From f022b8d4c7fc06bdc8ecb1977f5cfb00fc72bc3f Mon Sep 17 00:00:00 2001
From: "Matthew \"strager\" Glazar" <strager.nds@gmail.com>
Date: Fri, 13 Oct 2023 21:58:08 -0400
Subject: [PATCH] fix(typescript): allow namespace and interface/type with same
 name

---
 docs/CHANGELOG.md                             |  2 ++
 src/quick-lint-js/fe/variable-analyzer.cpp    |  4 ++++
 ...ariable-analyzer-multiple-declarations.cpp | 21 +++++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index a524b1a0f5..7a67c9bc30 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -49,6 +49,8 @@ Semantic Versioning.
   * `<T>(T: T) => {}` (a generic arrow function with the same name for a
     run-time parameter and a generic parameter) no longer falsely reports
     [E0034][] ("redeclaration of variable").
+  * A namespace with the same name as an interface or type alias no longer
+    falsely reports [E0034][] ("redeclaration of variable").
   * Nested `module` declarations no longer falsely report [E0361][]. E0361's
     message has been changed:
     * Before: "module with string name is only allowed at the top level"
diff --git a/src/quick-lint-js/fe/variable-analyzer.cpp b/src/quick-lint-js/fe/variable-analyzer.cpp
index 7b3cdfcf06..26daf699a9 100644
--- a/src/quick-lint-js/fe/variable-analyzer.cpp
+++ b/src/quick-lint-js/fe/variable-analyzer.cpp
@@ -1053,6 +1053,7 @@ void Variable_Analyzer::report_error_if_variable_declaration_conflicts(
       (kind == VK::_interface          && other_kind == VK::_class) ||
       (kind == VK::_interface          && other_kind == VK::_import) ||
       (kind == VK::_interface          && other_kind == VK::_interface) ||
+      (kind == VK::_interface          && other_kind == VK::_namespace) ||
       (kind == VK::_interface          && !is_type(other_kind)) ||
       (kind == VK::_let                && other_kind == VK::_namespace) ||
       (kind == VK::_let                && other_kind == VK::_type_alias) ||
@@ -1060,11 +1061,14 @@ void Variable_Analyzer::report_error_if_variable_declaration_conflicts(
       (kind == VK::_namespace          && other_kind == VK::_const) ||
       (kind == VK::_namespace          && other_kind == VK::_enum) ||
       (kind == VK::_namespace          && other_kind == VK::_function) ||
+      (kind == VK::_namespace          && other_kind == VK::_interface) ||
       (kind == VK::_namespace          && other_kind == VK::_let) ||
       (kind == VK::_namespace          && other_kind == VK::_namespace) ||
+      (kind == VK::_namespace          && other_kind == VK::_type_alias) ||
       (kind == VK::_namespace          && other_kind == VK::_var) ||
       (kind == VK::_type_alias         && other_kind == VK::_const) ||
       (kind == VK::_type_alias         && other_kind == VK::_let) ||
+      (kind == VK::_type_alias         && other_kind == VK::_namespace) ||
       (kind == VK::_type_alias         && other_kind == VK::_var) ||
       (kind == VK::_var                && other_kind == VK::_catch) ||
       (kind == VK::_var                && other_kind == VK::_function) ||
diff --git a/test/test-variable-analyzer-multiple-declarations.cpp b/test/test-variable-analyzer-multiple-declarations.cpp
index f7eeeafc9e..1f01be20a8 100644
--- a/test/test-variable-analyzer-multiple-declarations.cpp
+++ b/test/test-variable-analyzer-multiple-declarations.cpp
@@ -49,6 +49,27 @@ TEST(Test_Variable_Analyzer_Multiple_Declarations,
                          typescript_analyze_options, default_globals);
 }
 
+TEST(Test_Variable_Analyzer_Multiple_Declarations,
+     type_or_interface_does_not_conflict_with_namespace) {
+  test_parse_and_analyze(u8"namespace n {}   type n = null;"_sv, no_diags,
+                         typescript_analyze_options, default_globals);
+  test_parse_and_analyze(u8"namespace n {;}  type n = null;"_sv, no_diags,
+                         typescript_analyze_options, default_globals);
+  test_parse_and_analyze(u8"type n = null;   namespace n {}"_sv, no_diags,
+                         typescript_analyze_options, default_globals);
+  test_parse_and_analyze(u8"type n = null;   namespace n {;}"_sv, no_diags,
+                         typescript_analyze_options, default_globals);
+
+  test_parse_and_analyze(u8"namespace n {}   interface n {}"_sv, no_diags,
+                         typescript_analyze_options, default_globals);
+  test_parse_and_analyze(u8"namespace n {;}  interface n {}"_sv, no_diags,
+                         typescript_analyze_options, default_globals);
+  test_parse_and_analyze(u8"interface n {}   namespace n {}"_sv, no_diags,
+                         typescript_analyze_options, default_globals);
+  test_parse_and_analyze(u8"interface n {}   namespace n {;}"_sv, no_diags,
+                         typescript_analyze_options, default_globals);
+}
+
 TEST(Test_Variable_Analyzer_Multiple_Declarations,
      namespace_can_be_declared_multiple_times) {
   test_parse_and_analyze(