[clang] Pass FoundDecl to DeclRefExpr creator for operator overloads

[SimplyDanny]

Summary

Without the "found declaration" it is later not possible to know where the operator declaration
was brought into the scope calling it.

The initial motivation for this fix came from #55095. However, this also has an influence on
clang -ast-dump which now prints a UsingShadow attribute for operators only visible through
using statements. Also, clangd now correctly references the using statement instead of the
operator directly.

[shafik]

Thank you for working on this.

It looks like there are some pre-commit test failures, did you confirm whether they were related to your change or not?

Also you mentioned that this changes the output of -ast-dump it might be worth adding a test to capture this behavior change.

clang/unittests/ASTMatchers/ASTMatchersTraversalTest.cpp

4679

You have a trailing ; after the definition of a::operator+ please remove it.

[SimplyDanny]

Added a test for the AST dump and updated some test references.

[SimplyDanny]

clang/test/Index/annotate-operator-call-expr.cpp

21

I updated the test expectation without actually knowing whether the test references are correct(er) now. There seems to be some loss of information and some CallExprs are now seen as DeclRefExprs. Please tell me if these changes are okay. I rather made them to have a basis for discussions.

clang/unittests/ASTMatchers/ASTMatchersTraversalTest.cpp

4679

Made it a declaration which is sufficient for the test.

[SimplyDanny]

clang/test/AST/ast-dump-overloaded-operators.cpp

65

This verifies the AST dump. The new part is the UsingShadow at the end of this line.

[SimplyDanny]

Rebased commit onto current main branch.

[SimplyDanny]

Fixed formatting.

[shafik]

LGTM

clang/test/Index/annotate-operator-call-expr.cpp

21

DeclRerExpr to CallExpr looks right.

clang/test/Index/cursor-ref-names.cpp

36

It looks like we lost some information here but I am not sure if that is expected or not.

AFAIK CIndex is supported on a best effort basis, I think this is ok.

[SimplyDanny]

Thank you for the review! Before I push the change into main I may add an entry to clang/docs/ReleaseNotes.rst, right?

And do you agree that the test failures are unrelated to my change? It looks like they are all located in libomptarget caused by a linker error.

[SimplyDanny]

In D129973#3673094, @SimplyDanny wrote:

Thank you for the review! Before I push the change into main I may add an entry to clang/docs/ReleaseNotes.rst, right?

And do you agree that the test failures are unrelated to my change? It looks like they are all located in libomptarget caused by a linker error.

@shafik: Could you give one last feedback on this?

[shafik]

In D129973#3673094, @SimplyDanny wrote:

Thank you for the review! Before I push the change into main I may add an entry to clang/docs/ReleaseNotes.rst, right?

Yes, please add an entry in the release notes.

And do you agree that the test failures are unrelated to my change? It looks like they are all located in libomptarget caused by a linker error.

They don't look related but as always you should be ready to revert if any of the builds break in a way that you can't fix quickly.

[yvvan]

With this change we don't pass "LocInfo" directly and it seems to break the locations when calling "getCXXOperatorNameRange" for this DeclRefExpr later on. Please fix it. You can introduce another "Create" static method for DeclRefExpr that accepts LocInfo and passes it to the DeclarationNameInfo constructor.

[SimplyDanny]

In D129973#3684940, @yvvan wrote:

With this change we don't pass "LocInfo" directly and it seems to break the locations when calling "getCXXOperatorNameRange" for this DeclRefExpr later on. Please fix it. You can introduce another "Create" static method for DeclRefExpr that accepts LocInfo and passes it to the DeclarationNameInfo constructor.

Thank you for the hint! This indeed "fixes" the test references so that they can be reverted to their original state. This is done in D130799.

Instead of a new create method or a new constructor (there are already quite a lot of them with complex signatures), I created a DeclarationNameInfo and passed it to one of the existing creators.

[yvvan]

In D129973#3688329, @SimplyDanny wrote:

In D129973#3684940, @yvvan wrote:

With this change we don't pass "LocInfo" directly and it seems to break the locations when calling "getCXXOperatorNameRange" for this DeclRefExpr later on. Please fix it. You can introduce another "Create" static method for DeclRefExpr that accepts LocInfo and passes it to the DeclarationNameInfo constructor.

Thank you for the hint! This indeed "fixes" the test references so that they can be reverted to their original state. This is done in D130799.

Instead of a new create method or a new constructor (there are already quite a lot of them with complex signatures), I created a DeclarationNameInfo and passed it to one of the existing creators.

Thank you!

[joanahalili]

Heads up: This commit causes clang crashes on our end. We are currently working on a reproducer and will post it as soon as its ready.

[joanahalili]

In D129973#3696189, @joanahalili wrote:

Heads up: This commit causes clang crashes on our end. We are currently working on a reproducer and will post it as soon as its ready.

