Revert r185229 as it breaks compilation of <windows.h>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@185256 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 9f9bf1e..a87cf61 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -4359,14 +4359,10 @@
/// function-scope declarations.
void
Sema::RegisterLocallyScopedExternCDecl(NamedDecl *ND, Scope *S) {
- if (!getLangOpts().CPlusPlus &&
- ND->getLexicalDeclContext()->getRedeclContext()->isTranslationUnit())
- // Don't need to track declarations in the TU in C.
- return;
-
+ assert(
+ !ND->getLexicalDeclContext()->getRedeclContext()->isTranslationUnit() &&
+ "Decl is not a locally-scoped decl!");
// Note that we have a locally-scoped external with this name.
- // FIXME: There can be multiple such declarations if they are functions marked
- // __attribute__((overloadable)) declared in function scope in C.
LocallyScopedExternCDecls[ND->getDeclName()] = ND;
}
@@ -4685,32 +4681,6 @@
return isC99Inline;
}
-/// Determine whether a variable is extern "C" prior to attaching
-/// an initializer. We can't just call isExternC() here, because that
-/// will also compute and cache whether the declaration is externally
-/// visible, which might change when we attach the initializer.
-///
-/// This can only be used if the declaration is known to not be a
-/// redeclaration of an internal linkage declaration.
-///
-/// For instance:
-///
-/// auto x = []{};
-///
-/// Attaching the initializer here makes this declaration not externally
-/// visible, because its type has internal linkage.
-///
-/// FIXME: This is a hack.
-template<typename T>
-static bool isIncompleteDeclExternC(Sema &S, const T *D) {
- if (S.getLangOpts().CPlusPlus) {
- // In C++, the overloadable attribute negates the effects of extern "C".
- if (!D->isInExternCContext() || D->template hasAttr<OverloadableAttr>())
- return false;
- }
- return D->isExternC();
-}
-
static bool shouldConsiderLinkage(const VarDecl *VD) {
const DeclContext *DC = VD->getDeclContext()->getRedeclContext();
if (DC->isFunctionOrMethod())
@@ -5100,10 +5070,16 @@
ProcessPragmaWeak(S, NewVD);
checkAttributesAfterMerging(*this, *NewVD);
- // If this is the first declaration of an extern C variable, update
- // the map of such variables.
- if (!NewVD->getPreviousDecl() && !NewVD->isInvalidDecl() &&
- isIncompleteDeclExternC(*this, NewVD))
+ // If this is the first declaration of an extern C variable that is not
+ // declared directly in the translation unit, update the map of such
+ // variables.
+ if (!CurContext->getRedeclContext()->isTranslationUnit() &&
+ !NewVD->getPreviousDecl() && !NewVD->isInvalidDecl() &&
+ // FIXME: We only check isExternC if we're in an extern C context,
+ // to avoid computing and caching an 'externally visible' flag which
+ // could change if the variable's type is not visible.
+ (!getLangOpts().CPlusPlus || NewVD->isInExternCContext()) &&
+ NewVD->isExternC())
RegisterLocallyScopedExternCDecl(NewVD, S);
return NewVD;
@@ -5204,120 +5180,30 @@
CheckShadow(S, D, R);
}
-/// Check for conflict between this global or extern "C" declaration and
-/// previous global or extern "C" declarations. This is only used in C++.
template<typename T>
-static bool checkGlobalOrExternCConflict(
- Sema &S, const T *ND, bool IsGlobal, LookupResult &Previous) {
- assert(S.getLangOpts().CPlusPlus && "only C++ has extern \"C\"");
- NamedDecl *Prev = S.findLocallyScopedExternCDecl(ND->getDeclName());
+static bool mayConflictWithNonVisibleExternC(const T *ND) {
+ const DeclContext *DC = ND->getDeclContext();
+ if (DC->getRedeclContext()->isTranslationUnit())
+ return true;
- if (!Prev && IsGlobal && !isIncompleteDeclExternC(S, ND)) {
- // The common case: this global doesn't conflict with any extern "C"
- // declaration.
