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Disable -Wweak-vtables when there are no key functions

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Our -Wweak-vtables diagnostic is powered by our key function
calculation, which checks if key functions are enabled. We won't find
any key functions in C++ ABIs that lack key functions, so -Wweak-vtables
was warning on every dynamic class before this change. So, turn off this
warning in ABIs without key functions.

Addresses PR31220

llvm-svn: 288850
This commit is contained in:
Reid Kleckner 2016-12-06 21:44:41 +00:00
parent 00cfa74715
commit b792e0694b
2 changed files with 21 additions and 14 deletions
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30
clang/lib/Sema/SemaDeclCXX.cpp
View File

@ -14281,6 +14281,8 @@ bool Sema::DefineUsedVTables() {
CXXRecordDecl *Class = VTableUses[I].first->getDefinition();
if (!Class)
continue;
TemplateSpecializationKind ClassTSK =
Class->getTemplateSpecializationKind();
SourceLocation Loc = VTableUses[I].second;
@ -14304,9 +14306,8 @@ bool Sema::DefineUsedVTables() {
// of an explicit instantiation declaration, suppress the
// vtable; it will live with the explicit instantiation
// definition.
bool IsExplicitInstantiationDeclaration
= Class->getTemplateSpecializationKind()
== TSK_ExplicitInstantiationDeclaration;
bool IsExplicitInstantiationDeclaration =
ClassTSK == TSK_ExplicitInstantiationDeclaration;
for (auto R : Class->redecls()) {
TemplateSpecializationKind TSK
= cast<CXXRecordDecl>(R)->getTemplateSpecializationKind();
@ -14339,17 +14340,20 @@ bool Sema::DefineUsedVTables() {
if (VTablesUsed[Canonical])
Consumer.HandleVTable(Class);
// Optionally warn if we're emitting a weak vtable.
if (Class->isExternallyVisible() &&
Class->getTemplateSpecializationKind() != TSK_ImplicitInstantiation) {
// Warn if we're emitting a weak vtable. The vtable will be weak if there is
// no key function or the key function is inlined. Don't warn in C++ ABIs
// that lack key functions, since the user won't be able to make one.
if (Context.getTargetInfo().getCXXABI().hasKeyFunctions() &&
Class->isExternallyVisible() && ClassTSK != TSK_ImplicitInstantiation) {
const FunctionDecl *KeyFunctionDef = nullptr;
if (!KeyFunction ||
(KeyFunction->hasBody(KeyFunctionDef) &&
KeyFunctionDef->isInlined()))
Diag(Class->getLocation(), Class->getTemplateSpecializationKind() ==
TSK_ExplicitInstantiationDefinition
? diag::warn_weak_template_vtable : diag::warn_weak_vtable)
<< Class;
if (!KeyFunction || (KeyFunction->hasBody(KeyFunctionDef) &&
KeyFunctionDef->isInlined())) {
Diag(Class->getLocation(),
ClassTSK == TSK_ExplicitInstantiationDefinition
? diag::warn_weak_template_vtable
: diag::warn_weak_vtable)
<< Class;
}
}
}
VTableUses.clear();

5
clang/test/SemaCXX/warn-weak-vtables.cpp
View File

@ -1,5 +1,8 @@
// RUN: %clang_cc1 %s -fsyntax-only -verify -triple %itanium_abi_triple -Wweak-vtables -Wweak-template-vtables
// RUN: %clang_cc1 %s -fsyntax-only -triple %ms_abi_triple -Werror -Wno-weak-vtables -Wno-weak-template-vtables
//
// Check that this warning is disabled on MS ABI targets which don't have key
// functions.
// RUN: %clang_cc1 %s -fsyntax-only -triple %ms_abi_triple -Werror -Wweak-vtables -Wweak-template-vtables
struct A { // expected-warning {{'A' has no out-of-line virtual method definitions; its vtable will be emitted in every translation unit}}
virtual void f() { }