Here is the reduced code:

template <class a> struct b {
  template <class c> void ab(c);
  template <class c> void ad(c p1) { ab(d()(p1)); }
  a d();
};
template <typename e> struct f {
  using aa = e;
  template <class g> struct j {
    g ag;
    template <class... h> auto operator()(h... p1) -> decltype(ag(p1...));
  };
  using ai = b<j<aa>>;
  template <class c> void ad(c p1) { i.ad(p1); }
  ai i;
};
template <typename c, typename> struct l {
  int k(const c &);
  struct n {
    int operator()(const c &) const;
  };
  using m = f<n>;
  m aj;
};
template <typename c, typename al> int l<c, al>::k(const c &p1) { aj.ad(p1); }
template <typename c, typename al>
int l<c, al>::n::operator()(const c &) const {}
template class l<int, int>;

This commit causes a compiler crash for this code. It however successfully builds with the previous commit compiler.
Here is also a link comparing released clang with clang trunk where trunk is crashing and the released version is not: https://godbolt.org/z/fdbo74c54

Please revert!

[asmok-g]

This is also causing a compilation error in some google third-party code. Compiling with older clang doesn't give that error. Error:

error: no matching function for call to object of type 'key_compare_adapter<QuicIntervalSet<long>::IntervalLess>::checked_compare'
    comp(__trans_tmp_3, k);
    ^~~~
/tmp/pre.ii:85:5: note: in instantiation of function template specialization 'btree_node<set_params<QuicIntervalSet<long>::IntervalLess>>::linear_search_impl<int, key_compare_adapter<QuicIntervalSet<long>::IntervalLess>::checked_compare>' requested here
    linear_search_impl(k, 0, 0, comp,
    ^
/tmp/pre.ii:76:32: note: in instantiation of function template specialization 'btree_node<set_params<QuicIntervalSet<long>::IntervalLess>>::linear_search<int, key_compare_adapter<QuicIntervalSet<long>::IntervalLess>::checked_compare>' requested here
    use_linear_search::value ? linear_search(k, comp) : binary_search(k, comp);
                               ^
/tmp/pre.ii:123:15: note: in instantiation of function template specialization 'btree_node<set_params<QuicIntervalSet<long>::IntervalLess>>::lower_bound<int>' requested here
  iter.node_->lower_bound(key, key_comp());
              ^
/tmp/pre.ii:111:51: note: in instantiation of function template specialization 'btree<set_params<QuicIntervalSet<long>::IntervalLess>>::internal_lower_bound<int>' requested here
  template <typename K> void lower_bound(K key) { internal_lower_bound(key); }
                                                  ^
/tmp/pre.ii:133:37: note: in instantiation of function template specialization 'btree<set_params<QuicIntervalSet<long>::IntervalLess>>::lower_bound<int>' requested here
  void lower_bound(int key) { tree_.lower_bound(key); }
                                    ^
/tmp/pre.ii:164:14: note: in instantiation of member function 'btree_container<btree<set_params<QuicIntervalSet<long>::IntervalLess>>>::lower_bound' requested here
  intervals_.lower_bound(0);
             ^
/tmp/pre.ii:158:16: note: in instantiation of member function 'QuicIntervalSet<long>::Add' requested here
  void Add() { Add(value_type(Add_min, Add_max)); }
               ^
/tmp/pre.ii:190:34: note: in instantiation of member function 'QuicIntervalSet<long>::Add' requested here
  unacked_frame_headers_offsets_.Add();
                                 ^
/tmp/pre.ii:44:10: note: candidate template ignored: substitution failure [with T = QuicInterval, U = int]
    void operator()(T lhs, U rhs) {

I attached the preprocessed file for the case

pre.ii7 KBDownload

.

The commande to reproduce is: clang -msse4.2 -O1 -fsized-deallocation -std=gnu++17 -c pre.ii

[bgraur]

@SimplyDanny given the reports from @joanahalili and @asmok-g are you considering a revert for this patch?

[bgraur]

@tstellar FYI the clang crash report from @joanahalili and the new compilation errors report from @asmok-g, both introduced by this patch.
Is a revert warranted here?

[kadircet]

Reverting for @bgraur as he's having some issues with his commit access ATM. To sum up the reproducer attached by @joanahalili triggers a crash https://reviews.llvm.org/rG4e94f6653150511de434fa7e29b684ae7f0e52b6 with stack trace and error:

