
-    function isSyntacticallyString(expr: Expression): boolean {
-        switch (expr.kind) {
-            case SyntaxKind.BinaryExpression:
-                const left = (expr as BinaryExpression).left;
-                const right = (expr as BinaryExpression).right;
-                const leftIsNumeric = isSyntacticallyNumeric(left);
-                const rightIsNumeric = isSyntacticallyNumeric(right);
-                return (
-                    !(leftIsNumeric && rightIsNumeric) &&
-                    (isSyntacticallyString(left) || leftIsNumeric) &&
-                    (isSyntacticallyString(right) || rightIsNumeric) &&
-                    (expr as BinaryExpression).operatorToken.kind === SyntaxKind.PlusToken
-                );
-            case SyntaxKind.TemplateExpression:
-                return (expr as TemplateExpression).templateSpans.every(span => isSyntacticallyString(span.expression));
-            case SyntaxKind.ParenthesizedExpression:
-                return isSyntacticallyString((expr as ParenthesizedExpression).expression);
-            case SyntaxKind.StringLiteral:
-            case SyntaxKind.NoSubstitutionTemplateLiteral:
-                return true;
-        }
-        return false;
-    }
-
     function evaluate(expr: Expression, location?: Declaration): string | number | undefined {
         switch (expr.kind) {
             case SyntaxKind.PrefixUnaryExpression:

src/compiler/utilities.ts

@@ -10657,3 +10657,17 @@ export function isSyntacticallyString(expr: Expression): boolean {
     }
     return false;
 }
+
+/** @internal */
+export function isSyntacticallyNumeric(expr: Expression): boolean {
+    expr = skipOuterExpressions(expr);
+    switch (expr.kind) {
+        case SyntaxKind.PrefixUnaryExpression:
+            return isSyntacticallyNumeric((expr as PrefixUnaryExpression).operand);
+        case SyntaxKind.BinaryExpression:
+            return isSyntacticallyNumeric((expr as BinaryExpression).left) && isSyntacticallyNumeric((expr as BinaryExpression).right);
+        case SyntaxKind.NumericLiteral:
+            return true;
+    }
+    return false;
+}

tests/baselines/reference/enumWithNonLiteralStringInitializer.errors.txt

@@ -3,18 +3,20 @@ bad.ts(3,8): error TS18055: A string member initializer in a enum declaration ca
 
 ==== ./helpers.ts (0 errors) ====
     export const foo = 2;
+    export const bar = "bar";
 
 ==== ./bad.ts (1 errors) ====
-    import { foo } from "./helpers";
+    import { bar } from "./helpers";
     enum A {
-       a = `${foo}`
-           ~~~~~~~~
+       a = bar,
+           ~~~
 !!! error TS18055: A string member initializer in a enum declaration can only use constant expressions when 'isolatedModules' is enabled.
     }
 
 ==== ./good.ts (0 errors) ====
+    import { foo } from "./helpers";
     enum A {
-       a = `${"foo"}`,
+       a = `${foo}`,
        b = "" + 2,
        c = 2 + "",
        d = ("foo"),

tests/baselines/reference/enumWithNonLiteralStringInitializer.js

@@ -2,16 +2,18 @@
 
 //// [helpers.ts]
 export const foo = 2;
+export const bar = "bar";
 
 //// [bad.ts]
-import { foo } from "./helpers";
+import { bar } from "./helpers";
 enum A {
-   a = `${foo}`
+   a = bar,
 }
 
 //// [good.ts]
+import { foo } from "./helpers";
 enum A {
-   a = `${"foo"}`,
+   a = `${foo}`,
    b = "" + 2,
    c = 2 + "",
    d = ("foo"),
@@ -21,20 +23,24 @@ enum A {
 //// [helpers.js]
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
-exports.foo = void 0;
+exports.bar = exports.foo = void 0;
 exports.foo = 2;
+exports.bar = "bar";
 //// [bad.js]
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });
 var helpers_1 = require("./helpers");
 var A;
 (function (A) {
-    A["a"] = "2";
+    A["a"] = "bar";
 })(A || (A = {}));
 //// [good.js]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+var helpers_1 = require("./helpers");
 var A;
 (function (A) {
-    A["a"] = "foo";
+    A["a"] = "2";
     A["b"] = "2";
     A["c"] = "2";
     A["d"] = "foo";

tests/cases/compiler/enumWithNonLiteralStringInitializer.ts

@@ -3,16 +3,18 @@
 
 // @filename: ./helpers.ts
 export const foo = 2;
+export const bar = "bar";
 
 // @filename: ./bad.ts
-import { foo } from "./helpers";
+import { bar } from "./helpers";
 enum A {
-   a = `${foo}`
+   a = bar,
 }
 
 // @filename: ./good.ts
+import { foo } from "./helpers";
 enum A {
-   a = `${"foo"}`,
+   a = `${foo}`,
    b = "" + 2,
    c = 2 + "",
    d = ("foo"),