Allow `import =` in module augmentations (#57704)

src/compiler/checker.ts

@@ -47029,6 +47029,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 grammarErrorOnFirstToken(node, Diagnostics.Exports_and_export_assignments_are_not_permitted_in_module_augmentations);
                 break;
             case SyntaxKind.ImportEqualsDeclaration:
+                // import a = e.x; in module augmentation is ok, but not import a = require('fs)
+                if (isInternalModuleImportEqualsDeclaration(node)) break;
+                // falls through
             case SyntaxKind.ImportDeclaration:
                 grammarErrorOnFirstToken(node, Diagnostics.Imports_are_not_permitted_in_module_augmentations_Consider_moving_them_to_the_enclosing_external_module);
                 break;

tests/baselines/reference/importAliasInModuleAugmentation.errors.txt

@@ -0,0 +1,26 @@
+importAliasInModuleAugmentation.ts(12,5): error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
+importAliasInModuleAugmentation.ts(12,24): error TS2307: Cannot find module 'fs' or its corresponding type declarations.
+
+
+==== importAliasInModuleAugmentation.ts (2 errors) ====
+    export { }
+    
+    namespace A {
+        export const y = 34;
+        export interface y { s: string }
+    }
+    
+    declare global {
+        export import x = A.y;
+    
+        // Should still error
+        import f = require("fs");
+        ~~~~~~
+!!! error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
+                           ~~~~
+!!! error TS2307: Cannot find module 'fs' or its corresponding type declarations.
+    }
+    
+    const m: number = x;
+    let s: x = { s: "" };
+    void s.s;

tests/baselines/reference/importAliasInModuleAugmentation.js

@@ -0,0 +1,31 @@
+//// [tests/cases/compiler/importAliasInModuleAugmentation.ts] ////
+
+//// [importAliasInModuleAugmentation.ts]
+export { }
+
+namespace A {
+    export const y = 34;
+    export interface y { s: string }
+}
+
+declare global {
+    export import x = A.y;
+
+    // Should still error
+    import f = require("fs");
+}
+
+const m: number = x;
+let s: x = { s: "" };
+void s.s;
+
+//// [importAliasInModuleAugmentation.js]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+var A;
+(function (A) {
+    A.y = 34;
+})(A || (A = {}));
+var m = x;
+var s = { s: "" };
+void s.s;

tests/baselines/reference/importAliasInModuleAugmentation.symbols

@@ -0,0 +1,43 @@
+//// [tests/cases/compiler/importAliasInModuleAugmentation.ts] ////
+
+=== importAliasInModuleAugmentation.ts ===
+export { }
+
+namespace A {
+>A : Symbol(A, Decl(importAliasInModuleAugmentation.ts, 0, 10))
+
+    export const y = 34;
+>y : Symbol(y, Decl(importAliasInModuleAugmentation.ts, 3, 16), Decl(importAliasInModuleAugmentation.ts, 3, 24))
+
+    export interface y { s: string }
+>y : Symbol(y, Decl(importAliasInModuleAugmentation.ts, 3, 16), Decl(importAliasInModuleAugmentation.ts, 3, 24))
+>s : Symbol(y.s, Decl(importAliasInModuleAugmentation.ts, 4, 24))
+}
+
+declare global {
+>global : Symbol(global, Decl(importAliasInModuleAugmentation.ts, 5, 1))
+
+    export import x = A.y;
+>x : Symbol(x, Decl(importAliasInModuleAugmentation.ts, 7, 16))
+>A : Symbol(A, Decl(importAliasInModuleAugmentation.ts, 0, 10))
+>y : Symbol(x, Decl(importAliasInModuleAugmentation.ts, 3, 16), Decl(importAliasInModuleAugmentation.ts, 3, 24))
+
+    // Should still error
+    import f = require("fs");
+>f : Symbol(f, Decl(importAliasInModuleAugmentation.ts, 8, 26))
+}
+
+const m: number = x;
+>m : Symbol(m, Decl(importAliasInModuleAugmentation.ts, 14, 5))
+>x : Symbol(x, Decl(importAliasInModuleAugmentation.ts, 7, 16))
+
+let s: x = { s: "" };
+>s : Symbol(s, Decl(importAliasInModuleAugmentation.ts, 15, 3))
+>x : Symbol(x, Decl(importAliasInModuleAugmentation.ts, 7, 16))
+>s : Symbol(s, Decl(importAliasInModuleAugmentation.ts, 15, 12))
+
+void s.s;
+>s.s : Symbol(x.s, Decl(importAliasInModuleAugmentation.ts, 4, 24))
+>s : Symbol(s, Decl(importAliasInModuleAugmentation.ts, 15, 3))
+>s : Symbol(x.s, Decl(importAliasInModuleAugmentation.ts, 4, 24))
+