$ ~/repos/llvm/build/bin/clang -xc++ -c a.cc
a.cc:3:38: error: cannot compile this l-value expression yet
  template <class c> void ad(c p1) { ab(d()(p1)); }
                                     ^~
Unexpected placeholder builtin type!
UNREACHABLE executed at /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenTypes.cpp:641!
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: /usr/local/google/home/kadircet/repos/llvm/build/bin/clang -xc++ -c a.cc
1.      <eof> parser at end of file
2.      Per-file LLVM IR generation
3.      a.cc:3:27: Generating code for declaration 'b<f<l<int, int>::n>::j<l<int, int>::n>>::ad'
 #0 0x00000000064fb563 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/Unix/Signals.inc:569:13
 #1 0x00000000064f92fe llvm::sys::RunSignalHandlers() /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/Signals.cpp:104:18
 #2 0x000000000645f823 (anonymous namespace)::CrashRecoveryContextImpl::HandleCrash(int, unsigned long) /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/CrashRecoveryContext.cpp:76:5
 #3 0x000000000645f9de CrashRecoverySignalHandler(int) /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/CrashRecoveryContext.cpp:390:1
 #4 0x00007f8c235bf200 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x12200)
 #5 0x00007f8c2302c8a1 raise ./signal/../sysdeps/unix/sysv/linux/raise.c:50:1
 #6 0x00007f8c23016546 abort ./stdlib/abort.c:81:7
 #7 0x0000000006465531 (/usr/local/google/home/kadircet/repos/llvm/build/bin/clang+0x6465531)
 #8 0x000000000689b09f (/usr/local/google/home/kadircet/repos/llvm/build/bin/clang+0x689b09f)
 #9 0x00000000068be0f1 clang::CodeGen::CodeGenFunction::EmitUnsupportedLValue(clang::Expr const*, char const*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExpr.cpp:1250:22
#10 0x00000000068b4703 clang::CodeGen::CodeGenFunction::EmitLValue(clang::Expr const*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExpr.cpp:0:19
#11 0x00000000068d3fab isSimple /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGValue.h:265:41
#12 0x00000000068d3fab getPointer /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGValue.h:338:5
#13 0x00000000068d3fab clang::CodeGen::CodeGenFunction::EmitCallee(clang::Expr const*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExpr.cpp:5131:31
#14 0x00000000068d3c72 isBuiltin /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGCall.h:151:12
#15 0x00000000068d3c72 clang::CodeGen::CodeGenFunction::EmitCallExpr(clang::CallExpr const*, clang::CodeGen::ReturnValueSlot) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExpr.cpp:5014:14
#16 0x00000000069e0518 getInt /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/PointerIntPair.h:62:57
#17 0x00000000069e0518 isScalar /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGValue.h:54:37
#18 0x00000000069e0518 getScalarVal /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGValue.h:62:5
#19 0x00000000069e0518 (anonymous namespace)::ScalarExprEmitter::VisitCallExpr(clang::CallExpr const*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExprScalar.cpp:578:36
#20 0x00000000069e1338 Visit /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExprScalar.cpp:408:52
#21 0x00000000069e1338 (anonymous namespace)::ScalarExprEmitter::VisitExprWithCleanups(clang::ExprWithCleanups*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExprScalar.cpp:2447:14
#22 0x00000000069d1128 Visit /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExprScalar.cpp:408:52
#23 0x00000000069d1128 clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExprScalar.cpp:4874:8
#24 0x00000000068b3a47 PointerIntPair /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/PointerIntPair.h:49:12
#25 0x00000000068b3a47 RValue /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGValue.h:39:7
#26 0x00000000068b3a47 get /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGValue.h:90:12
#27 0x00000000068b3a47 clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExpr.cpp:217:12
#28 0x00000000068b39d1 clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGExpr.cpp:206:1
#29 0x00000000068f2755 GetInsertBlock /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/IR/IRBuilder.h:173:47
#30 0x00000000068f2755 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGStmt.cpp:123:42
#31 0x00000000068ff680 clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CGStmt.cpp:496:22
#32 0x00000000068e26fd clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenFunction.cpp:0:5
#33 0x00000000068e341e getLangOpts /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenFunction.h:1991:51
#34 0x00000000068e341e clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenFunction.cpp:1443:7
#35 0x0000000006844ca5 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenModule.cpp:5234:3
#36 0x000000000683d0cc clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenModule.cpp:0:9
#37 0x000000000682dea0 __normal_iterator /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_iterator.h:1027:20
#38 0x000000000682dea0 begin /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_vector.h:821:16
#39 0x000000000682dea0 empty /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_vector.h:1008:16
#40 0x000000000682dea0 clang::CodeGen::CodeGenModule::EmitDeferred() /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenModule.cpp:2675:26
#41 0x000000000682decc __normal_iterator /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_iterator.h:1027:20
#42 0x000000000682decc begin /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_vector.h:821:16
#43 0x000000000682decc empty /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_vector.h:1008:16
#44 0x000000000682decc clang::CodeGen::CodeGenModule::EmitDeferred() /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenModule.cpp:2677:7
#45 0x000000000682ba4a clang::CodeGen::CodeGenModule::Release() /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenModule.cpp:525:3
#46 0x0000000007169194 (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit(clang::ASTContext&) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/ModuleBuilder.cpp:287:11
#47 0x000000000716660e clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) /usr/local/google/home/kadircet/repos/llvm/clang/lib/CodeGen/CodeGenAction.cpp:306:13
#48 0x000000000842759a __normal_iterator /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_iterator.h:1027:20
#49 0x000000000842759a begin /usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/bits/stl_vector.h:812:16
#50 0x000000000842759a finalize<std::vector<std::unique_ptr<clang::TemplateInstantiationCallback, std::default_delete<clang::TemplateInstantiationCallback> >, std::allocator<std::unique_ptr<clang::TemplateInstantiationCallback, std::default_delete<clang::TemplateInstantiationCallback> > > > > /usr/local/google/home/kadircet/repos/llvm/clang/include/clang/Sema/TemplateInstCallback.h:54:16
#51 0x000000000842759a clang::ParseAST(clang::Sema&, bool, bool) /usr/local/google/home/kadircet/repos/llvm/clang/lib/Parse/ParseAST.cpp:205:3
#52 0x000000000708bff0 clang::FrontendAction::Execute() /usr/local/google/home/kadircet/repos/llvm/clang/lib/Frontend/FrontendAction.cpp:1041:10
#53 0x0000000006ffd11f getPtr /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/Support/Error.h:271:42
#54 0x0000000006ffd11f operator bool /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/Support/Error.h:234:16
#55 0x0000000006ffd11f clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) /usr/local/google/home/kadircet/repos/llvm/clang/lib/Frontend/CompilerInstance.cpp:1035:23
#56 0x000000000715ff73 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /usr/local/google/home/kadircet/repos/llvm/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:266:25
#57 0x000000000409958a cc1_main(llvm::ArrayRef<char const*>, char const*, void*) /usr/local/google/home/kadircet/repos/llvm/clang/tools/driver/cc1_main.cpp:250:15
#58 0x0000000004096e30 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) /usr/local/google/home/kadircet/repos/llvm/clang/tools/driver/driver.cpp:317:12
#59 0x0000000006e75bc2 operator() /usr/local/google/home/kadircet/repos/llvm/clang/lib/Driver/Job.cpp:407:30
#60 0x0000000006e75bc2 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::$_1>(long) /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/STLFunctionalExtras.h:45:12
#61 0x000000000645f737 operator() /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/STLFunctionalExtras.h:0:12
#62 0x000000000645f737 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) /usr/local/google/home/kadircet/repos/llvm/llvm/lib/Support/CrashRecoveryContext.cpp:425:3
#63 0x0000000006e75600 clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const /usr/local/google/home/kadircet/repos/llvm/clang/lib/Driver/Job.cpp:407:7
#64 0x0000000006e37329 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const /usr/local/google/home/kadircet/repos/llvm/clang/lib/Driver/Compilation.cpp:200:15
#65 0x0000000006e3760e clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const /usr/local/google/home/kadircet/repos/llvm/clang/lib/Driver/Compilation.cpp:254:13
#66 0x0000000006e543c0 empty /usr/local/google/home/kadircet/repos/llvm/llvm/include/llvm/ADT/SmallVector.h:73:47
#67 0x0000000006e543c0 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) /usr/local/google/home/kadircet/repos/llvm/clang/lib/Driver/Driver.cpp:1738:23
#68 0x000000000409644f clang_main(int, char**) /usr/local/google/home/kadircet/repos/llvm/clang/tools/driver/driver.cpp:513:21
#69 0x00007f8c230177fd __libc_start_main ./csu/../csu/libc-start.c:332:16
#70 0x00000000040938ba _start (/usr/local/google/home/kadircet/repos/llvm/build/bin/clang+0x40938ba)

