Revert "Reinstate r281429, reverted in r281452, with a fix for its mishandling of"

This reverts commit r284176. It still marks some modules as invisible
that should be visible. Will follow up with the author with a test case.

llvm-svn: 284382

13 files changed, 23 insertions, 129 deletions

diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
index f5a9bd2da54..3d777524b83 100644
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -308,18 +308,10 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// merged into.
   llvm::DenseMap<Decl*, Decl*> MergedDecls;
 
-  /// The modules into which a definition has been merged, or a map from a
-  /// merged definition to its canonical definition. This is really a union of
-  /// a NamedDecl* and a vector of Module*.
-  struct MergedModulesOrCanonicalDef {
-    llvm::TinyPtrVector<Module*> MergedModules;
-    NamedDecl *CanonicalDef = nullptr;
-  };
-
   /// \brief A mapping from a defining declaration to a list of modules (other
   /// than the owning module of the declaration) that contain merged
   /// definitions of that entity.
-  llvm::DenseMap<NamedDecl*, MergedModulesOrCanonicalDef> MergedDefModules;
+  llvm::DenseMap<NamedDecl*, llvm::TinyPtrVector<Module*>> MergedDefModules;
 
   /// \brief Initializers for a module, in order. Each Decl will be either
   /// something that has a semantic effect on startup (such as a variable with
@@ -891,7 +883,6 @@ public:
   /// and should be visible whenever \p M is visible.
   void mergeDefinitionIntoModule(NamedDecl *ND, Module *M,
                                  bool NotifyListeners = true);
-  void mergeDefinitionIntoModulesOf(NamedDecl *ND, NamedDecl *Other);
   /// \brief Clean up the merged definition list. Call this if you might have
   /// added duplicates into the list.
   void deduplicateMergedDefinitonsFor(NamedDecl *ND);
@@ -902,9 +893,7 @@ public:
     auto MergedIt = MergedDefModules.find(Def);
     if (MergedIt == MergedDefModules.end())
       return None;
-    if (auto *CanonDef = MergedIt->second.CanonicalDef)
-      return getModulesWithMergedDefinition(CanonDef);
-    return MergedIt->second.MergedModules;
+    return MergedIt->second;
   }
 
   /// Add a declaration to the list of declarations that are initialized
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 34eced3f4b1..3da1c74bc12 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -888,74 +888,18 @@ void ASTContext::mergeDefinitionIntoModule(NamedDecl *ND, Module *M,
     if (auto *Listener = getASTMutationListener())
       Listener->RedefinedHiddenDefinition(ND, M);
 
-  auto *Merged = &MergedDefModules[ND];
-  if (auto *CanonDef = Merged->CanonicalDef) {
-    ND = CanonDef;
-    Merged = &MergedDefModules[ND];
-  }
-  assert(!Merged->CanonicalDef && "canonical def not canonical");
-
-  Merged->MergedModules.push_back(M);
-
-  if (!getLangOpts().ModulesLocalVisibility)
+  if (getLangOpts().ModulesLocalVisibility)
+    MergedDefModules[ND].push_back(M);
+  else
     ND->setHidden(false);
 }
 
-void ASTContext::mergeDefinitionIntoModulesOf(NamedDecl *Def,
-                                              NamedDecl *Other) {
-  // We need to know the owning module of the merge source.
-  assert(Other->isFromASTFile() && "merge of non-imported decl not supported");
-  assert(Def != Other && "merging definition into itself");
-
-  if (!Other->isHidden()) {
-    Def->setHidden(false);
-    return;
-  }
-
-  assert(Other->getImportedOwningModule() &&
-         "hidden, imported declaration has no owning module");
-
-  // Mark Def as the canonical definition of merged definition Other.
-  {
-    auto &OtherMerged = MergedDefModules[Other];
-    assert((!OtherMerged.CanonicalDef || OtherMerged.CanonicalDef == Def) &&
-           "mismatched canonical definitions for declaration");
-    OtherMerged.CanonicalDef = Def;
-  }
-
-  auto &Merged = MergedDefModules[Def];
-  // Grab this again, we potentially just invalidated our reference.
-  auto &OtherMerged = MergedDefModules[Other];
-
-  if (Module *M = Other->getImportedOwningModule())
-    Merged.MergedModules.push_back(M);
-
-  // If this definition had any others merged into it, they're now merged into
-  // the canonical definition instead.
-  if (!OtherMerged.MergedModules.empty()) {
-    assert(!Merged.CanonicalDef && "canonical definition not canonical");
-    if (Merged.MergedModules.empty())
-      Merged.MergedModules = std::move(OtherMerged.MergedModules);
-    else
-      Merged.MergedModules.insert(Merged.MergedModules.end(),
-                                  OtherMerged.MergedModules.begin(),
-                                  OtherMerged.MergedModules.end());
-    OtherMerged.MergedModules.clear();
-  }
-}
-
 void ASTContext::deduplicateMergedDefinitonsFor(NamedDecl *ND) {
   auto It = MergedDefModules.find(ND);
   if (It == MergedDefModules.end())
     return;
 
