[PATCH] D90849: [dllexport] Avoid multiple codegen assert for explicitly defaulted methods in explicit instantiation definitions (PR47683)

[Hans Wennborg via Phabricator via cfe-commits]

hans created this revision.
hans added a reviewer: rnk.
Herald added a project: clang.
hans requested review of this revision.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D90849

Files:
  clang/lib/Sema/SemaDeclCXX.cpp
  clang/test/CodeGenCXX/dllexport.cpp


Index: clang/test/CodeGenCXX/dllexport.cpp
===================================================================
--- clang/test/CodeGenCXX/dllexport.cpp
+++ clang/test/CodeGenCXX/dllexport.cpp
@@ -915,6 +915,26 @@
 // M32-DAG: define dso_local x86_thiscallcc void @"??$baz at H@?$ExportedClassTemplate2 at H@pr34849@@QAEXXZ"
 }
 
+namespace pr47683 {
+struct X { X() {} };
+
+template <typename> struct S {
+  S() = default;
+  X x;
+};
+template struct __declspec(dllexport) S<int>;
+// M32-DAG: define weak_odr dso_local dllexport x86_thiscallcc %"struct.pr47683::S"* @"??0?$S at H@pr47683@@QAE at XZ"
+
+template <typename> struct T {
+  T() = default;
+  X x;
+};
+extern template struct T<int>;
+template struct __declspec(dllexport) T<int>;
+// Don't assert about multiple codegen for explicitly defaulted method in explicit instantiation def.
+// M32-DAG: define weak_odr dso_local dllexport x86_thiscallcc %"struct.pr47683::T"* @"??0?$T at H@pr47683@@QAE at XZ"
+}
+
 //===----------------------------------------------------------------------===//
 // Classes with template base classes
 //===----------------------------------------------------------------------===//
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -5904,9 +5904,14 @@
         // an operator can be taken and should compare equal across libraries.
         S.MarkFunctionReferenced(Class->getLocation(), MD);
 
-        // There is no later point when we will see the definition of this
-        // function, so pass it to the consumer now.
-        S.Consumer.HandleTopLevelDecl(DeclGroupRef(MD));
+        if (MD->isExplicitlyDefaulted() &&
+            TSK == TSK_ExplicitInstantiationDefinition) {
+          // MD will get passed to the consumer as part of instantiation.
+        } else {
+          // There is no later point when we will see the definition of this
+          // function, so pass it to the consumer now.
+          S.Consumer.HandleTopLevelDecl(DeclGroupRef(MD));
+        }
       }
     }
   }


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