Whereas the same code fragment at previous commit https://reviews.llvm.org/rG0538e5431afdb1fa05bdcedf70ee502ccfcd112a yields an diagnostics and crash free compile.

A little bit adjusted reproducer to get rid of warnings:

$ cat a.cc
template <class a> struct b {
  template <class c> void ab(c);
  template <class c> void ad(c p1) { ab(d()(p1)); }
  a d();
};
template <typename e> struct f {
  using aa = e;
  template <class g> struct j {
    g ag;
    template <class... h> auto operator()(h... p1) -> decltype(ag(p1...));
  };
  using ai = b<j<aa>>;
  template <class c> void ad(c p1) { i.ad(p1); }
  ai i;
};
template <typename c, typename> struct l {
  void k(const c &);
  struct n {
    int operator()(const c &) const;
  };
  using m = f<n>;
  m aj;
};
template <typename c, typename al> void l<c, al>::k(const c &p1) { aj.ad(p1); }
template <typename c, typename al>
int l<c, al>::n::operator()(const c &) const {
  return 0;
}
template class l<int, int>;

[kadircet]

Reverted in df48e3fbcc8be1f4c04bd97517d12e662f54de75, @tstellar it needs to be cherry-picked into release branch as well.

[tstellar]

In D129973#3699055, @kadircet wrote:

Reverted in df48e3fbcc8be1f4c04bd97517d12e662f54de75, @tstellar it needs to be cherry-picked into release branch as well.

Thanks for letting me know, I will make sure this gets backported: https://github.com/llvm/llvm-project/issues/56928

[Hahnfeld]

FWIW this also causes a static_assert failure while building ROOT:

In file included from /home/jhahnfel/ROOT/src/tmva/tmva/src/DNN/Architectures/Cpu/CpuBuffer.cxx:17:
In file included from /opt/rh/gcc-toolset-11/root/usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/memory:77:
In file included from /opt/rh/gcc-toolset-11/root/usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/bits/shared_ptr.h:53:
/opt/rh/gcc-toolset-11/root/usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/bits/shared_ptr_base.h:1110:4: error: static assertion failed due to requirement '__is_invocable<TMVA::DNN::TCpuBuffer<double>::TDestructor &, double **&>::value': deleter expression d(p) is well-formed
          static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
          ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/rh/gcc-toolset-11/root/usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/bits/shared_ptr.h:178:11: note: in instantiation of function template specialization 'std::__shared_ptr<double *, __gnu_cxx::_S_atomic>::__shared_ptr<double *, TMVA::DNN::TCpuBuffer<double>::TDestructor, void>' requested here
        : __shared_ptr<_Tp>(__p, std::move(__d)) { }
          ^
/home/jhahnfel/ROOT/src/tmva/tmva/src/DNN/Architectures/Cpu/CpuBuffer.cxx:42:14: note: in instantiation of function template specialization 'std::shared_ptr<double *>::shared_ptr<double *, TMVA::DNN::TCpuBuffer<double>::TDestructor, void>' requested here
   fBuffer = std::shared_ptr<AReal *>(pointer, fDestructor);
             ^

After the revert, at least this issue is gone when building with current main.

