[clang-diff] Fix matching for unnamed NamedDecs

[johannes]

Summary

This makes Node::getIdentifier return a valid value for special
NamedDecl nodes that do not have a name, such as ctors, dtors
and unnamed classes / namespaces.

[johannes]

update

lib/Tooling/ASTDiff/ASTDiff.cpp

static std::string getRelativeName(const NamedDecl *ND,
   if (auto *Namespace = dyn_cast<NamespaceDecl>(Context))
     ContextPrefix = Namespace->getQualifiedNameAsString();
   else if (auto *Tag = dyn_cast<TagDecl>(Context))
     ContextPrefix = Tag->getQualifiedNameAsString();
   std::string Val = ND->getQualifiedNameAsString();
   // Strip the qualifier, if Val refers to somthing in the current scope.
   // But leave one leading ':' in place, so that we know that this is a
   // relative path.
-  if (!ContextPrefix.empty() &&
-      StringRef(Val).startswith(ContextPrefix))
+  if (!ContextPrefix.empty() && StringRef(Val).startswith(ContextPrefix))
     Val = Val.substr(ContextPrefix.size() + 1);
   return Val;
 }
 
 static std::string getRelativeName(const NamedDecl *ND) {
   return getRelativeName(ND, ND->getDeclContext());
 }
 

 }
 
 StringRef Node::getTypeLabel() const { return getType().asStringRef(); }
 
 llvm::Optional<std::string> Node::getQualifiedIdentifier() const {
   if (auto *ND = ASTNode.get<NamedDecl>()) {
     if (ND->getDeclName().isIdentifier())
       return ND->getQualifiedNameAsString();
+    else
+      return std::string();
   }
   return llvm::None;
 }
 
 llvm::Optional<StringRef> Node::getIdentifier() const {
   if (auto *ND = ASTNode.get<NamedDecl>()) {
     if (ND->getDeclName().isIdentifier())
       return ND->getName();
+    else
+      return StringRef();
   }
   return llvm::None;
 }
 
 namespace {
 // Compares nodes by their depth.
 struct HeightLess {
   const SyntaxTree::Impl &Tree;

test/Tooling/clang-diff-heuristics.cpp

 // RUN: %clang_cc1 -E %s > %t.src.cpp
 // RUN: %clang_cc1 -E %s > %t.dst.cpp -DDEST
 // RUN: clang-diff -dump-matches -s=0 %t.src.cpp %t.dst.cpp -- | FileCheck %s
 //
 // Test the heuristics, with maxsize set to 0, so that the optimal matching will never be applied.
 
 #ifndef DEST
 
 void f1() {;}
 
 void f2(int) {;}
 
+class C3 { C3(); };
+
 #else
 
 // same parents, same value
 // CHECK: Match FunctionDecl: f1(void ())(1) to FunctionDecl: f1(void ())(1)
 // CHECK: Match CompoundStmt
 void f1() {}
 
 // same parents, same identifier
 // CHECK: Match FunctionDecl: f2(void (int))(4) to FunctionDecl: f2(void ())(3)
 // CHECK: Match CompoundStmt
 void f2() {}
 
+// same parents, same identifier
+// CHECK: Match CXXConstructorDecl: :C3(void ())(9) to CXXConstructorDecl: :C3(void (int))(6)
+class C3 { C3(int); };
+
 #endif