-  if (auto *CanonDef = It->second.CanonicalDef) {
-    It = MergedDefModules.find(CanonDef);
-    if (It == MergedDefModules.end())
-      return;
-  }
-
-  auto &Merged = It->second.MergedModules;
+  auto &Merged = It->second;
   llvm::DenseSet<Module*> Found;
   for (Module *&M : Merged)
     if (!Found.insert(M).second)
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index ac136e95b4e..8ce118ce710 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3481,10 +3481,23 @@ void ASTReader::makeModuleVisible(Module *Mod,
 /// visible.
 void ASTReader::mergeDefinitionVisibility(NamedDecl *Def,
                                           NamedDecl *MergedDef) {
+  // FIXME: This doesn't correctly handle the case where MergedDef is visible
+  // in modules other than its owning module. We should instead give the
+  // ASTContext a list of merged definitions for Def.
   if (Def->isHidden()) {
     // If MergedDef is visible or becomes visible, make the definition visible.
-    getContext().mergeDefinitionIntoModulesOf(Def, MergedDef);
-    PendingMergedDefinitionsToDeduplicate.insert(Def);
+    if (!MergedDef->isHidden())
+      Def->Hidden = false;
+    else if (getContext().getLangOpts().ModulesLocalVisibility) {
+      getContext().mergeDefinitionIntoModule(
+          Def, MergedDef->getImportedOwningModule(),
+          /*NotifyListeners*/ false);
+      PendingMergedDefinitionsToDeduplicate.insert(Def);
+    } else {
+      auto SubmoduleID = MergedDef->getOwningModuleID();
+      assert(SubmoduleID && "hidden definition in no module");
+      HiddenNamesMap[getSubmodule(SubmoduleID)].push_back(Def);
+    }
   }
 }
 
@@ -8619,7 +8632,7 @@ void ASTReader::finishPendingActions() {
       const FunctionDecl *Defn = nullptr;
       if (!getContext().getLangOpts().Modules || !FD->hasBody(Defn))
         FD->setLazyBody(PB->second);
-      else if (FD != Defn)
+      else
         mergeDefinitionVisibility(const_cast<FunctionDecl*>(Defn), FD);
       continue;
     }
diff --git a/clang/test/Modules/Inputs/merge-template-pattern-visibility/a.h b/clang/test/Modules/Inputs/merge-template-pattern-visibility/a.h
index b960ba6f573..e6592027611 100644
--- a/clang/test/Modules/Inputs/merge-template-pattern-visibility/a.h
+++ b/clang/test/Modules/Inputs/merge-template-pattern-visibility/a.h
@@ -4,8 +4,3 @@ template<typename T> struct B;
 template<typename, typename> struct A {};
 template<typename T> struct B : A<T> {};
 template<typename T> inline auto C(T) {}
-
-namespace CrossModuleMerge {
-  template<typename T> inline auto D(T) {}
-  struct E {};
-}
diff --git a/clang/test/Modules/Inputs/merge-template-pattern-visibility/b.h b/clang/test/Modules/Inputs/merge-template-pattern-visibility/b.h
index 260b6b318ef..41b52d5e6ab 100644
--- a/clang/test/Modules/Inputs/merge-template-pattern-visibility/b.h
+++ b/clang/test/Modules/Inputs/merge-template-pattern-visibility/b.h
@@ -17,7 +17,4 @@ namespace CrossModuleMerge {
   template<typename, typename> struct A {};
   template<typename T> struct B : A<T> {};
   template<typename T> inline auto C(T) {}
-
-  template<typename T> inline auto D(T) {}
-  struct E;
 }
diff --git a/clang/test/Modules/Inputs/merge-template-pattern-visibility/c.h b/clang/test/Modules/Inputs/merge-template-pattern-visibility/c.h
index 01594bb4b89..db80eda1ea6 100644
--- a/clang/test/Modules/Inputs/merge-template-pattern-visibility/c.h
+++ b/clang/test/Modules/Inputs/merge-template-pattern-visibility/c.h
@@ -5,8 +5,5 @@ namespace CrossModuleMerge {
   template<typename, typename> struct A {};
   template<typename T> struct B : A<T> {};
   template<typename T> inline auto C(T) {}
-
-  template<typename T> inline auto D(T) {}
-  struct E {};
 }
 
