When name lookup comes across a declaration that is in a module that

is not visible, look for any previous declarations of that entity that
might be visible.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146563 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 63 insertions, 20 deletions

diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index 9f1e9a5516..a6ad8f8fcf 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -321,6 +321,12 @@ void LookupResult::deletePaths(CXXBasePaths *Paths) {
   delete Paths;
 }
 
+static NamedDecl *getVisibleDecl(NamedDecl *D);
+
+NamedDecl *LookupResult::getAcceptableDeclSlow(NamedDecl *D) const {
+  return getVisibleDecl(D);
+}
+
 /// Resolves the result kind of this lookup.
 void LookupResult::resolveKind() {
   unsigned N = Decls.size();
@@ -649,7 +655,7 @@ static bool LookupDirect(Sema &S, LookupResult &R, const DeclContext *DC) {
   DeclContext::lookup_const_iterator I, E;
   for (llvm::tie(I, E) = DC->lookup(R.getLookupName()); I != E; ++I) {
     NamedDecl *D = *I;
-    if (R.isAcceptableDecl(D)) {
+    if ((D = R.getAcceptableDecl(D))) {
       R.addDecl(D);
       Found = true;
     }
@@ -875,9 +881,9 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
     // Check whether the IdResolver has anything in this scope.
     bool Found = false;
     for (; I != IEnd && S->isDeclScope(*I); ++I) {
-      if (R.isAcceptableDecl(*I)) {
+      if (NamedDecl *ND = R.getAcceptableDecl(*I)) {
         Found = true;
-        R.addDecl(*I);
+        R.addDecl(ND);
       }
     }
     if (Found) {
@@ -926,8 +932,8 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
                 if (ObjCIvarDecl *Ivar = Class->lookupInstanceVariable(
                                                  Name.getAsIdentifierInfo(),
                                                              ClassDeclared)) {
-                  if (R.isAcceptableDecl(Ivar)) {
-                    R.addDecl(Ivar);
+                  if (NamedDecl *ND = R.getAcceptableDecl(Ivar)) {
+                    R.addDecl(ND);
                     R.resolveKind();
                     return true;
                   }
@@ -977,13 +983,13 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
     // Check whether the IdResolver has anything in this scope.
     bool Found = false;
     for (; I != IEnd && S->isDeclScope(*I); ++I) {
-      if (R.isAcceptableDecl(*I)) {
+      if (NamedDecl *ND = R.getAcceptableDecl(*I)) {
         // We found something.  Look for anything else in our scope
         // with this same name and in an acceptable identifier
         // namespace, so that we can construct an overload set if we
         // need to.
         Found = true;
-        R.addDecl(*I);
+        R.addDecl(ND);
       }
     }
 
@@ -1047,6 +1053,40 @@ bool Sema::CppLookupName(LookupResult &R, Scope *S) {
   return !R.empty();
 }
 
+/// \brief Retrieve the previous declaration of D.
+static NamedDecl *getPreviousDeclaration(NamedDecl *D) {
+  if (TagDecl *TD = dyn_cast<TagDecl>(D))
+    return TD->getPreviousDeclaration();
+  if (VarDecl *VD = dyn_cast<VarDecl>(D))
+    return VD->getPreviousDeclaration();
+  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
+    return FD->getPreviousDeclaration();
+  if (RedeclarableTemplateDecl *RTD = dyn_cast<RedeclarableTemplateDecl>(D))
+    return RTD->getPreviousDeclaration();
+  
+  return 0;
+}
+
+/// \brief Retrieve the visible declaration corresponding to D, if any.
+///
+/// This routine determines whether the declaration D is visible in the current
+/// module, with the current imports. If not, it checks whether any
+/// redeclaration of D is visible, and if so, returns that declaration.
+/// 
+/// \returns D, or a visible previous declaration of D, whichever is more recent
+/// and visible. If no declaration of D is visible, returns null.
+static NamedDecl *getVisibleDecl(NamedDecl *D) {
+  if (LookupResult::isVisible(D))
+    return D;
+  
+  while ((D = getPreviousDeclaration(D))) {
+    if (LookupResult::isVisible(D))
+      return D;
+  }
+  
+  return 0;
+}
+
 /// @brief Perform unqualified name lookup starting from a given
 /// scope.
 ///
@@ -1125,10 +1165,11 @@ bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation) {
         
         // If this declaration is module-private and it came from an AST
         // file, we can't see it.
-        if ((*I)->isModulePrivate() && (*I)->isFromASTFile())
+        NamedDecl *D = getVisibleDecl(*I);
+        if (!D)
           continue;
-            
-        R.addDecl(*I);
+                
+        R.addDecl(D);
 
         if ((*I)->getAttr<OverloadableAttr>()) {
           // If this declaration has the "overloadable" attribute, we
@@ -1145,7 +1186,10 @@ bool Sema::LookupName(LookupResult &R, Scope *S, bool AllowBuiltinCreation) {
           for (++LastI; LastI != IEnd; ++LastI) {
             if (!S->isDeclScope(*LastI))
               break;
-            R.addDecl(*LastI);
+            
+            D = getVisibleDecl(*LastI);
+            if (D)
+              R.addDecl(D);
           }
         }
 
@@ -2712,7 +2756,7 @@ static void LookupVisibleDecls(DeclContext *Ctx, LookupResult &Result,
                                  DEnd = CurCtx->decls_end();
          D != DEnd; ++D) {
       if (NamedDecl *ND = dyn_cast<NamedDecl>(*D)) {
-        if (Result.isAcceptableDecl(ND)) {
+        if ((ND = Result.getAcceptableDecl(ND))) {
           Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
           Visited.add(ND);
         }
@@ -2723,17 +2767,16 @@ static void LookupVisibleDecls(DeclContext *Ctx, LookupResult &Result,
                PEnd = ForwardProto->protocol_end();
              P != PEnd;
              ++P) {
-          if (Result.isAcceptableDecl(*P)) {
-            Consumer.FoundDecl(*P, Visited.checkHidden(*P), Ctx, InBaseClass);
-            Visited.add(*P);
+          if (NamedDecl *ND = Result.getAcceptableDecl(*P)) {
+            Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
+            Visited.add(ND);
           }
         }
       } else if (ObjCClassDecl *Class = dyn_cast<ObjCClassDecl>(*D)) {
           ObjCInterfaceDecl *IFace = Class->getForwardInterfaceDecl();
-          if (Result.isAcceptableDecl(IFace)) {
-            Consumer.FoundDecl(IFace, Visited.checkHidden(IFace), Ctx,
-                               InBaseClass);
-            Visited.add(IFace);
+          if (NamedDecl *ND = Result.getAcceptableDecl(IFace)) {
+            Consumer.FoundDecl(ND, Visited.checkHidden(ND), Ctx, InBaseClass);
+            Visited.add(ND);
           }
       }
       
@@ -2873,7 +2916,7 @@ static void LookupVisibleDecls(Scope *S, LookupResult &Result,
     for (Scope::decl_iterator D = S->decl_begin(), DEnd = S->decl_end();
          D != DEnd; ++D) {
       if (NamedDecl *ND = dyn_cast<NamedDecl>(*D))
-        if (Result.isAcceptableDecl(ND)) {
+        if ((ND = Result.getAcceptableDecl(ND))) {
           Consumer.FoundDecl(ND, Visited.checkHidden(ND), 0, false);
           Visited.add(ND);
         }