[clang][tooling] Fix `name` range-selector to handle TypeLocs correctly.

[ymandel]

Summary

Previously, where name was applied to a template-specialization TypeLoc, it
returned the entire specialization (name, brackets, args) rather than just the
name identifier. With this change, exactly the name token is selected.

[li.zhe.hua]

clang/lib/Tooling/Transformer/RangeSelector.cpp

239–240

Optional: If the token range is only one token, you can specify a single location that is the start of the token.

clang/unittests/Tooling/RangeSelectorTest.cpp

493

Nit: Is the data member necessary?

[ymandel]

address comments

[ymandel]

clang-format

[ymandel]

tweak

clang/lib/Tooling/Transformer/RangeSelector.cpp

if (const auto *I = Node.get<CXXCtorInitializer>()) {
       if (!I->isMemberInitializer() && I->isWritten())
         return missingPropertyError(ID, "name", "explicit member initializer");
       SourceLocation L = I->getMemberLocation();
       return CharSourceRange::getTokenRange(L, L);
     }
     if (const auto *T = Node.get<TypeLoc>()) {
       TypeLoc Loc = *T;
       auto ET = Loc.getAs<ElaboratedTypeLoc>();
-      if (!ET.isNull()) {
+      if (!ET.isNull())
         Loc = ET.getNamedTypeLoc();
-      }
+      if (auto SpecLoc = Loc.getAs<TemplateSpecializationTypeLoc>();
+          !SpecLoc.isNull())
+        return CharSourceRange::getTokenRange(SpecLoc.getTemplateNameLoc());
       return CharSourceRange::getTokenRange(Loc.getSourceRange());
     }
     return typeError(ID, Node.getNodeKind(),
                      "DeclRefExpr, NamedDecl, CXXCtorInitializer, TypeLoc");
   };
 }
 
 namespace {
 // FIXME: make this available in the public API for users to easily create their

clang/unittests/Tooling/RangeSelectorTest.cpp

TestMatch MatchB = matchCode(
       Code, cxxFunctionalCastExpr(hasTypeLoc(typeLoc().bind(CtorTy))));
   EXPECT_THAT_EXPECTED(select(name(CtorTy), MatchB), HasValue("Foo"));
   // Matches call of Foo(int, int)
   TestMatch MatchC = matchCode(
       Code, cxxTemporaryObjectExpr(hasTypeLoc(typeLoc().bind(CtorTy))));
   EXPECT_THAT_EXPECTED(select(name(CtorTy), MatchC), HasValue("Foo"));
 }
 
+TEST(RangeSelectorTest, NameOpTemplateSpecializationTypeLoc) {
+  StringRef Code = R"cc(
+    namespace ns {
+    template <typename T>
+    struct Foo {};
+    }  // namespace ns
+
+    ns::Foo<int> a;
+  )cc";
+  const char *Loc = "tyloc";
+  // Matches declaration of `a`.
+  TestMatch MatchA =
+      matchCode(Code, varDecl(hasName("a"), hasTypeLoc(typeLoc().bind(Loc))));
+  EXPECT_THAT_EXPECTED(select(name(Loc), MatchA), HasValue("Foo"));
+}
+
 TEST(RangeSelectorTest, NameOpErrors) {
   EXPECT_THAT_EXPECTED(selectFromTrivial(name("unbound_id")),
                        Failed<StringError>(withUnboundNodeMessage()));
   EXPECT_THAT_EXPECTED(selectFromAssorted(name("stmt")),
                        Failed<StringError>(withTypeErrorMessage("stmt")));
 }
 
 TEST(RangeSelectorTest, NameOpDeclRefError) {