[Tooling] skip anonymous namespaces when checking if typeLoc references a type decl from a different canonical namespace.

[ioeric]

Summary

[Tooling] skip anonymous namespaces when checking if typeLoc
references a type decl from a different canonical namespace.

cfe/trunk/lib/Tooling/Core/Lookup.cpp

 //
 //===----------------------------------------------------------------------===//
 
 #include "clang/Tooling/Core/Lookup.h"
 #include "clang/AST/Decl.h"
 using namespace clang;
 using namespace clang::tooling;
 
-static bool isInsideDifferentNamespaceWithSameName(const DeclContext *DeclA,
-                                                   const DeclContext *DeclB) {
+// 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) {
   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();
+    // Look past non-namespaces and anonymous namespaces on FromContext.
+    // 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.
+    while (FromContext &&
+           (!isa<NamespaceDecl>(FromContext) ||
+            cast<NamespaceDecl>(FromContext)->isAnonymousNamespace()))
+      FromContext = FromContext->getParent();
+
+    // Look past non-namespaces and anonymous namespaces on UseContext.
+    while (UseContext &&
+           (!isa<NamespaceDecl>(UseContext) ||
+            cast<NamespaceDecl>(UseContext)->isAnonymousNamespace()))
+      UseContext = UseContext->getParent();
 
     // We hit the root, no namespace collision.
-    if (!DeclA || !DeclB)
+    if (!FromContext || !UseContext)
       return false;
 
     // Literally the same namespace, not a collision.
-    if (DeclA == DeclB)
+    if (FromContext == UseContext)
       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())
+    if (cast<NamespaceDecl>(FromContext)->getDeclName() ==
+        cast<NamespaceDecl>(UseContext)->getDeclName())
       return true;
 
-    DeclA = DeclA->getParent();
-    DeclB = DeclB->getParent();
+    FromContext = FromContext->getParent();
+    UseContext = UseContext->getParent();
   }
 }
 
 static StringRef getBestNamespaceSubstr(const DeclContext *DeclA,
                                         StringRef NewName,
                                         bool HadLeadingColonColon) {
   while (true) {
     while (DeclA && !isa<NamespaceDecl>(DeclA))
std::string tooling::replaceNestedName(const NestedNameSpecifier *Use,
   // the original 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
   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)) {
+      !usingFromDifferentCanonicalNamespace(FromDecl->getDeclContext(),
     auto Pos = ReplacementString.rfind("::");
     return Pos != StringRef::npos ? ReplacementString.substr(Pos + 2)
                                   : ReplacementString;
   }
   // We did not match this because of a using statement, so we will need to
   // figure out how good a namespace match we have with our destination type.
   // We work backwards (from most specific possible namespace to least
   // specific).
   return getBestNamespaceSubstr(UseContext, ReplacementString,
                                 isFullyQualified(Use));
 }

cfe/trunk/unittests/Tooling/LookupTest.cpp

TEST(LookupTest, replaceNestedName) {
   };
   Visitor.runOver("namespace a { int foo(); }\nauto f = a::foo();\n");
 
   Visitor.OnCall = [&](CallExpr *Expr) {
     EXPECT_EQ("bar", replaceCallExpr(Expr, "::a::bar"));
   };
   Visitor.runOver(
       "namespace a { int foo(); }\nusing a::foo;\nauto f = foo();\n");
+
+  Visitor.OnCall = [&](CallExpr *Expr) {
+    EXPECT_EQ("c::bar", replaceCallExpr(Expr, "::a::c::bar"));
+  };
+  Visitor.runOver("namespace a { namespace b { void foo(); } }\n"
+                  "namespace a { namespace b { namespace {"
+                  "void f() { foo(); }"
+                  "} } }\n");
 }
 
 } // end anonymous namespace