vendor/clang/clang-trunk-r290819

1 files changed, 66 insertions, 28 deletions

diff --git a/lib/Tooling/Core/Lookup.cpp b/lib/Tooling/Core/Lookup.cpp
index 697eeb46ce41..6edf61b8050d 100644
--- a/lib/Tooling/Core/Lookup.cpp
+++ b/lib/Tooling/Core/Lookup.cpp
@@ -13,37 +13,69 @@
 
 #include "clang/Tooling/Core/Lookup.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
 using namespace clang;
 using namespace clang::tooling;
 
-static bool isInsideDifferentNamespaceWithSameName(const DeclContext *DeclA,
-                                                   const DeclContext *DeclB) {
-  while (true) {
-    // Look past non-namespaces on DeclA.
-    while (DeclA && !isa<NamespaceDecl>(DeclA))
-      DeclA = DeclA->getParent();
-
-    // Look past non-namespaces on DeclB.
-    while (DeclB && !isa<NamespaceDecl>(DeclB))
-      DeclB = DeclB->getParent();
-
-    // We hit the root, no namespace collision.
-    if (!DeclA || !DeclB)
-      return false;
+// Gets all namespaces that \p Context is in as a vector (ignoring anonymous
+// namespaces). The inner namespaces come before outer namespaces in the vector.
+// For example, if the context is in the following namespace:
+//    `namespace a { namespace b { namespace c ( ... ) } }`,
+// the vector will be `{c, b, a}`.
+static llvm::SmallVector<const NamespaceDecl *, 4>
+getAllNamedNamespaces(const DeclContext *Context) {
+  llvm::SmallVector<const NamespaceDecl *, 4> Namespaces;
+  auto GetNextNamedNamespace = [](const DeclContext *Context) {
+    // Look past non-namespaces and anonymous namespaces on FromContext.
+    while (Context && (!isa<NamespaceDecl>(Context) ||
+                       cast<NamespaceDecl>(Context)->isAnonymousNamespace()))
+      Context = Context->getParent();
+    return Context;
+  };
+  for (Context = GetNextNamedNamespace(Context); Context != nullptr;
+       Context = GetNextNamedNamespace(Context->getParent()))
+    Namespaces.push_back(cast<NamespaceDecl>(Context));
+  return Namespaces;
+}
 
+// Returns true if the context in which the type is used and the context in
+// which the type is declared are the same semantical namespace but different
+// lexical namespaces.
+static bool
+usingFromDifferentCanonicalNamespace(const DeclContext *FromContext,
+                                     const DeclContext *UseContext) {
+  // We can skip anonymous namespace because:
+  // 1. `FromContext` and `UseContext` must be in the same anonymous namespaces
+  // since referencing across anonymous namespaces is not possible.
+  // 2. If `FromContext` and `UseContext` are in the same anonymous namespace,
+  // the function will still return `false` as expected.
+  llvm::SmallVector<const NamespaceDecl *, 4> FromNamespaces =
+      getAllNamedNamespaces(FromContext);
+  llvm::SmallVector<const NamespaceDecl *, 4> UseNamespaces =
+      getAllNamedNamespaces(UseContext);
+  // If `UseContext` has fewer level of nested namespaces, it cannot be in the
+  // same canonical namespace as the `FromContext`.
+  if (UseNamespaces.size() < FromNamespaces.size())
+    return false;
+  unsigned Diff = UseNamespaces.size() - FromNamespaces.size();
+  auto FromIter = FromNamespaces.begin();
+  // Only compare `FromNamespaces` with namespaces in `UseNamespaces` that can
+  // collide, i.e. the top N namespaces where N is the number of namespaces in
+  // `FromNamespaces`.
+  auto UseIter = UseNamespaces.begin() + Diff;
+  for (; FromIter != FromNamespaces.end() && UseIter != UseNamespaces.end();
+       ++FromIter, ++UseIter) {
     // Literally the same namespace, not a collision.
-    if (DeclA == DeclB)
+    if (*FromIter == *UseIter)
       return false;
-
-    // Now check the names. If they match we have a different namespace with the
-    // same name.
-    if (cast<NamespaceDecl>(DeclA)->getDeclName() ==
-        cast<NamespaceDecl>(DeclB)->getDeclName())
+    // Now check the names. If they match we have a different canonical
+    // namespace with the same name.
+    if (cast<NamespaceDecl>(*FromIter)->getDeclName() ==
+        cast<NamespaceDecl>(*UseIter)->getDeclName())
       return true;
-
-    DeclA = DeclA->getParent();
-    DeclB = DeclB->getParent();
   }
+  assert(FromIter == FromNamespaces.end() && UseIter == UseNamespaces.end());
+  return false;
 }
 
 static StringRef getBestNamespaceSubstr(const DeclContext *DeclA,
@@ -90,16 +122,22 @@ std::string tooling::replaceNestedName(const NestedNameSpecifier *Use,
          "Expected fully-qualified name!");
 
   // We can do a raw name replacement when we are not inside the namespace for
-  // the original function and it is not in the global namespace.  The
+  // the original class/function and it is not in the global namespace.  The
   // assumption is that outside the original namespace we must have a using
   // statement that makes this work out and that other parts of this refactor
-  // will automatically fix using statements to point to the new function
+  // will automatically fix using statements to point to the new class/function.
+  // However, if the `FromDecl` is a class forward declaration, the reference is
+  // still considered as referring to the original definition, so we can't do a
+  // raw name replacement in this case.
   const bool class_name_only = !Use;
   const bool in_global_namespace =
       isa<TranslationUnitDecl>(FromDecl->getDeclContext());
-  if (class_name_only && !in_global_namespace &&
-      !isInsideDifferentNamespaceWithSameName(FromDecl->getDeclContext(),
-                                              UseContext)) {
+  const bool is_class_forward_decl =
+      isa<CXXRecordDecl>(FromDecl) &&
+      !cast<CXXRecordDecl>(FromDecl)->isCompleteDefinition();
+  if (class_name_only && !in_global_namespace && !is_class_forward_decl &&
+      !usingFromDifferentCanonicalNamespace(FromDecl->getDeclContext(),
+                                            UseContext)) {
     auto Pos = ReplacementString.rfind("::");
     return Pos != StringRef::npos ? ReplacementString.substr(Pos + 2)
                                   : ReplacementString;