diff --git a/clang/test/Modules/Inputs/merge-template-pattern-visibility/d.h b/clang/test/Modules/Inputs/merge-template-pattern-visibility/d.h
index 7bbd01ebce4..464f0f5bbed 100644
--- a/clang/test/Modules/Inputs/merge-template-pattern-visibility/d.h
+++ b/clang/test/Modules/Inputs/merge-template-pattern-visibility/d.h
@@ -1,3 +1 @@
-namespace CrossModuleMerge {
-  struct E {};
-}
+// d.h: empty
diff --git a/clang/test/Modules/Inputs/merge-var-template-def/a.h b/clang/test/Modules/Inputs/merge-var-template-def/a.h
deleted file mode 100644
index cce887530d7..00000000000
--- a/clang/test/Modules/Inputs/merge-var-template-def/a.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef A_H
-#define A_H
-template<typename T> struct A { static bool b; };
-template<typename T> bool A<T>::b = false;
-template<typename T> void *get() { return &(A<T>::b); }
-#endif
diff --git a/clang/test/Modules/Inputs/merge-var-template-def/b1.h b/clang/test/Modules/Inputs/merge-var-template-def/b1.h
deleted file mode 100644
index 1ef89746f72..00000000000
--- a/clang/test/Modules/Inputs/merge-var-template-def/b1.h
+++ /dev/null
@@ -1,7 +0,0 @@
-#ifndef B1_H
-#define B1_H
-template<typename T> struct A { static bool b; };
-template<typename T> bool A<T>::b = false;
-template<typename T> void *get() { return &(A<T>::b); }
-#include "a.h"
-#endif
diff --git a/clang/test/Modules/Inputs/merge-var-template-def/b2.h b/clang/test/Modules/Inputs/merge-var-template-def/b2.h
deleted file mode 100644
index 3c7e5303e65..00000000000
--- a/clang/test/Modules/Inputs/merge-var-template-def/b2.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#ifndef B2_H
-#define B2_H
-template<typename T> struct A { static bool b; };
-template<typename T> bool A<T>::b = false;
-template<typename T> void *get() { return &(A<T>::b); }
-#endif
diff --git a/clang/test/Modules/Inputs/merge-var-template-def/module.modulemap b/clang/test/Modules/Inputs/merge-var-template-def/module.modulemap
deleted file mode 100644
index b2c96bd8217..00000000000
--- a/clang/test/Modules/Inputs/merge-var-template-def/module.modulemap
+++ /dev/null
@@ -1,5 +0,0 @@
-module a { header "a.h" export * }
-module b {
-  module b1 { header "b1.h" export * }
-  module b2 { header "b2.h" export * }
-}
diff --git a/clang/test/Modules/merge-template-pattern-visibility.cpp b/clang/test/Modules/merge-template-pattern-visibility.cpp
index bb34d3b2a60..ec5aa26c68d 100644
--- a/clang/test/Modules/merge-template-pattern-visibility.cpp
+++ b/clang/test/Modules/merge-template-pattern-visibility.cpp
@@ -7,12 +7,6 @@
 // RUN:            -fmodules-local-submodule-visibility -o %t/Y.pcm
 // RUN: %clang_cc1 -fmodules -fno-modules-error-recovery -std=c++14 -fmodule-file=%t/X.pcm -fmodule-file=%t/Y.pcm \
 // RUN:            -fmodules-local-submodule-visibility -verify %s -I%S/Inputs/merge-template-pattern-visibility
-// RUN: %clang_cc1 -fmodules -fno-modules-error-recovery -std=c++14 -fmodule-file=%t/Y.pcm -fmodule-file=%t/X.pcm \
-// RUN:            -fmodules-local-submodule-visibility -verify %s -I%S/Inputs/merge-template-pattern-visibility
-// RUN: %clang_cc1 -fmodules -fno-modules-error-recovery -std=c++14 -fmodule-file=%t/X.pcm -fmodule-file=%t/Y.pcm \
-// RUN:            -verify %s -I%S/Inputs/merge-template-pattern-visibility
-// RUN: %clang_cc1 -fmodules -fno-modules-error-recovery -std=c++14 -fmodule-file=%t/Y.pcm -fmodule-file=%t/X.pcm \
-// RUN:            -verify %s -I%S/Inputs/merge-template-pattern-visibility
 
 #include "b.h"
 #include "d.h"
@@ -21,6 +15,4 @@
 void g() {
   CrossModuleMerge::B<int> bi;
   CrossModuleMerge::C(0);
-  CrossModuleMerge::D(0);
-  CrossModuleMerge::E e;
 }
diff --git a/clang/test/Modules/merge-var-template-def.cpp b/clang/test/Modules/merge-var-template-def.cpp
deleted file mode 100644
index 4d39cad3103..00000000000
--- a/clang/test/Modules/merge-var-template-def.cpp
+++ /dev/null
@@ -1,7 +0,0 @@
-// RUN: rm -rf %t
-// RUN: %clang_cc1 -I%S/Inputs/merge-var-template-def -verify -fmodules -Werror=undefined-internal -fmodules-local-submodule-visibility -fmodules-cache-path=%t -fimplicit-module-maps %s
-// expected-no-diagnostics
-
-#include "b2.h"
-namespace { struct X; }
-void *x = get<X>();