[PATCH] D65511: Delay emitting dllexport explicitly defaulted members until the class is fully parsed (PR40006)

[Hans Wennborg via Phabricator via cfe-commits]

hans created this revision.
hans added reviewers: rnk, rsmith.

This is similar to r245139, but that only addressed dllexported classes. It was still possible to run into the same problem with dllexported members in an otherwise normal class (see bug). This uses the same strategy to fix: delay defining the method until the whole class has been parsed.

(The easiest way to see the ordering problem is in Parser::ParseCXXMemberSpecification(): it calls ParseLexedMemberInitializers() *after* ActOnFinishCXXMemberDecls(), which was trying to define the dllexport method. Now we delay it to ActOnFinishCXXNonNestedClass() which is called after both of those.)


https://reviews.llvm.org/D65511

Files:
  clang/include/clang/Sema/Sema.h
  clang/lib/Sema/Sema.cpp
  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
@@ -851,6 +851,15 @@
 // Baz's operator=, causing instantiation of Foo<int> after which
 // ActOnFinishCXXNonNestedClass is called, and we would bite our own tail.
 // M32-DAG: define weak_odr dso_local dllexport x86_thiscallcc dereferenceable(1) %"struct.InClassInits::Baz"* @"??4Baz at InClassInits@@QAEAAU01 at ABU01@@Z"
+
+// Trying to define the explicitly defaulted ctor must be delayed until the
+// in-class initializer for x has been processed.
+struct PR40006 {
+  __declspec(dllexport) PR40006() = default;
+  int x = 42;
+};
+// M32-DAG: define weak_odr dso_local dllexport x86_thiscallcc %"struct.InClassInits::PR40006"* @"??0PR40006 at InClassInits@@QAE at XZ"
+
 }
 
 // We had an issue where instantiating A would force emission of B's delayed
Index: clang/lib/Sema/SemaDeclCXX.cpp
===================================================================
--- clang/lib/Sema/SemaDeclCXX.cpp
+++ clang/lib/Sema/SemaDeclCXX.cpp
@@ -6283,8 +6283,8 @@
         M->dropAttr<DLLExportAttr>();
 
       if (M->hasAttr<DLLExportAttr>()) {
-        DefineImplicitSpecialMember(*this, M, M->getLocation());
-        ActOnFinishInlineFunctionDef(M);
+        // Define after any fields with in-class initializers have been parsed.
+        DelayedDllExportMemberFunctions.push_back(M);
       }
     }
   };
@@ -11537,6 +11537,15 @@
 
 void Sema::ActOnFinishCXXNonNestedClass(Decl *D) {
   referenceDLLExportedClassMethods();
+
+  if (!DelayedDllExportMemberFunctions.empty()) {
+    SmallVector<CXXMethodDecl*, 4> WorkList;
+    std::swap(DelayedDllExportMemberFunctions, WorkList);
+    for (CXXMethodDecl *M : WorkList) {
+      DefineImplicitSpecialMember(*this, M, M->getLocation());
+      ActOnFinishInlineFunctionDef(M);
+    }
+  }
 }
 
 void Sema::referenceDLLExportedClassMethods() {
Index: clang/lib/Sema/Sema.cpp
===================================================================
--- clang/lib/Sema/Sema.cpp
+++ clang/lib/Sema/Sema.cpp
@@ -961,6 +961,7 @@
 
   // All dllexport classes should have been processed already.
   assert(DelayedDllExportClasses.empty());
+  assert(DelayedDllExportMemberFunctions.empty());
 
   // Remove file scoped decls that turned out to be used.
   UnusedFileScopedDecls.erase(
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -11136,6 +11136,7 @@
   // Emitting members of dllexported classes is delayed until the class
   // (including field initializers) is fully parsed.
   SmallVector<CXXRecordDecl*, 4> DelayedDllExportClasses;
+  SmallVector<CXXMethodDecl*, 4> DelayedDllExportMemberFunctions;
 
 private:
   class SavePendingParsedClassStateRAII {


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