Allow a using directive to refer to the implicitly-defined namespace
"std", with a warning, to improve GCC compatibility. Fixes PR7517.
As a drive-by, add typo correction for using directives.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@107172 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index c6f149e..66d0bf5 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -3452,6 +3452,21 @@
PopDeclContext();
}
+/// \brief Retrieve the special "std" namespace, which may require us to
+/// implicitly define the namespace.
+NamespaceDecl *Sema::getStdNamespace() {
+ if (!StdNamespace) {
+ // The "std" namespace has not yet been defined, so build one implicitly.
+ StdNamespace = NamespaceDecl::Create(Context,
+ Context.getTranslationUnitDecl(),
+ SourceLocation(),
+ &PP.getIdentifierTable().get("std"));
+ StdNamespace->setImplicit(true);
+ }
+
+ return StdNamespace;
+}
+
Sema::DeclPtrTy Sema::ActOnUsingDirective(Scope *S,
SourceLocation UsingLoc,
SourceLocation NamespcLoc,
@@ -3465,13 +3480,46 @@
assert(S->getFlags() & Scope::DeclScope && "Invalid Scope.");
UsingDirectiveDecl *UDir = 0;
-
+ NestedNameSpecifier *Qualifier = 0;
+ if (SS.isSet())
+ Qualifier = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
+
// Lookup namespace name.
LookupResult R(*this, NamespcName, IdentLoc, LookupNamespaceName);
LookupParsedName(R, S, &SS);
if (R.isAmbiguous())
return DeclPtrTy();
+ if (R.empty()) {
+ // Allow "using namespace std;" or "using namespace ::std;" even if
+ // "std" hasn't been defined yet, for GCC compatibility.
+ if ((!Qualifier || Qualifier->getKind() == NestedNameSpecifier::Global) &&
+ NamespcName->isStr("std")) {
+ Diag(IdentLoc, diag::ext_using_undefined_std);
+ R.addDecl(getStdNamespace());
+ R.resolveKind();
+ }
+ // Otherwise, attempt typo correction.
+ else if (DeclarationName Corrected = CorrectTypo(R, S, &SS, 0, false,
+ CTC_NoKeywords, 0)) {
+ if (R.getAsSingle<NamespaceDecl>() ||
+ R.getAsSingle<NamespaceAliasDecl>()) {
+ if (DeclContext *DC = computeDeclContext(SS, false))
+ Diag(IdentLoc, diag::err_using_directive_member_suggest)
+ << NamespcName << DC << Corrected << SS.getRange()
+ << FixItHint::CreateReplacement(IdentLoc, Corrected.getAsString());
+ else
+ Diag(IdentLoc, diag::err_using_directive_suggest)
+ << NamespcName << Corrected
+ << FixItHint::CreateReplacement(IdentLoc, Corrected.getAsString());
+ Diag(R.getFoundDecl()->getLocation(), diag::note_namespace_defined_here)
+ << Corrected;
+
+ NamespcName = Corrected.getAsIdentifierInfo();
+ }
+ }
+ }
+
if (!R.empty()) {
NamedDecl *Named = R.getFoundDecl();
assert((isa<NamespaceDecl>(Named) || isa<NamespaceAliasDecl>(Named))