From 6d9b84797c1c4bd00a2392043e9feea4ecebe482 Mon Sep 17 00:00:00 2001
From: Chuanqi Xu <yedeng.yd@linux.alibaba.com>
Date: Fri, 22 Jul 2022 17:03:38 +0800
Subject: [PATCH] [C++20] [Modules] Handle reachability for partial
 specialization

Previously we don't catch the reachability for partial specialization.
Handle them in this patch.
---
 clang/lib/Sema/SemaTemplate.cpp               |  4 +--
 .../test/Modules/partial_specialization.cppm  | 34 +++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)
 create mode 100644 clang/test/Modules/partial_specialization.cppm

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 171f005816b5..95c83ebfaeab 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -4573,7 +4573,7 @@ Sema::CheckVarTemplateId(VarTemplateDecl *Template, SourceLocation TemplateLoc,
   void *InsertPos = nullptr;
   if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
           Converted, InsertPos)) {
-    checkSpecializationVisibility(TemplateNameLoc, Spec);
+    checkSpecializationReachability(TemplateNameLoc, Spec);
     // If we already have a variable template specialization, return it.
     return Spec;
   }
@@ -4694,7 +4694,7 @@ Sema::CheckVarTemplateId(VarTemplateDecl *Template, SourceLocation TemplateLoc,
           dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
     Decl->setInstantiationOf(D, InstantiationArgs);
 
-  checkSpecializationVisibility(TemplateNameLoc, Decl);
+  checkSpecializationReachability(TemplateNameLoc, Decl);
 
   assert(Decl && "No variable template specialization?");
   return Decl;
diff --git a/clang/test/Modules/partial_specialization.cppm b/clang/test/Modules/partial_specialization.cppm
new file mode 100644
index 000000000000..3a0185717211
--- /dev/null
+++ b/clang/test/Modules/partial_specialization.cppm
@@ -0,0 +1,34 @@
+// RUN: rm -rf %t
+// RUN: split-file %s %t
+// RUN: cd %t
+//
+// RUN: %clang_cc1 -std=c++20 -emit-module-interface %t/A.cppm -o %t/A.pcm
+// RUN: %clang_cc1 -std=c++20 -fprebuilt-module-path=%t %t/Use.cpp -fsyntax-only -verify
+//
+//--- foo.h
+template<typename T, typename U>
+inline constexpr bool IsSame = false;
+
+template<typename T>
+inline constexpr bool IsSame<T, T> = true;
+
+template <typename T>
+class A {
+public:
+    A();
+    ~A() noexcept(IsSame<T, T>);
+};
+
+//--- A.cppm
+module;
+#include "foo.h"
+export module A;
+export using ::A;
+
+//--- Use.cpp
+import A;
+void bool_consume(bool b);
+void use() {
+    A<int> a{};
+    bool_consume(IsSame); // expected-error {{use of undeclared identifier 'IsSame'}}
+}