PR33552: Distinguish between declarations that are owned by no module and

declarations that are owned but unconditionally visible.

This allows us to set declarations as visible even if they have a local owning
module, without losing information. In turn, that means that our Objective-C
support can keep on incorrectly assuming the "hidden" bit on the declaration is
the whole story with regard to name visibility. This will also be useful once
we support the C++ Modules TS export semantics.

Objective-C name visibility is still incorrect in any case where the "hidden"
bit is not the complete story: for instance, in Objective-C++ the set of
visible categories will be wrong during template instantiation, and with local
submodule visibility enabled it will be wrong when building modules. Fixing that
will require a major overhaul of how visibility is handled for Objective-C (and
particularly for categories).

llvm-svn: 306075

5 files changed, 14 insertions, 10 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 2f78d06a82d..b94b8d9e4c1 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16104,7 +16104,10 @@ void Sema::ActOnModuleBegin(SourceLocation DirectiveLoc, Module *Mod) {
   // lexically within the module.
   if (getLangOpts().trackLocalOwningModule()) {
     for (auto *DC = CurContext; DC; DC = DC->getLexicalParent()) {
-      cast<Decl>(DC)->setHidden(true);
+      cast<Decl>(DC)->setModuleOwnershipKind(
+          getLangOpts().ModulesLocalVisibility
+              ? Decl::ModuleOwnershipKind::VisibleWhenImported
+              : Decl::ModuleOwnershipKind::Visible);
       cast<Decl>(DC)->setLocalOwningModule(Mod);
     }
   }
@@ -16144,7 +16147,8 @@ void Sema::ActOnModuleEnd(SourceLocation EomLoc, Module *Mod) {
     for (auto *DC = CurContext; DC; DC = DC->getLexicalParent()) {
       cast<Decl>(DC)->setLocalOwningModule(getCurrentModule());
       if (!getCurrentModule())
-        cast<Decl>(DC)->setHidden(false);
+        cast<Decl>(DC)->setModuleOwnershipKind(
+            Decl::ModuleOwnershipKind::Unowned);
     }
   }
 }
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index a9ff21bc41a..710ead30790 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -2630,7 +2630,7 @@ void Sema::DeclareGlobalAllocationFunction(DeclarationName Name,
           // Make the function visible to name lookup, even if we found it in
           // an unimported module. It either is an implicitly-declared global
           // allocation function, or is suppressing that function.
-          Func->setHidden(false);
+          Func->setVisibleDespiteOwningModule();
           return;
         }
       }
@@ -2662,7 +2662,7 @@ void Sema::DeclareGlobalAllocationFunction(DeclarationName Name,
         FnType, /*TInfo=*/nullptr, SC_None, false, true);
     Alloc->setImplicit();
     // Global allocation functions should always be visible.
-    Alloc->setHidden(false);
+    Alloc->setVisibleDespiteOwningModule();
 
     // Implicit sized deallocation functions always have default visibility.
     Alloc->addAttr(
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 9f657a446c0..2e7fb875a27 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -1341,7 +1341,7 @@ void Sema::makeMergedDefinitionVisible(NamedDecl *ND) {
     Context.mergeDefinitionIntoModule(ND, M);
   else
     // We're not building a module; just make the definition visible.
-    ND->setHidden(false);
+    ND->setVisibleDespiteOwningModule();
 
   // If ND is a template declaration, make the template parameters
   // visible too. They're not (necessarily) within a mergeable DeclContext.
@@ -1528,7 +1528,7 @@ bool LookupResult::isVisibleSlow(Sema &SemaRef, NamedDecl *D) {
           !SemaRef.getLangOpts().ModulesLocalVisibility) {
         // Cache the fact that this declaration is implicitly visible because
         // its parent has a visible definition.
-        D->setHidden(false);
+        D->setVisibleDespiteOwningModule();
       }
       return true;
     }
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index fe92dd8ac65..f4f0c804aee 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2045,7 +2045,7 @@ Sema::InstantiateClass(SourceLocation PointOfInstantiation,
 
   // The instantiation is visible here, even if it was first declared in an
   // unimported module.
-  Instantiation->setHidden(false);
+  Instantiation->setVisibleDespiteOwningModule();
 
   // FIXME: This loses the as-written tag kind for an explicit instantiation.
   Instantiation->setTagKind(Pattern->getTagKind());
@@ -2247,7 +2247,7 @@ bool Sema::InstantiateEnum(SourceLocation PointOfInstantiation,
 
   // The instantiation is visible here, even if it was first declared in an
   // unimported module.
-  Instantiation->setHidden(false);
+  Instantiation->setVisibleDespiteOwningModule();
 
   // Enter the scope of this instantiation. We don't use
   // PushDeclContext because we don't have a scope.
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 578386fc113..abe912fb548 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3868,7 +3868,7 @@ void Sema::InstantiateFunctionDefinition(SourceLocation PointOfInstantiation,
 
   // The instantiation is visible here, even if it was first declared in an
   // unimported module.
-  Function->setHidden(false);
+  Function->setVisibleDespiteOwningModule();
 
   // Copy the inner loc start from the pattern.
   Function->setInnerLocStart(PatternDecl->getInnerLocStart());
@@ -4274,7 +4274,7 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
 
       // The instantiation is visible here, even if it was first declared in an
       // unimported module.
-      Var->setHidden(false);
+      Var->setVisibleDespiteOwningModule();
 
       // If we're performing recursive template instantiation, create our own
       // queue of pending implicit instantiations that we will instantiate