[vient]

FWIW this also causes compilation error on correct code using Boost: https://github.com/llvm/llvm-project/issues/56878

[tstellar]

The revert doesn't apply cleanly, can someone try to fix it up: https://github.com/llvm/llvm-project/issues/56928#issuecomment-1205483442

clang-tools-extra/docs/ReleaseNotes.rst

- Fixed false positives in :doc:`misc-redundant-expression
   - Fixed a false positive involving assignments in
     conditions. This fixes `Issue 35853 <https://github.com/llvm/llvm-project/issues/35853>`_.
 
 - Fixed a false positive in :doc:`misc-unused-parameters
   <clang-tidy/checks/misc/unused-parameters>`
   where invalid parameters were implicitly being treated as being unused. 
   This fixes `Issue 56152 <https://github.com/llvm/llvm-project/issues/56152>`_.
 
+- Fixed false positives in :doc:`misc-unused-using-decls
+  <clang-tidy/checks/misc/unused-using-decls>` where `using` statements bringing
+  operators into the scope where incorrectly marked as unused. 
+  This fixes `issue 55095 <https://github.com/llvm/llvm-project/issues/55095>`_.
+
 - Fixed a false positive in :doc:`modernize-deprecated-headers
   <clang-tidy/checks/modernize/deprecated-headers>` involving including
   C header files from C++ files wrapped by ``extern "C" { ... }`` blocks.
   Such includes will be ignored by now.
   By default now it doesn't warn for including deprecated headers from header
   files, since that header file might be used from C source files. By passing
   the ``CheckHeaderFile=true`` option if header files of the project only
   included by C++ source files.

clang-tools-extra/test/clang-tidy/checkers/misc/unused-using-decls.cpp

 template <int T>
 void i(n::P<T>* t) {}
 template void i(n::P<Constant>* t);
 
 template <typename T, template <typename> class U> class Bar {};
 // We used to report Q unsued, because we only checked the first template
 // argument.
 Bar<int, Q> *bar;
+
+namespace internal { 
+  struct S {};
+  int operator+(S s1, S s2);
+} 
+
+// Make sure this statement is not reported as unused.
+using internal::operator+; 
+using internal::S;
+
+int j() { return S() + S(); }

clang/docs/ReleaseNotes.rst

 - Fix that ``if consteval`` could evaluate to ``true`` at runtime because it was incorrectly
   constant folded. Fixes `Issue 55638 <https://github.com/llvm/llvm-project/issues/55638>`_.
 - Fixed incompatibility of Clang's ``<stdatomic.h>`` with MSVC ``<atomic>``.
   Fixes `MSVC STL Issue 2862 <https://github.com/microsoft/STL/issues/2862>`_.
 - Empty enums and enums with a single enumerator with value zero will be
   considered to have one positive bit in order to represent the underlying
   value. This effects whether we consider the store of the value one to be well
   defined.
+- An operator introduced to the scope via a `using` statement now correctly references this
+  statement in clangd (hover over the symbol, jump to definition) as well as in the AST dump.
+  This also fixes `issue 55095 <https://github.com/llvm/llvm-project/issues/#55095>`_ as a
+  side-effect.
 
 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 - ``-Wliteral-range`` will warn on floating-point equality comparisons with
   constants that are not representable in a casted value. For example,
   ``(float) f == 0.1`` is always false.
 - ``-Winline-namespace-reopened-noninline`` now takes into account that the
   ``inline`` keyword must appear on the original but not necessarily all

clang/lib/Sema/SemaOverload.cpp

static ExprResult CreateFunctionRefExpr(
   // If FoundDecl is different from Fn (such as if one is a template
   // and the other a specialization), make sure DiagnoseUseOfDecl is
   // called on both.
   // FIXME: This would be more comprehensively addressed by modifying
   // DiagnoseUseOfDecl to accept both the FoundDecl and the decl
   // being used.
   if (FoundDecl != Fn && S.DiagnoseUseOfDecl(Fn, Loc))
     return ExprError();
-  DeclRefExpr *DRE = new (S.Context)
-      DeclRefExpr(S.Context, Fn, false, Fn->getType(), VK_LValue, Loc, LocInfo);
+  DeclRefExpr *DRE =
+      DeclRefExpr::Create(S.Context, Fn->getQualifierLoc(), SourceLocation(),
+                          Fn, false, Loc, Fn->getType(), VK_LValue, FoundDecl);
   if (HadMultipleCandidates)
     DRE->setHadMultipleCandidates(true);
 