tests/baselines/reference/importAliasInModuleAugmentation.types

@@ -0,0 +1,45 @@
+//// [tests/cases/compiler/importAliasInModuleAugmentation.ts] ////
+
+=== importAliasInModuleAugmentation.ts ===
+export { }
+
+namespace A {
+>A : typeof A
+
+    export const y = 34;
+>y : 34
+>34 : 34
+
+    export interface y { s: string }
+>s : string
+}
+
+declare global {
+>global : typeof global
+
+    export import x = A.y;
+>x : 34
+>A : typeof A
+>y : x
+
+    // Should still error
+    import f = require("fs");
+>f : any
+}
+
+const m: number = x;
+>m : number
+>x : 34
+
+let s: x = { s: "" };
+>s : x
+>{ s: "" } : { s: string; }
+>s : string
+>"" : ""
+
+void s.s;
+>void s.s : undefined
+>s.s : string
+>s : x
+>s : string
+

tests/baselines/reference/moduleAugmentationImportsAndExports2.errors.txt

@@ -3,8 +3,6 @@ f3.ts(11,5): error TS2667: Imports are not permitted in module augmentations. Co
 f3.ts(11,21): error TS2307: Cannot find module './f2' or its corresponding type declarations.
 f3.ts(12,5): error TS2666: Exports and export assignments are not permitted in module augmentations.
 f3.ts(12,21): error TS2307: Cannot find module './f2' or its corresponding type declarations.
-f3.ts(13,5): error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
-f3.ts(14,5): error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
 f4.ts(5,11): error TS2339: Property 'foo' does not exist on type 'A'.
 
 
@@ -16,7 +14,7 @@ f4.ts(5,11): error TS2339: Property 'foo' does not exist on type 'A'.
         n: number;
     }
     
-==== f3.ts (7 errors) ====
+==== f3.ts (5 errors) ====
     import {A} from "./f1";
     
     A.prototype.foo = function () { return undefined; }
@@ -40,11 +38,7 @@ f4.ts(5,11): error TS2339: Property 'foo' does not exist on type 'A'.
                         ~~~~~~
 !!! error TS2307: Cannot find module './f2' or its corresponding type declarations.
         import I = N.Ifc;
-        ~~~~~~
-!!! error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
         import C = N.Cls;
-        ~~~~~~
-!!! error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
         // should have explicit export
         interface A {
             foo(): B;

tests/baselines/reference/moduleAugmentationImportsAndExports3.errors.txt

@@ -1,7 +1,5 @@
 f3.ts(11,5): error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
 f3.ts(11,21): error TS2307: Cannot find module './f2' or its corresponding type declarations.
-f3.ts(12,5): error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
-f3.ts(13,5): error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
 
 
 ==== f1.ts (0 errors) ====
@@ -12,7 +10,7 @@ f3.ts(13,5): error TS2667: Imports are not permitted in module augmentations. Co
         n: number;
     }
     
-==== f3.ts (4 errors) ====
+==== f3.ts (2 errors) ====
     import {A} from "./f1";
     
     A.prototype.foo = function () { return undefined; }
@@ -29,11 +27,7 @@ f3.ts(13,5): error TS2667: Imports are not permitted in module augmentations. Co
                         ~~~~~~
 !!! error TS2307: Cannot find module './f2' or its corresponding type declarations.
         import I = N.Ifc;
-        ~~~~~~
-!!! error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
         import C = N.Cls;
-        ~~~~~~
-!!! error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
         interface A {
             foo(): B;
             bar(): I;

tests/baselines/reference/newNamesInGlobalAugmentations1.errors.txt

@@ -1,24 +0,0 @@
-f1.d.ts(12,5): error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
-
-
-==== f1.d.ts (1 errors) ====
-    export {};
-    
-    declare module M.M1 {
-        export let x: number;
-    }
-    declare global {
-        interface SymbolConstructor {
-            observable: symbol;
-        }
-        class Cls {x}
-        let [a, b]: number[];
-        export import X = M.M1.x;
-        ~~~~~~
-!!! error TS2667: Imports are not permitted in module augmentations. Consider moving them to the enclosing external module.
-    }
-    
-==== main.ts (0 errors) ====
-    Symbol.observable;
-    new Cls().x
-    let c = a + b + X;

tests/cases/compiler/importAliasInModuleAugmentation.ts

@@ -0,0 +1,17 @@
+export { }
+
+namespace A {
+    export const y = 34;
+    export interface y { s: string }
+}
+
+declare global {
+    export import x = A.y;
+
+    // Should still error
+    import f = require("fs");
+}
+
+const m: number = x;
+let s: x = { s: "" };
+void s.s;