- return false;
- }
-
- if (Prev) {
- if (!IsGlobal || isIncompleteDeclExternC(S, ND)) {
- // Both the old and new declarations have C language linkage. This is a
- // redeclaration.
- Previous.clear();
- Previous.addDecl(Prev);
- return true;
- }
-
- // This is a global, non-extern "C" declaration, and there is a previous
- // non-global extern "C" declaration. Diagnose.
- } else {
- // The declaration is extern "C". Check for any declaration in the
- // translation unit which might conflict.
- if (IsGlobal) {
- // We have already performed the lookup into the translation unit.
- IsGlobal = false;
- for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
- I != E; ++I) {
- if (isa<VarDecl>(*I) || isa<FunctionDecl>(*I)) {
- Prev = *I;
- break;
- }
- }
- } else {
- DeclContext::lookup_result R =
- S.Context.getTranslationUnitDecl()->lookup(ND->getDeclName());
- for (DeclContext::lookup_result::iterator I = R.begin(), E = R.end();
- I != E; ++I) {
- if (isa<VarDecl>(*I) || isa<FunctionDecl>(*I)) {
- Prev = *I;
- break;
- }
- // FIXME: If we have any other entity with this name in global scope,
- // the declaration is ill-formed, but that is a defect: it breaks the
- // 'stat' hack, for instance.
- }
- }
-
- if (!Prev)
+ // We know that is the first decl we see, other than function local
+ // extern C ones. If this is C++ and the decl is not in a extern C context
+ // it cannot have C language linkage. Avoid calling isExternC in that case.
+ // We need to this because of code like
+ //
+ // namespace { struct bar {}; }
+ // auto foo = bar();
+ //
+ // This code runs before the init of foo is set, and therefore before
+ // the type of foo is known. Not knowing the type we cannot know its linkage
+ // unless it is in an extern C block.
+ if (!ND->isInExternCContext()) {
+ const ASTContext &Context = ND->getASTContext();
+ if (Context.getLangOpts().CPlusPlus)
return false;
}
- // Use the first declaration's location to ensure we point at something which
- // is lexically inside an extern "C" linkage-spec.
- assert(Prev && "should have found a previous declaration to diagnose");
- if (FunctionDecl *FD = dyn_cast<FunctionDecl>(Prev))
- Prev = FD->getFirstDeclaration();
- else
- Prev = cast<VarDecl>(Prev)->getFirstDeclaration();
-
- S.Diag(ND->getLocation(), diag::err_extern_c_global_conflict)
- << IsGlobal << ND;
- S.Diag(Prev->getLocation(), diag::note_extern_c_global_conflict)
- << IsGlobal;
- return false;
-}
-
-/// Apply special rules for handling extern "C" declarations. Returns \c true
-/// if we have found that this is a redeclaration of some prior entity.
-///
-/// Per C++ [dcl.link]p6:
-/// Two declarations [for a function or variable] with C language linkage
-/// with the same name that appear in different scopes refer to the same
-/// [entity]. An entity with C language linkage shall not be declared with
-/// the same name as an entity in global scope.
-template<typename T>
-static bool checkForConflictWithNonVisibleExternC(Sema &S, const T *ND,
- LookupResult &Previous) {
- if (!S.getLangOpts().CPlusPlus) {
- // In C, when declaring a global variable, look for a corresponding 'extern'
- // variable declared in function scope.
- //
- // FIXME: The corresponding case in C++ does not work. We should instead
- // set the semantic DC for an extern local variable to be the innermost
- // enclosing namespace, and ensure they are only found by redeclaration
- // lookup.
- if (ND->getDeclContext()->getRedeclContext()->isTranslationUnit()) {
- if (NamedDecl *Prev = S.findLocallyScopedExternCDecl(ND->getDeclName())) {
- Previous.clear();
- Previous.addDecl(Prev);
- return true;
- }
- }
- return false;
- }
-
- // A declaration in the translation unit can conflict with an extern "C"
- // declaration.
- if (ND->getDeclContext()->getRedeclContext()->isTranslationUnit())
- return checkGlobalOrExternCConflict(S, ND, /*IsGlobal*/true, Previous);
-
- // An extern "C" declaration can conflict with a declaration in the
- // translation unit or can be a redeclaration of an extern "C" declaration
- // in another scope.