   S.MarkDeclRefReferenced(DRE, Base);
   if (auto *FPT = DRE->getType()->getAs<FunctionProtoType>()) {
     if (isUnresolvedExceptionSpec(FPT->getExceptionSpecType())) {
       S.ResolveExceptionSpec(Loc, FPT);
       DRE->setType(Fn->getType());

clang/test/AST/ast-dump-overloaded-operators.cpp

 // CHECK: TranslationUnitDecl {{.*}} <<invalid sloc>> <invalid sloc>{{( <undeserialized declarations>)?}}
 // CHECK: |-EnumDecl {{.*}} <{{.*}}ast-dump-overloaded-operators.cpp:10:1, col:9> col:6{{( imported)?}} referenced E
 // CHECK-NEXT: |-FunctionDecl {{.*}} <line:11:1, col:19> col:6{{( imported)?}} used operator+ 'void (E, E)'
 // CHECK-NEXT: | |-ParmVarDecl {{.*}} <col:16> col:17{{( imported)?}} 'E'
 // CHECK-NEXT: | `-ParmVarDecl {{.*}} <col:18> col:19{{( imported)?}} 'E'
 // CHECK-NEXT: |-FunctionDecl {{.*}} <line:12:1, col:19> col:6{{( imported)?}} used operator, 'void (E, E)'
 // CHECK-NEXT: | |-ParmVarDecl {{.*}} <col:16> col:17{{( imported)?}} 'E'
 // CHECK-NEXT: | `-ParmVarDecl {{.*}} <col:18> col:19{{( imported)?}} 'E'
-// CHECK-NEXT: `-FunctionDecl {{.*}} <line:14:1, line:18:1> line:14:6{{( imported)?}} test 'void ()'
-// CHECK-NEXT:   `-CompoundStmt {{.*}} <col:13, line:18:1>
-// CHECK-NEXT:     |-DeclStmt {{.*}} <line:15:3, col:6>
-// CHECK-NEXT:     | `-VarDecl {{.*}} <col:3, col:5> col:5{{( imported)?}} used e 'E'
-// CHECK-NEXT:     |-CXXOperatorCallExpr {{.*}} <line:16:3, col:7> 'void' '+'
-// CHECK-NEXT:     | |-ImplicitCastExpr {{.*}} <col:5> 'void (*)(E, E)' <FunctionToPointerDecay>
-// CHECK-NEXT:     | | `-DeclRefExpr {{.*}} <col:5> 'void (E, E)' lvalue Function {{.*}} 'operator+' 'void (E, E)'
-// CHECK-NEXT:     | |-ImplicitCastExpr {{.*}} <col:3> 'E' <LValueToRValue>
-// CHECK-NEXT:     | | `-DeclRefExpr {{.*}} <col:3> 'E' lvalue Var {{.*}} 'e' 'E'
-// CHECK-NEXT:     | `-ImplicitCastExpr {{.*}} <col:7> 'E' <LValueToRValue>
-// CHECK-NEXT:     |   `-DeclRefExpr {{.*}} <col:7> 'E' lvalue Var {{.*}} 'e' 'E'
-// CHECK-NEXT:     `-CXXOperatorCallExpr {{.*}} <line:17:3, col:7> 'void' ','
-// CHECK-NEXT:       |-ImplicitCastExpr {{.*}} <col:5> 'void (*)(E, E)' <FunctionToPointerDecay>
-// CHECK-NEXT:       | `-DeclRefExpr {{.*}} <col:5> 'void (E, E)' lvalue Function {{.*}} 'operator,' 'void (E, E)'
-// CHECK-NEXT:       |-ImplicitCastExpr {{.*}} <col:3> 'E' <LValueToRValue>
-// CHECK-NEXT:       | `-DeclRefExpr {{.*}} <col:3> 'E' lvalue Var {{.*}} 'e' 'E'
-// CHECK-NEXT:       `-ImplicitCastExpr {{.*}} <col:7> 'E' <LValueToRValue>
-// CHECK-NEXT:         `-DeclRefExpr {{.*}} <col:7> 'E' lvalue Var {{.*}} 'e' 'E'
+// CHECK-NEXT: |-FunctionDecl {{.*}} <line:14:1, line:18:1> line:14:6{{( imported)?}} test 'void ()'
+// CHECK-NEXT: | `-CompoundStmt {{.*}} <col:13, line:18:1>
+// CHECK-NEXT: |   |-DeclStmt {{.*}} <line:15:3, col:6>
+// CHECK-NEXT: |   | `-VarDecl {{.*}} <col:3, col:5> col:5{{( imported)?}} used e 'E'
+// CHECK-NEXT: |   |-CXXOperatorCallExpr {{.*}} <line:16:3, col:7> 'void' '+'
+// CHECK-NEXT: |   | |-ImplicitCastExpr {{.*}} <col:5> 'void (*)(E, E)' <FunctionToPointerDecay>
+// CHECK-NEXT: |   | | `-DeclRefExpr {{.*}} <col:5> 'void (E, E)' lvalue Function {{.*}} 'operator+' 'void (E, E)'
+// CHECK-NEXT: |   | |-ImplicitCastExpr {{.*}} <col:3> 'E' <LValueToRValue>
+// CHECK-NEXT: |   | | `-DeclRefExpr {{.*}} <col:3> 'E' lvalue Var {{.*}} 'e' 'E'
+// CHECK-NEXT: |   | `-ImplicitCastExpr {{.*}} <col:7> 'E' <LValueToRValue>
+// CHECK-NEXT: |   |   `-DeclRefExpr {{.*}} <col:7> 'E' lvalue Var {{.*}} 'e' 'E'
+// CHECK-NEXT: |   `-CXXOperatorCallExpr {{.*}} <line:17:3, col:7> 'void' ','
+// CHECK-NEXT: |     |-ImplicitCastExpr {{.*}} <col:5> 'void (*)(E, E)' <FunctionToPointerDecay>
+// CHECK-NEXT: |     | `-DeclRefExpr {{.*}} <col:5> 'void (E, E)' lvalue Function {{.*}} 'operator,' 'void (E, E)'
+// CHECK-NEXT: |     |-ImplicitCastExpr {{.*}} <col:3> 'E' <LValueToRValue>
+// CHECK-NEXT: |     | `-DeclRefExpr {{.*}} <col:3> 'E' lvalue Var {{.*}} 'e' 'E'
+// CHECK-NEXT: |     `-ImplicitCastExpr {{.*}} <col:7> 'E' <LValueToRValue>
+// CHECK-NEXT: |       `-DeclRefExpr {{.*}} <col:7> 'E' lvalue Var {{.*}} 'e' 'E'
+
+namespace a {
+  void operator-(E, E);
+}
+
+using a::operator-;
+
+void f() {
+  E() - E();
+}
+// CHECK: |-NamespaceDecl {{.*}} <line:46:1, line:48:1> line:46:11{{( imported <undeserialized declarations>)?}} a
+// CHECK-NEXT: | `-FunctionDecl {{.*}} <line:47:3, col:22> col:8{{( imported)?}} used operator- 'void (E, E)'
+// CHECK-NEXT: |   |-ParmVarDecl {{.*}} <col:18> col:19{{( imported)?}} 'E'
+// CHECK-NEXT: |   `-ParmVarDecl {{.*}} <col:21> col:22{{( imported)?}} 'E'
+// CHECK-NEXT: |-UsingDecl {{.*}} <line:50:1, col:18> col:10{{( imported)?}} a::operator-
+// CHECK-NEXT: |-UsingShadowDecl {{.*}} <col:10> col:10{{( imported)?}} implicit Function {{.*}} 'operator-' 'void (E, E)'
+// CHECK-NEXT: `-FunctionDecl {{.*}} <line:52:1, line:54:1> line:52:6{{( imported)?}} f 'void ()'
+// CHECK-NEXT:   `-CompoundStmt {{.*}} <col:10, line:54:1>
+// CHECK-NEXT:     `-CXXOperatorCallExpr {{.*}} <line:53:3, col:11> 'void' '-'
+// CHECK-NEXT:       |-ImplicitCastExpr {{.*}} <col:7> 'void (*)(E, E)' <FunctionToPointerDecay>
+// CHECK-NEXT:       | `-DeclRefExpr {{.*}} <col:7> 'void (E, E)' lvalue Function {{.*}} 'operator-' 'void (E, E)' (UsingShadow {{.*}} 'operator-')
+// CHECK-NEXT:       |-CXXScalarValueInitExpr {{.*}} <col:3, col:5> 'E'
+// CHECK-NEXT:       `-CXXScalarValueInitExpr {{.*}} <col:9, col:11> 'E'

