[clangd] Disable expand auto on decltype(auto)

[ilya-biryukov]

Summary

Applying it produces incorrect code at the moment.

[kuhnel]

as the automatic build report did not work:

Failing Tests (1):
    LLVM :: tools/llvm-ar/mri-utf8.test

http://results.llvm-merge-guard.org/Phabricator-23/

[ilya-biryukov]

In D68630#1699371, @kuhnel wrote:

as the automatic build report did not work:

Definitely unrelated, llvm-ar does not depend on clangd... I think I was unlucky with the base revision...

clang-tools-extra/clangd/refactor/tweaks/ExpandAutoType.cpp

 
 std::string ExpandAutoType::title() const { return "Expand auto type"; }
 
 bool ExpandAutoType::prepare(const Selection& Inputs) {
   CachedLocation = llvm::None;
   if (auto *Node = Inputs.ASTSelection.commonAncestor()) {
     if (auto *TypeNode = Node->ASTNode.get<TypeLoc>()) {
       if (const AutoTypeLoc Result = TypeNode->getAs<AutoTypeLoc>()) {
+        // Code in apply() does handle 'decltype(auto)' yet.
+        if (!Result.getTypePtr()->isDecltypeAuto())
           CachedLocation = Result;
       }
     }
   }
   return (bool) CachedLocation;
 }
 
 Expected<Tweak::Effect> ExpandAutoType::apply(const Selection& Inputs) {
   auto& SrcMgr = Inputs.AST.getASTContext().getSourceManager();

clang-tools-extra/clangd/unittests/TweakTests.cpp

TEST_F(ExpandAutoTypeTest, Test) {
   EXPECT_EQ(apply("au^to x = inl_ns::Visible();"),
               "Visible x = inl_ns::Visible();");
   // local class
   EXPECT_EQ(apply("namespace x { void y() { struct S{}; ^auto z = S(); } }"),
             "namespace x { void y() { struct S{}; S z = S(); } }");
   // replace array types
   EXPECT_EQ(apply(R"cpp(au^to x = "test")cpp"),
             R"cpp(const char * x = "test")cpp");
+
+  EXPECT_UNAVAILABLE("dec^ltype(au^to) x = 10;");
 }
 
 TWEAK_TEST(ExtractFunction);
 TEST_F(ExtractFunctionTest, FunctionTest) {
   Context = Function;
 
   // Root statements should have common parent.
   EXPECT_EQ(apply("for(;;) [[1+2; 1+2;]]"), "unavailable");