fix type checking of variables named "exports" (microsoft#52209)

Author: Tobias-Scholz

src/compiler/checker.ts

@@ -36500,7 +36500,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 if (checkReferenceExpression(left,
                     Diagnostics.The_left_hand_side_of_an_assignment_expression_must_be_a_variable_or_a_property_access,
                     Diagnostics.The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access)
-                    && (!isIdentifier(left) || unescapeLeadingUnderscores(left.escapedText) !== "exports")) {
+                    ) {
 
                     let headMessage: DiagnosticMessage | undefined;
                     if (exactOptionalPropertyTypes && isPropertyAccessExpression(left) && maybeTypeOfKind(valueType, TypeFlags.Undefined)) {

tests/baselines/reference/typeCheckExportsVariable.errors.txt

@@ -0,0 +1,8 @@
+tests/cases/compiler/typeCheckExportsVariable.ts(2,1): error TS2322: Type 'string' is not assignable to type 'number'.
+
+
+==== tests/cases/compiler/typeCheckExportsVariable.ts (1 errors) ====
+    let exports: number;
+    exports = '';
+    ~~~~~~~
+!!! error TS2322: Type 'string' is not assignable to type 'number'.

tests/baselines/reference/typeCheckExportsVariable.js

@@ -0,0 +1,7 @@
+//// [typeCheckExportsVariable.ts]
+let exports: number;
+exports = '';
+
+//// [typeCheckExportsVariable.js]
+var exports;
+exports = '';

tests/baselines/reference/typeCheckExportsVariable.symbols

@@ -0,0 +1,7 @@
+=== tests/cases/compiler/typeCheckExportsVariable.ts ===
+let exports: number;
+>exports : Symbol(exports, Decl(typeCheckExportsVariable.ts, 0, 3))
+
+exports = '';
+>exports : Symbol(exports, Decl(typeCheckExportsVariable.ts, 0, 3))
+

tests/baselines/reference/typeCheckExportsVariable.types

@@ -0,0 +1,9 @@
+=== tests/cases/compiler/typeCheckExportsVariable.ts ===
+let exports: number;
+>exports : number
+
+exports = '';
+>exports = '' : ""
+>exports : number
+>'' : ""
+

tests/cases/compiler/typeCheckExportsVariable.ts

@@ -0,0 +1,3 @@
+
+let exports: number;
+exports = '';