[modules] Switch from inferring owning modules based on source location to

inferring based on the current module at the point of creation.

This should result in no functional change except when building a preprocessed
module (or more generally when using #pragma clang module begin/end to switch
module in the middle of a file), in which case it allows us to correctly track
the owning module for declarations. We can't map from FileID to module in the
preprocessed module case, since all modules would have the same FileID.

There are still a couple of remaining places that try to infer a module from a
source location; I'll clean those up in follow-up changes.

llvm-svn: 303322

1 files changed, 60 insertions, 44 deletions

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 04350831c68..66c10093d9e 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -1420,11 +1420,46 @@ bool Sema::hasVisibleDefaultArgument(const NamedDecl *D,
                                      Modules);
 }
 
+template<typename Filter>
+static bool hasVisibleDeclarationImpl(Sema &S, const NamedDecl *D,
+                                      llvm::SmallVectorImpl<Module *> *Modules,
+                                      Filter F) {
+  for (auto *Redecl : D->redecls()) {
+    auto *R = cast<NamedDecl>(Redecl);
+    if (!F(R))
+      continue;
+
+    if (S.isVisible(R))
+      return true;
+
+    if (Modules) {
+      Modules->push_back(R->getOwningModule());
+      const auto &Merged = S.Context.getModulesWithMergedDefinition(R);
+      Modules->insert(Modules->end(), Merged.begin(), Merged.end());
+    }
+  }
+
+  return false;
+}
+
+bool Sema::hasVisibleExplicitSpecialization(
+    const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
+  return hasVisibleDeclarationImpl(*this, D, Modules, [](const NamedDecl *D) {
+    if (auto *RD = dyn_cast<CXXRecordDecl>(D))
+      return RD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization;
+    if (auto *FD = dyn_cast<FunctionDecl>(D))
+      return FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization;
+    if (auto *VD = dyn_cast<VarDecl>(D))
+      return VD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization;
+    llvm_unreachable("unknown explicit specialization kind");
+  });
+}
+
 bool Sema::hasVisibleMemberSpecialization(
     const NamedDecl *D, llvm::SmallVectorImpl<Module *> *Modules) {
   assert(isa<CXXRecordDecl>(D->getDeclContext()) &&
          "not a member specialization");
-  for (auto *Redecl : D->redecls()) {
+  return hasVisibleDeclarationImpl(*this, D, Modules, [](const NamedDecl *D) {
     // If the specialization is declared at namespace scope, then it's a member
     // specialization declaration. If it's lexically inside the class
     // definition then it was instantiated.
@@ -1432,19 +1467,8 @@ bool Sema::hasVisibleMemberSpecialization(
     // FIXME: This is a hack. There should be a better way to determine this.
     // FIXME: What about MS-style explicit specializations declared within a
     //        class definition?
-    if (Redecl->getLexicalDeclContext()->isFileContext()) {
-      auto *NonConstR = const_cast<NamedDecl*>(cast<NamedDecl>(Redecl));
-
-      if (isVisible(NonConstR))
-        return true;
-
-      if (Modules) {
-        Modules->push_back(getOwningModule(NonConstR));
-        const auto &Merged = Context.getModulesWithMergedDefinition(NonConstR);
-        Modules->insert(Modules->end(), Merged.begin(), Merged.end());
-      }
-    }
-  }
+    return D->getLexicalDeclContext()->isFileContext();
+  });
 
   return false;
 }
@@ -1459,23 +1483,19 @@ bool Sema::hasVisibleMemberSpecialization(
 /// your module can see, including those later on in your module).
 bool LookupResult::isVisibleSlow(Sema &SemaRef, NamedDecl *D) {
   assert(D->isHidden() && "should not call this: not in slow case");
-  Module *DeclModule = nullptr;
-  
-  if (SemaRef.getLangOpts().ModulesLocalVisibility) {
-    DeclModule = SemaRef.getOwningModule(D);
-    if (!DeclModule) {
-      assert(!D->isHidden() && "hidden decl not from a module");
-      return true;
-    }
 
-    // If the owning module is visible, and the decl is not module private,
-    // then the decl is visible too. (Module private is ignored within the same
-    // top-level module.)
-    if ((!D->isFromASTFile() || !D->isModulePrivate()) &&
-        (SemaRef.isModuleVisible(DeclModule) ||
-         SemaRef.hasVisibleMergedDefinition(D)))
-      return true;
-  }
+  Module *DeclModule = SemaRef.getOwningModule(D);
+  assert(DeclModule && "hidden decl not from a module");
+
+  // If the owning module is visible, and the decl is not module private,
+  // then the decl is visible too. (Module private is ignored within the same
+  // top-level module.)
+  // FIXME: Check the owning module for module-private declarations rather than
+  // assuming "same AST file" is the same thing as "same module".
+  if ((!D->isFromASTFile() || !D->isModulePrivate()) &&
+      (SemaRef.isModuleVisible(DeclModule) ||
+       SemaRef.hasVisibleMergedDefinition(D)))
+    return true;
 
   // If this declaration is not at namespace scope nor module-private,
   // then it is visible if its lexical parent has a visible definition.
@@ -1571,20 +1591,8 @@ static NamedDecl *findAcceptableDecl(Sema &SemaRef, NamedDecl *D) {
 bool Sema::hasVisibleDeclarationSlow(const NamedDecl *D,
                                      llvm::SmallVectorImpl<Module *> *Modules) {
   assert(!isVisible(D) && "not in slow case");
-
-  for (auto *Redecl : D->redecls()) {
-    auto *NonConstR = const_cast<NamedDecl*>(cast<NamedDecl>(Redecl));
-    if (isVisible(NonConstR))
-      return true;
-
-    if (Modules) {
-      Modules->push_back(getOwningModule(NonConstR));
-      const auto &Merged = Context.getModulesWithMergedDefinition(NonConstR);
-      Modules->insert(Modules->end(), Merged.begin(), Merged.end());
-    }
-  }
-
-  return false;
+  return hasVisibleDeclarationImpl(*this, D, Modules,
+                                   [](const NamedDecl *) { return true; });
 }
 
 NamedDecl *LookupResult::getAcceptableDeclSlow(NamedDecl *D) const {
@@ -4957,6 +4965,14 @@ void Sema::diagnoseMissingImport(SourceLocation UseLoc, NamedDecl *Decl,
                                  MissingImportKind MIK, bool Recover) {
   assert(!Modules.empty());
 
+  // Weed out duplicates from module list.
+  llvm::SmallVector<Module*, 8> UniqueModules;
+  llvm::SmallDenseSet<Module*, 8> UniqueModuleSet;
+  for (auto *M : Modules)
+    if (UniqueModuleSet.insert(M).second)
+      UniqueModules.push_back(M);
+  Modules = UniqueModules;
+
   if (Modules.size() > 1) {
     std::string ModuleList;
     unsigned N = 0;