- if (isIncompleteDeclExternC(S,ND))
- return checkGlobalOrExternCConflict(S, ND, /*IsGlobal*/false, Previous);
-
- // Neither global nor extern "C": nothing to do.
- return false;
+ return ND->isExternC();
}
void Sema::CheckVariableDeclarationType(VarDecl *NewVD) {
@@ -5500,9 +5386,14 @@
// The most important point here is that we're not allowed to
// update our understanding of the type according to declarations
// not in scope.
- bool PreviousWasHidden =
- Previous.empty() &&
- checkForConflictWithNonVisibleExternC(*this, NewVD, Previous);
+ bool PreviousWasHidden = false;
+ if (Previous.empty() && mayConflictWithNonVisibleExternC(NewVD)) {
+ if (NamedDecl *ExternCPrev =
+ findLocallyScopedExternCDecl(NewVD->getDeclName())) {
+ Previous.addDecl(ExternCPrev);
+ PreviousWasHidden = true;
+ }
+ }
// Filter out any non-conflicting previous declarations.
filterNonConflictingPreviousDecls(Context, NewVD, Previous);
@@ -6734,10 +6625,12 @@
// marking the function.
AddCFAuditedAttribute(NewFD);
- // If this is the first declaration of an extern C variable, update
- // the map of such variables.
- if (!NewFD->getPreviousDecl() && !NewFD->isInvalidDecl() &&
- isIncompleteDeclExternC(*this, NewFD))
+ // If this is the first declaration of an extern C variable that is not
+ // declared directly in the translation unit, update the map of such
+ // variables.
+ if (!CurContext->getRedeclContext()->isTranslationUnit() &&
+ !NewFD->getPreviousDecl() && NewFD->isExternC() &&
+ !NewFD->isInvalidDecl())
RegisterLocallyScopedExternCDecl(NewFD, S);
// Set this FunctionDecl's range up to the right paren.
@@ -6841,6 +6734,15 @@
assert(!NewFD->getResultType()->isVariablyModifiedType()
&& "Variably modified return types are not handled here");
+ // Check for a previous declaration of this name.
+ if (Previous.empty() && mayConflictWithNonVisibleExternC(NewFD)) {
+ // Since we did not find anything by this name, look for a non-visible
+ // extern "C" declaration with the same name.
+ if (NamedDecl *ExternCPrev =
+ findLocallyScopedExternCDecl(NewFD->getDeclName()))
+ Previous.addDecl(ExternCPrev);
+ }
+
// Filter out any non-conflicting previous declarations.
filterNonConflictingPreviousDecls(Context, NewFD, Previous);
@@ -6895,34 +6797,6 @@
}
}
- // Check for a previous extern "C" declaration with this name.
- if (!Redeclaration &&
- checkForConflictWithNonVisibleExternC(*this, NewFD, Previous)) {
- filterNonConflictingPreviousDecls(Context, NewFD, Previous);
- if (!Previous.empty()) {
- // This is an extern "C" declaration with the same name as a previous
- // declaration, and thus redeclares that entity...
- Redeclaration = true;
- OldDecl = Previous.getFoundDecl();
-
- // ... except in the presence of __attribute__((overloadable)).
- if (OldDecl->hasAttr<OverloadableAttr>()) {
- if (!getLangOpts().CPlusPlus && !NewFD->hasAttr<OverloadableAttr>()) {
- Diag(NewFD->getLocation(), diag::err_attribute_overloadable_missing)
- << Redeclaration << NewFD;
- Diag(Previous.getFoundDecl()->getLocation(),
- diag::note_attribute_overloadable_prev_overload);
- NewFD->addAttr(::new (Context) OverloadableAttr(SourceLocation(),
- Context));
- }
- if (IsOverload(NewFD, cast<FunctionDecl>(OldDecl), false)) {
- Redeclaration = false;
- OldDecl = 0;
- }
- }
- }
- }
-
// C++11 [dcl.constexpr]p8:
// A constexpr specifier for a non-static member function that is not
// a constructor declares that member function to be const.