From 8fdbd54160e5a6796a2c2522222553e79d61ec7c Mon Sep 17 00:00:00 2001
From: TypeScript Bot <23042052+typescript-bot@users.noreply.github.com>
Date: Tue, 25 Feb 2025 22:46:11 -0800
Subject: [PATCH] =?UTF-8?q?=F0=9F=A4=96=20Pick=20PR=20#61210=20(Fix=20mist?=
 =?UTF-8?q?akenly=20disallowed=20default=20e...)=20into=20release-5.8=20(#?=
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Co-authored-by: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
---
 src/compiler/checker.ts                              |  2 +-
 .../reference/erasableSyntaxOnly.errors.txt          |  5 +++++
 tests/baselines/reference/erasableSyntaxOnly.js      |  8 ++++++++
 tests/baselines/reference/erasableSyntaxOnly.symbols |  8 ++++++++
 tests/baselines/reference/erasableSyntaxOnly.types   | 12 ++++++++++++
 .../erasableSyntaxOnlyDeclaration.errors.txt         |  5 +++++
 .../reference/erasableSyntaxOnlyDeclaration.symbols  |  8 ++++++++
 .../reference/erasableSyntaxOnlyDeclaration.types    | 12 ++++++++++++
 tests/cases/compiler/erasableSyntaxOnly.ts           |  5 +++++
 .../cases/compiler/erasableSyntaxOnlyDeclaration.ts  |  5 +++++
 10 files changed, 69 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index abd6fd4bf2e8d..8797dbbf80137 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -47974,7 +47974,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             return;
         }
 
-        if (compilerOptions.erasableSyntaxOnly && !(node.flags & NodeFlags.Ambient)) {
+        if (compilerOptions.erasableSyntaxOnly && node.isExportEquals && !(node.flags & NodeFlags.Ambient)) {
             error(node, Diagnostics.This_syntax_is_not_allowed_when_erasableSyntaxOnly_is_enabled);
         }
         const container = node.parent.kind === SyntaxKind.SourceFile ? node.parent : node.parent.parent as ModuleDeclaration;
diff --git a/tests/baselines/reference/erasableSyntaxOnly.errors.txt b/tests/baselines/reference/erasableSyntaxOnly.errors.txt
index 39a724aa00c51..2005ef65de8e7 100644
--- a/tests/baselines/reference/erasableSyntaxOnly.errors.txt
+++ b/tests/baselines/reference/erasableSyntaxOnly.errors.txt
@@ -104,4 +104,9 @@ index.ts(28,12): error TS1294: This syntax is not allowed when 'erasableSyntaxOn
 ==== other.d.cts (0 errors) ====
     declare function foo(): void;
     export = foo;
+    
+    
+==== esm.mts (0 errors) ====
+    const foo = 1234;
+    export default foo;
     
\ No newline at end of file
diff --git a/tests/baselines/reference/erasableSyntaxOnly.js b/tests/baselines/reference/erasableSyntaxOnly.js
index 1d7393620df4d..9edf749d7b038 100644
--- a/tests/baselines/reference/erasableSyntaxOnly.js
+++ b/tests/baselines/reference/erasableSyntaxOnly.js
@@ -74,6 +74,11 @@ export = foo;
 //// [other.d.cts]
 declare function foo(): void;
 export = foo;
+
+
+//// [esm.mts]
+const foo = 1234;
+export default foo;
 
 
 //// [index.js]
@@ -119,3 +124,6 @@ var MyClassOk = /** @class */ (function () {
 "use strict";
 var foo = require("./other.cjs");
 module.exports = foo;
+//// [esm.mjs]
+var foo = 1234;
+export default foo;
diff --git a/tests/baselines/reference/erasableSyntaxOnly.symbols b/tests/baselines/reference/erasableSyntaxOnly.symbols
index f0220004341b3..8e057dc990217 100644
--- a/tests/baselines/reference/erasableSyntaxOnly.symbols
+++ b/tests/baselines/reference/erasableSyntaxOnly.symbols
@@ -133,3 +133,11 @@ declare function foo(): void;
 export = foo;
 >foo : Symbol(foo, Decl(other.d.cts, 0, 0))
 
