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PR35697: look at the first declaration when determining whether a function or 

variable is extern "C" in linkage calculations.

llvm-svn: 321686
This commit is contained in:
Richard Smith 2018-01-03 02:34:35 +00:00
parent dd74d83f84
commit 99f54799d1
2 changed files with 20 additions and 3 deletions
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6
clang/lib/AST/Decl.cpp
View File

@ -779,7 +779,7 @@ LinkageComputer::getLVForNamespaceScopeDecl(const NamedDecl *D,
// unique-external linkage, it's not legally usable from outside
// this translation unit. However, we should use the C linkage
// rules instead for extern "C" declarations.
if (Context.getLangOpts().CPlusPlus && !Function->isInExternCContext()) {
if (Context.getLangOpts().CPlusPlus && !isFirstInExternCContext(Function)) {
// Only look at the type-as-written. Otherwise, deducing the return type
// of a function could change its linkage.
QualType TypeAsWritten = Function->getType();
@ -1165,7 +1165,7 @@ LinkageInfo LinkageComputer::getLVForLocalDecl(const NamedDecl *D,
LVComputationKind computation) {
if (const auto *Function = dyn_cast<FunctionDecl>(D)) {
if (Function->isInAnonymousNamespace() &&
!Function->isInExternCContext())
!isFirstInExternCContext(Function))
return getInternalLinkageFor(Function);
// This is a "void f();" which got merged with a file static.
@ -1188,7 +1188,7 @@ LinkageInfo LinkageComputer::getLVForLocalDecl(const NamedDecl *D,
if (const auto *Var = dyn_cast<VarDecl>(D)) {
if (Var->hasExternalStorage()) {
if (Var->isInAnonymousNamespace() && !Var->isInExternCContext())
if (Var->isInAnonymousNamespace() && !isFirstInExternCContext(Var))
return getInternalLinkageFor(Var);
LinkageInfo LV;

17
clang/test/SemaCXX/extern-c.cpp
View File

@ -242,3 +242,20 @@ namespace tag_hiding {
ExternCStruct3 *q3 = p3;
ExternCStruct4 *q4 = p4; // expected-error {{ambiguous}}
}
namespace PR35697 {
typedef struct {} *ReturnStruct;
extern "C" ReturnStruct PR35697_f();
extern "C" ReturnStruct PR35697_v;
ReturnStruct PR35697_f();
ReturnStruct PR35697_v;
namespace {
extern "C" ReturnStruct PR35697_f();
extern "C" ReturnStruct PR35697_v;
void q() {
extern ReturnStruct PR35697_f();
extern ReturnStruct PR35697_v;
}
}
}