[modules] If we reach a definition of a class for which we already have a
non-visible definition, skip the new definition and make the old one visible
instead of trying to parse it again and failing horribly. C++'s ODR allows
us to assume that the two definitions are identical.
llvm-svn: 233250
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 1234afb..ffd2239 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16,6 +16,7 @@
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTLambda.h"
+#include "clang/AST/ASTMutationListener.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/CommentDiagnostic.h"
@@ -11233,13 +11234,16 @@
return FixItHint::CreateInsertion(NameLoc, Insertion);
}
-/// ActOnTag - This is invoked when we see 'struct foo' or 'struct {'. In the
+/// \brief This is invoked when we see 'struct foo' or 'struct {'. In the
/// former case, Name will be non-null. In the later case, Name will be null.
/// TagSpec indicates what kind of tag this is. TUK indicates whether this is a
/// reference/declaration/definition of a tag.
///
-/// IsTypeSpecifier is true if this is a type-specifier (or
+/// \param IsTypeSpecifier \c true if this is a type-specifier (or
/// trailing-type-specifier) other than one in an alias-declaration.
+///
+/// \param SkipBody If non-null, will be set to true if the caller should skip
+/// the definition of this tag, and treat it as if it were a declaration.
Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
SourceLocation KWLoc, CXXScopeSpec &SS,
IdentifierInfo *Name, SourceLocation NameLoc,
@@ -11250,7 +11254,7 @@
SourceLocation ScopedEnumKWLoc,
bool ScopedEnumUsesClassTag,
TypeResult UnderlyingType,
- bool IsTypeSpecifier) {
+ bool IsTypeSpecifier, bool *SkipBody) {
// If this is not a definition, it must have a name.
IdentifierInfo *OrigName = Name;
assert((Name != nullptr || TUK == TUK_Definition) &&
@@ -11676,7 +11680,7 @@
// Diagnose attempts to redefine a tag.
if (TUK == TUK_Definition) {
- if (TagDecl *Def = PrevTagDecl->getDefinition()) {
+ if (NamedDecl *Def = PrevTagDecl->getDefinition()) {
// If we're defining a specialization and the previous definition
// is from an implicit instantiation, don't emit an error
// here; we'll catch this in the general case below.
@@ -11692,7 +11696,19 @@
TSK_ExplicitSpecialization;
}
- if (!IsExplicitSpecializationAfterInstantiation) {
+ if (SkipBody && getLangOpts().CPlusPlus &&
+ !hasVisibleDefinition(Def, &Def)) {
+ // There is a definition of this tag, but it is not visible. We
+ // explicitly make use of C++'s one definition rule here, and
+ // assume that this definition is identical to the hidden one
+ // we already have. Make the existing definition visible and
+ // use it in place of this one.
+ *SkipBody = true;
+ if (auto *Listener = getASTMutationListener())
+ Listener->RedefinedHiddenDefinition(Def, KWLoc);
+ Def->setHidden(false);
+ return Def;
+ } else if (!IsExplicitSpecializationAfterInstantiation) {
// A redeclaration in function prototype scope in C isn't
// visible elsewhere, so merely issue a warning.
if (!getLangOpts().CPlusPlus && S->containedInPrototypeScope())