[MS] Instantiate default args during instantiation of exported default ctors

Summary:
Replace some old code that probably pre-dated the change to delay
emission of dllexported code until after the closing brace of the
outermost record type. Only uninstantiated default argument expressions
need to be handled now. It is enough to instantiate default argument
expressions when instantiating dllexported default ctors. This also
fixes some double-diagnostic issues in this area.

Fixes PR31500

Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D28274

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@291045 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 21 insertions, 54 deletions

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 084bd4c45e..a650621b57 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -5395,6 +5395,26 @@ static void ReferenceDllExportedMethods(Sema &S, CXXRecordDecl *Class) {
   }
 }
 
+static void checkForMultipleExportedDefaultConstructors(Sema &S, CXXRecordDecl *Class) {
+  CXXConstructorDecl *LastExportedDefaultCtor = nullptr;
+  for (Decl *Member : Class->decls()) {
+    // Look for exported default constructors.
+    auto *CD = dyn_cast<CXXConstructorDecl>(Member);
+    if (!CD || !CD->isDefaultConstructor() || !CD->hasAttr<DLLExportAttr>())
+      continue;
+
+    if (LastExportedDefaultCtor) {
+      S.Diag(LastExportedDefaultCtor->getLocation(),
+             diag::err_attribute_dll_ambiguous_default_ctor)
+          << Class;
+      S.Diag(CD->getLocation(), diag::note_entity_declared_at)
+          << CD->getDeclName();
+      return;
+    }
+    LastExportedDefaultCtor = CD;
+  }
+}
+
 /// \brief Check class-level dllimport/dllexport attribute.
 void Sema::checkClassLevelDLLAttribute(CXXRecordDecl *Class) {
   Attr *ClassAttr = getDLLAttr(Class);
@@ -10362,64 +10382,11 @@ void Sema::ActOnFinishCXXMemberDecls() {
       DelayedExceptionSpecChecks.clear();
       return;
     }
-  }
-}
-
-static void checkDefaultArgExprsForConstructors(Sema &S, CXXRecordDecl *Class) {
-  // Don't do anything for template patterns.
-  if (Class->getDescribedClassTemplate())
-    return;
-
-  CallingConv ExpectedCallingConv = S.Context.getDefaultCallingConvention(
-      /*IsVariadic=*/false, /*IsCXXMethod=*/true);
-
-  CXXConstructorDecl *LastExportedDefaultCtor = nullptr;
-  for (Decl *Member : Class->decls()) {
-    auto *CD = dyn_cast<CXXConstructorDecl>(Member);
-    if (!CD) {
-      // Recurse on nested classes.
-      if (auto *NestedRD = dyn_cast<CXXRecordDecl>(Member))
-        checkDefaultArgExprsForConstructors(S, NestedRD);
-      continue;
-    } else if (!CD->isDefaultConstructor() || !CD->hasAttr<DLLExportAttr>()) {
-      continue;
-    }
-
-    CallingConv ActualCallingConv =
-        CD->getType()->getAs<FunctionProtoType>()->getCallConv();
-
-    // Skip default constructors with typical calling conventions and no default
-    // arguments.
-    unsigned NumParams = CD->getNumParams();
-    if (ExpectedCallingConv == ActualCallingConv && NumParams == 0)
-      continue;
-
-    if (LastExportedDefaultCtor) {
-      S.Diag(LastExportedDefaultCtor->getLocation(),
-             diag::err_attribute_dll_ambiguous_default_ctor) << Class;
-      S.Diag(CD->getLocation(), diag::note_entity_declared_at)
-          << CD->getDeclName();
-      return;
-    }
-    LastExportedDefaultCtor = CD;
-
-    for (unsigned I = 0; I != NumParams; ++I) {
-      (void)S.CheckCXXDefaultArgExpr(Class->getLocation(), CD,
-                                     CD->getParamDecl(I));
-      S.DiscardCleanupsInEvaluationContext();
-    }
+    checkForMultipleExportedDefaultConstructors(*this, Record);
   }
 }
 
 void Sema::ActOnFinishCXXNonNestedClass(Decl *D) {
-  auto *RD = dyn_cast<CXXRecordDecl>(D);
-
-  // Default constructors that are annotated with __declspec(dllexport) which
-  // have default arguments or don't use the standard calling convention are
-  // wrapped with a thunk called the default constructor closure.
-  if (RD && Context.getTargetInfo().getCXXABI().isMicrosoft())
-    checkDefaultArgExprsForConstructors(*this, RD);
-
   referenceDLLExportedClassMethods();
 }