+
+=== esm.mts ===
+const foo = 1234;
+>foo : Symbol(foo, Decl(esm.mts, 0, 5))
+
+export default foo;
+>foo : Symbol(foo, Decl(esm.mts, 0, 5))
+
diff --git a/tests/baselines/reference/erasableSyntaxOnly.types b/tests/baselines/reference/erasableSyntaxOnly.types
index 599a8d2125ead..4d4ddaea49701 100644
--- a/tests/baselines/reference/erasableSyntaxOnly.types
+++ b/tests/baselines/reference/erasableSyntaxOnly.types
@@ -179,3 +179,15 @@ export = foo;
 >foo : () => void
 >    : ^^^^^^    
 
+
+=== esm.mts ===
+const foo = 1234;
+>foo : 1234
+>    : ^^^^
+>1234 : 1234
+>     : ^^^^
+
+export default foo;
+>foo : 1234
+>    : ^^^^
+
diff --git a/tests/baselines/reference/erasableSyntaxOnlyDeclaration.errors.txt b/tests/baselines/reference/erasableSyntaxOnlyDeclaration.errors.txt
index 7bc78e382b7ed..fdb4d96f8498b 100644
--- a/tests/baselines/reference/erasableSyntaxOnlyDeclaration.errors.txt
+++ b/tests/baselines/reference/erasableSyntaxOnlyDeclaration.errors.txt
@@ -65,4 +65,9 @@ index.d.ts(1,1): error TS1046: Top-level declarations in .d.ts files must start
 ==== other.d.cts (0 errors) ====
     declare function foo(): void;
     export = foo;
+    
+    
+==== esm.d.mts (0 errors) ====
+    declare const foo = 1234;
+    export default foo;
     
\ No newline at end of file
diff --git a/tests/baselines/reference/erasableSyntaxOnlyDeclaration.symbols b/tests/baselines/reference/erasableSyntaxOnlyDeclaration.symbols
index 4f439b211c5c3..2763999d6468b 100644
--- a/tests/baselines/reference/erasableSyntaxOnlyDeclaration.symbols
+++ b/tests/baselines/reference/erasableSyntaxOnlyDeclaration.symbols
@@ -112,3 +112,11 @@ declare function foo(): void;
 export = foo;
 >foo : Symbol(foo, Decl(other.d.cts, 0, 0))
 
+
+=== esm.d.mts ===
+declare const foo = 1234;
+>foo : Symbol(foo, Decl(esm.d.mts, 0, 13))
+
+export default foo;
+>foo : Symbol(foo, Decl(esm.d.mts, 0, 13))
+
diff --git a/tests/baselines/reference/erasableSyntaxOnlyDeclaration.types b/tests/baselines/reference/erasableSyntaxOnlyDeclaration.types
index 031eb9bbb59cb..053aa1b60d2e4 100644
--- a/tests/baselines/reference/erasableSyntaxOnlyDeclaration.types
+++ b/tests/baselines/reference/erasableSyntaxOnlyDeclaration.types
@@ -154,3 +154,15 @@ export = foo;
 >foo : () => void
 >    : ^^^^^^    
 
+
+=== esm.d.mts ===
+declare const foo = 1234;
+>foo : 1234
+>    : ^^^^
+>1234 : 1234
+>     : ^^^^
+
+export default foo;
+>foo : 1234
+>    : ^^^^
+
diff --git a/tests/cases/compiler/erasableSyntaxOnly.ts b/tests/cases/compiler/erasableSyntaxOnly.ts
index 6a76e80337e11..d2ff6d72ce8f3 100644
--- a/tests/cases/compiler/erasableSyntaxOnly.ts
+++ b/tests/cases/compiler/erasableSyntaxOnly.ts
@@ -74,3 +74,8 @@ export = foo;
 // @filename: other.d.cts
 declare function foo(): void;
 export = foo;
+
+
+// @filename: esm.mts
+const foo = 1234;
+export default foo;
diff --git a/tests/cases/compiler/erasableSyntaxOnlyDeclaration.ts b/tests/cases/compiler/erasableSyntaxOnlyDeclaration.ts
index f87e2346f094b..3a986719a160c 100644
--- a/tests/cases/compiler/erasableSyntaxOnlyDeclaration.ts
+++ b/tests/cases/compiler/erasableSyntaxOnlyDeclaration.ts
@@ -66,3 +66,8 @@ export = foo;
 // @filename: other.d.cts
 declare function foo(): void;
 export = foo;
+
+
+// @filename: esm.d.mts
+declare const foo = 1234;
+export default foo;