clang/test/Index/annotate-operator-call-expr.cpp

void testFoo(Foo foo, int index) {
 
   foo[foo[index]];
   foo[foo() + foo[index]];
   foo[foo(index) + foo[index]];
 }
 
 // RUN: c-index-test -test-annotate-tokens=%s:7:1:7:100 %s -std=c++11 -Wno-unused-value | FileCheck %s -check-prefix=CHECK1
 // CHECK1: Identifier: "foo" [7:3 - 7:6] DeclRefExpr=foo:6:18
-// CHECK1: Punctuation: "(" [7:6 - 7:7] DeclRefExpr=operator():3:7 RefName=[7:6 - 7:7] RefName=[7:7 - 7:8]
-// CHECK1: Punctuation: ")" [7:7 - 7:8] DeclRefExpr=operator():3:7 RefName=[7:6 - 7:7] RefName=[7:7 - 7:8]
+// CHECK1: Punctuation: "(" [7:6 - 7:7] CallExpr=operator():3:7
+// CHECK1: Punctuation: ")" [7:7 - 7:8] CallExpr=operator():3:7
 // CHECK1: Punctuation: ";" [7:8 - 7:9] CompoundStmt=
 
 // RUN: c-index-test -test-annotate-tokens=%s:8:1:8:100 %s -std=c++11 -Wno-unused-value | FileCheck %s -check-prefix=CHECK2
-// CHECK2: Punctuation: "(" [8:6 - 8:7] DeclRefExpr=operator():3:7 RefName=[8:6 - 8:7] RefName=[8:12 - 8:13]
+// CHECK2: Punctuation: "(" [8:6 - 8:7] CallExpr=operator():3:7
 // CHECK2: Identifier: "index" [8:7 - 8:12] DeclRefExpr=index:6:27
-// CHECK2: Punctuation: ")" [8:12 - 8:13] DeclRefExpr=operator():3:7 RefName=[8:6 - 8:7] RefName=[8:12 - 8:13]
+// CHECK2: Punctuation: ")" [8:12 - 8:13] CallExpr=operator():3:7
 // CHECK2: Punctuation: ";" [8:13 - 8:14] CompoundStmt=
 
