From 858e0e0a4236ab913b6e900aa922b94b40df68ce Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Thu, 11 May 2017 23:11:16 +0000
Subject: [PATCH] Remove unnecessary mapping from SourceLocation to Module.

When we parse a redefinition of an entity for which we have a hidden existing
declaration, make it visible in the current module instead of mapping the
current source location to its containing module.

llvm-svn: 302842
---
 clang/include/clang/Sema/Sema.h |  7 ++++++-
 clang/lib/Sema/SemaDecl.cpp     | 13 ++++++-------
 clang/lib/Sema/SemaLookup.cpp   |  6 +++---
 clang/lib/Sema/SemaTemplate.cpp |  6 +++---
 4 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 7b4ccddd7fc5..b39483ab64a9 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -1456,6 +1456,11 @@ private:
   /// The modules we're currently parsing.
   llvm::SmallVector<ModuleScope, 16> ModuleScopes;
 
+  /// Get the module whose scope we are currently within.
+  Module *getCurrentModule() const {
+    return ModuleScopes.empty() ? nullptr : ModuleScopes.back().Module;
+  }
+
   VisibleModuleSet VisibleModules;
 
   Module *CachedFakeTopLevelModule;
@@ -1466,7 +1471,7 @@ public:
 
   /// \brief Make a merged definition of an existing hidden definition \p ND
   /// visible at the specified location.
-  void makeMergedDefinitionVisible(NamedDecl *ND, SourceLocation Loc);
+  void makeMergedDefinitionVisible(NamedDecl *ND);
 
   bool isModuleVisible(Module *M) { return VisibleModules.isVisible(M); }
 
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index b7f52b8765a4..fb5f56e0523f 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2127,7 +2127,7 @@ void Sema::MergeTypedefNameDecl(Scope *S, TypedefNameDecl *New,
         New->setTypeSourceInfo(OldTD->getTypeSourceInfo());
 
       // Make the old tag definition visible.
-      makeMergedDefinitionVisible(Hidden, NewTag->getLocation());
+      makeMergedDefinitionVisible(Hidden);
 
       // If this was an unscoped enumeration, yank all of its enumerators
       // out of the scope.
@@ -3929,8 +3929,8 @@ bool Sema::checkVarDeclRedefinition(VarDecl *Old, VarDecl *New) {
 
     // Make the canonical definition visible.
     if (auto *OldTD = Old->getDescribedVarTemplate())
-      makeMergedDefinitionVisible(OldTD, New->getLocation());
-    makeMergedDefinitionVisible(Old, New->getLocation());
+      makeMergedDefinitionVisible(OldTD);
+    makeMergedDefinitionVisible(Old);
     return false;
   } else {
     Diag(New->getLocation(), diag::err_redefinition) << New;
@@ -11884,9 +11884,8 @@ Sema::CheckForFunctionRedefinition(FunctionDecl *FD,
        Definition->getNumTemplateParameterLists())) {
     SkipBody->ShouldSkip = true;
     if (auto *TD = Definition->getDescribedFunctionTemplate())
-      makeMergedDefinitionVisible(TD, FD->getLocation());
-    makeMergedDefinitionVisible(const_cast<FunctionDecl*>(Definition),
-                                FD->getLocation());
+      makeMergedDefinitionVisible(TD);
+    makeMergedDefinitionVisible(const_cast<FunctionDecl*>(Definition));
     return;
   }
 
@@ -13540,7 +13539,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
                 // we already have. Make the existing definition visible and
                 // use it in place of this one.
                 SkipBody->ShouldSkip = true;
-                makeMergedDefinitionVisible(Hidden, KWLoc);
+                makeMergedDefinitionVisible(Hidden);
                 return Def;
               } else if (!IsExplicitSpecializationAfterInstantiation) {
                 // A redeclaration in function prototype scope in C isn't
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 6a3b01798398..c5b579a4b2e9 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -1382,8 +1382,8 @@ Module *Sema::getOwningModule(Decl *Entity) {
   return M;
 }
 
-void Sema::makeMergedDefinitionVisible(NamedDecl *ND, SourceLocation Loc) {
-  if (auto *M = PP.getModuleContainingLocation(Loc))
+void Sema::makeMergedDefinitionVisible(NamedDecl *ND) {
+  if (auto *M = getCurrentModule())
     Context.mergeDefinitionIntoModule(ND, M);
   else
     // We're not building a module; just make the definition visible.
@@ -1393,7 +1393,7 @@ void Sema::makeMergedDefinitionVisible(NamedDecl *ND, SourceLocation Loc) {
   // visible too. They're not (necessarily) within a mergeable DeclContext.
   if (auto *TD = dyn_cast<TemplateDecl>(ND))
     for (auto *Param : *TD->getTemplateParameters())
-      makeMergedDefinitionVisible(Param, Loc);
+      makeMergedDefinitionVisible(Param);
 }
 
 /// \brief Find the module in which the given declaration was defined.
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 71414beb41b3..a479d1027533 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1330,8 +1330,8 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
           auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
           assert(Tmpl && "original definition of a class template is not a "
                          "class template?");
-          makeMergedDefinitionVisible(Hidden, KWLoc);
-          makeMergedDefinitionVisible(Tmpl, KWLoc);
+          makeMergedDefinitionVisible(Hidden);
+          makeMergedDefinitionVisible(Tmpl);
           return Def;
         }
 
@@ -7431,7 +7431,7 @@ Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
     NamedDecl *Hidden = nullptr;
     if (Def && SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
       SkipBody->ShouldSkip = true;
-      makeMergedDefinitionVisible(Hidden, KWLoc);
+      makeMergedDefinitionVisible(Hidden);
       // From here on out, treat this as just a redeclaration.
       TUK = TUK_Declaration;
     } else if (Def) {