[PATCH] D120397: [C++20] [Modules] Make the linkage consistent for template and its specialization

[Chuanqi Xu via Phabricator via cfe-commits]

ChuanqiXu updated this revision to Diff 412886.
ChuanqiXu added a comment.

Address comments:

- File an issue and add a reference to it.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D120397/new/

https://reviews.llvm.org/D120397

Files:
  clang/lib/AST/Decl.cpp
  clang/test/CodeGenCXX/inconsistent-export-template.cpp
  clang/test/Modules/inconsist-export-template.cpp


Index: clang/test/Modules/inconsist-export-template.cpp
===================================================================
--- /dev/null
+++ clang/test/Modules/inconsist-export-template.cpp
@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -std=c++20 %s -fsyntax-only -verify
+// expected-no-diagnostics
+export module m;
+export template <class T>
+void f() {
+}
+
+template <>
+void f<int>() {
+}
+
+template <class T>
+void f1() {
+}
+
+// FIXME: We should reject following specialization,
+// since it tries to export a name which is already introduced.
+// See https://llvm.org/PR54189 for details.
+export template <>
+void f1<int>() {
+}
+
+export template <class T>
+class C {
+};
+
+template <>
+class C<int> {
+public:
+  void M(){};
+};
+
+void Use(C<int> &p) { p.M(); }
Index: clang/test/CodeGenCXX/inconsistent-export-template.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/inconsistent-export-template.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -std=c++20 %s -S -emit-llvm -triple %itanium_abi_triple 
-disable-llvm-passes -o - | FileCheck %s
+
+export module m;
+export template <class T>
+void f() {
+}
+
+// CHECK: void @_Z1fIiEvv
+template <>
+void f<int>() {
+}
Index: clang/lib/AST/Decl.cpp
===================================================================
--- clang/lib/AST/Decl.cpp
+++ clang/lib/AST/Decl.cpp
@@ -391,11 +391,18 @@
   bool considerVisibility =
     shouldConsiderTemplateVisibility(fn, specInfo);
 
-  // Merge information from the template parameters.
   FunctionTemplateDecl *temp = specInfo->getTemplate();
-  LinkageInfo tempLV =
-    getLVForTemplateParameterList(temp->getTemplateParameters(), computation);
-  LV.mergeMaybeWithVisibility(tempLV, considerVisibility);
+
+  // Merge information from the template declaration.
+  LinkageInfo tempLV = getLVForDecl(temp, computation);
+  // The linkage of the specialization should be consistent with the
+  // template declaration.
+  LV.setLinkage(tempLV.getLinkage());
+
+  // Merge information from the template parameters.
+  LinkageInfo paramsLV =
+      getLVForTemplateParameterList(temp->getTemplateParameters(), 
computation);
+  LV.mergeMaybeWithVisibility(paramsLV, considerVisibility);
 
   // Merge information from the template arguments.
   const TemplateArgumentList &templateArgs = *specInfo->TemplateArguments;



Index: clang/test/Modules/inconsist-export-template.cpp
===================================================================
--- /dev/null
+++ clang/test/Modules/inconsist-export-template.cpp
@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -std=c++20 %s -fsyntax-only -verify
+// expected-no-diagnostics
+export module m;
+export template <class T>
+void f() {
+}
+
+template <>
+void f<int>() {
+}
+
+template <class T>
+void f1() {
+}
+
+// FIXME: We should reject following specialization,
+// since it tries to export a name which is already introduced.
+// See https://llvm.org/PR54189 for details.
+export template <>
+void f1<int>() {
+}
+
+export template <class T>
+class C {
+};
+
+template <>
+class C<int> {
+public:
+  void M(){};
+};
+
+void Use(C<int> &p) { p.M(); }
Index: clang/test/CodeGenCXX/inconsistent-export-template.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/inconsistent-export-template.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -std=c++20 %s -S -emit-llvm -triple %itanium_abi_triple -disable-llvm-passes -o - | FileCheck %s
+
+export module m;
+export template <class T>
+void f() {
+}
+
+// CHECK: void @_Z1fIiEvv
+template <>
+void f<int>() {
+}
Index: clang/lib/AST/Decl.cpp
===================================================================
--- clang/lib/AST/Decl.cpp
+++ clang/lib/AST/Decl.cpp
@@ -391,11 +391,18 @@
   bool considerVisibility =
     shouldConsiderTemplateVisibility(fn, specInfo);
 
-  // Merge information from the template parameters.
   FunctionTemplateDecl *temp = specInfo->getTemplate();
-  LinkageInfo tempLV =
-    getLVForTemplateParameterList(temp->getTemplateParameters(), computation);
-  LV.mergeMaybeWithVisibility(tempLV, considerVisibility);
+
+  // Merge information from the template declaration.
+  LinkageInfo tempLV = getLVForDecl(temp, computation);
+  // The linkage of the specialization should be consistent with the
+  // template declaration.
+  LV.setLinkage(tempLV.getLinkage());
+
+  // Merge information from the template parameters.
+  LinkageInfo paramsLV =
+      getLVForTemplateParameterList(temp->getTemplateParameters(), computation);
+  LV.mergeMaybeWithVisibility(paramsLV, considerVisibility);
 
   // Merge information from the template arguments.
   const TemplateArgumentList &templateArgs = *specInfo->TemplateArguments;

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