r291453 - [MS] Mark default args of exported default constructors as used

[Reid Kleckner via cfe-commits]

Author: rnk
Date: Mon Jan  9 11:27:17 2017
New Revision: 291453

URL: http://llvm.org/viewvc/llvm-project?rev=291453&view=rev
Log:
[MS] Mark default args of exported default constructors as used

Fixes a regression introduced in r291045, which would lead to link
errors. While we should no longer encounter unparsed or uninstantiated
default arguments in this codepath, we still need to call
CheckCXXDefaultArgExpr to mark the default argument expressions as
ODR-used.

Modified:
    cfe/trunk/lib/Sema/SemaDeclCXX.cpp
    cfe/trunk/test/CodeGenCXX/dllexport-ctor-closure.cpp

Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=291453&r1=291452&r2=291453&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Mon Jan  9 11:27:17 2017
@@ -5395,14 +5395,32 @@ static void ReferenceDllExportedMethods(
   }
 }
 
-static void checkForMultipleExportedDefaultConstructors(Sema &S, CXXRecordDecl *Class) {
+static void checkForMultipleExportedDefaultConstructors(Sema &S,
+                                                        CXXRecordDecl *Class) {
+  // Only the MS ABI has default constructor closures, so we don't need to do
+  // this semantic checking anywhere else.
+  if (!S.Context.getTargetInfo().getCXXABI().isMicrosoft())
+    return;
+
   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>())
+    if (!CD || !CD->isDefaultConstructor())
+      continue;
+    auto *Attr = CD->getAttr<DLLExportAttr>();
+    if (!Attr)
       continue;
 
+    // If the class is non-dependent, mark the default arguments as ODR-used so
+    // that we can properly codegen the constructor closure.
+    if (!Class->isDependentContext()) {
+      for (ParmVarDecl *PD : CD->parameters()) {
+        (void)S.CheckCXXDefaultArgExpr(Attr->getLocation(), CD, PD);
+        S.DiscardCleanupsInEvaluationContext();
+      }
+    }
+
     if (LastExportedDefaultCtor) {
       S.Diag(LastExportedDefaultCtor->getLocation(),
              diag::err_attribute_dll_ambiguous_default_ctor)

Modified: cfe/trunk/test/CodeGenCXX/dllexport-ctor-closure.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/dllexport-ctor-closure.cpp?rev=291453&r1=291452&r2=291453&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/dllexport-ctor-closure.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/dllexport-ctor-closure.cpp Mon Jan  9 11:27:17 2017
@@ -61,3 +61,22 @@ struct __declspec(dllexport) NestedOuter
 
 // CHECK-LABEL: define weak_odr dllexport x86_thiscallcc void @"\01??_FNestedOuter@@QAEXXZ"({{.*}}) {{#[0-9]+}} comdat
 // CHECK-LABEL: define weak_odr dllexport x86_thiscallcc void @"\01??_FNestedInner at NestedOuter@@QAEXXZ"({{.*}}) {{#[0-9]+}} comdat
+
+struct HasDtor {
+  ~HasDtor();
+  int o;
+};
+struct HasImplicitDtor1 { HasDtor o; };
+struct HasImplicitDtor2 { HasDtor o; };
+struct __declspec(dllexport) CtorClosureInline {
+  CtorClosureInline(const HasImplicitDtor1 &v = {}) {}
+};
+struct __declspec(dllexport) CtorClosureOutOfLine {
+  CtorClosureOutOfLine(const HasImplicitDtor2 &v = {});
+};
+CtorClosureOutOfLine::CtorClosureOutOfLine(const HasImplicitDtor2 &v) {}
+
+// CHECK-LABEL: define weak_odr dllexport x86_thiscallcc void @"\01??_FCtorClosureInline@@QAEXXZ"
+// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01??1HasImplicitDtor1@@QAE at XZ"
+// CHECK-LABEL: define weak_odr dllexport x86_thiscallcc void @"\01??_FCtorClosureOutOfLine@@QAEXXZ"
+// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01??1HasImplicitDtor2@@QAE at XZ"