 // RUN: c-index-test -test-annotate-tokens=%s:10:1:10:100 %s -std=c++11 -Wno-unused-value | FileCheck %s -check-prefix=CHECK3
 // CHECK3: Identifier: "foo" [10:3 - 10:6] DeclRefExpr=foo:6:18
-// CHECK3: Punctuation: "[" [10:6 - 10:7] DeclRefExpr=operator[]:2:7 RefName=[10:6 - 10:7] RefName=[10:12 - 10:13]
+// CHECK3: Punctuation: "[" [10:6 - 10:7] CallExpr=operator[]:2:7
 // CHECK3: Identifier: "index" [10:7 - 10:12] DeclRefExpr=index:6:27
-// CHECK3: Punctuation: "]" [10:12 - 10:13] DeclRefExpr=operator[]:2:7 RefName=[10:6 - 10:7] RefName=[10:12 - 10:13]
+// CHECK3: Punctuation: "]" [10:12 - 10:13] CallExpr=operator[]:2:7
 // CHECK3: Punctuation: ";" [10:13 - 10:14] CompoundStmt=
 
 // RUN: c-index-test -test-annotate-tokens=%s:11:1:11:100 %s -std=c++11 -Wno-unused-value | FileCheck %s -check-prefix=CHECK4
 // CHECK4: Identifier: "foo" [11:3 - 11:6] DeclRefExpr=foo:6:18
-// CHECK4: Punctuation: "[" [11:6 - 11:7] DeclRefExpr=operator[]:2:7 RefName=[11:6 - 11:7] RefName=[11:20 - 11:21]
+// CHECK4: Punctuation: "[" [11:6 - 11:7] CallExpr=operator[]:2:7
 // CHECK4: Identifier: "index" [11:7 - 11:12] DeclRefExpr=index:6:27
 // CHECK4: Punctuation: "+" [11:13 - 11:14] BinaryOperator=
 // CHECK4: Identifier: "index" [11:15 - 11:20] DeclRefExpr=index:6:27
-// CHECK4: Punctuation: "]" [11:20 - 11:21] DeclRefExpr=operator[]:2:7 RefName=[11:6 - 11:7] RefName=[11:20 - 11:21]
+// CHECK4: Punctuation: "]" [11:20 - 11:21] CallExpr=operator[]:2:7
 // CHECK4: Punctuation: ";" [11:21 - 11:22] CompoundStmt=
 
 // RUN: c-index-test -test-annotate-tokens=%s:13:1:13:100 %s -std=c++11 -Wno-unused-value | FileCheck %s -check-prefix=CHECK5
 // CHECK5: Identifier: "foo" [13:3 - 13:6] DeclRefExpr=foo:6:18
-// CHECK5: Punctuation: "[" [13:6 - 13:7] DeclRefExpr=operator[]:2:7 RefName=[13:6 - 13:7] RefName=[13:17 - 13:18]
+// CHECK5: Punctuation: "[" [13:6 - 13:7] CallExpr=operator[]:2:7
 // CHECK5: Identifier: "foo" [13:7 - 13:10] DeclRefExpr=foo:6:18
-// CHECK5: Punctuation: "[" [13:10 - 13:11] DeclRefExpr=operator[]:2:7 RefName=[13:10 - 13:11] RefName=[13:16 - 13:17]
+// CHECK5: Punctuation: "[" [13:10 - 13:11] CallExpr=operator[]:2:7
 // CHECK5: Identifier: "index" [13:11 - 13:16] DeclRefExpr=index:6:27
-// CHECK5: Punctuation: "]" [13:16 - 13:17] DeclRefExpr=operator[]:2:7 RefName=[13:10 - 13:11] RefName=[13:16 - 13:17]
-// CHECK5: Punctuation: "]" [13:17 - 13:18] DeclRefExpr=operator[]:2:7 RefName=[13:6 - 13:7] RefName=[13:17 - 13:18]
+// CHECK5: Punctuation: "]" [13:16 - 13:17] CallExpr=operator[]:2:7
+// CHECK5: Punctuation: "]" [13:17 - 13:18] CallExpr=operator[]:2:7
 // CHECK5: Punctuation: ";" [13:18 - 13:19] CompoundStmt=
 
 // RUN: c-index-test -test-annotate-tokens=%s:14:1:14:100 %s -std=c++11 -Wno-unused-value | FileCheck %s -check-prefix=CHECK6
 // CHECK6: Identifier: "foo" [14:3 - 14:6] DeclRefExpr=foo:6:18
-// CHECK6: Punctuation: "[" [14:6 - 14:7] DeclRefExpr=operator[]:2:7 RefName=[14:6 - 14:7] RefName=[14:25 - 14:26]
+// CHECK6: Punctuation: "[" [14:6 - 14:7] CallExpr=operator[]:2:7
 // CHECK6: Identifier: "foo" [14:7 - 14:10] DeclRefExpr=foo:6:18
-// CHECK6: Punctuation: "(" [14:10 - 14:11] DeclRefExpr=operator():3:7 RefName=[14:10 - 14:11] RefName=[14:11 - 14:12]
-// CHECK6: Punctuation: ")" [14:11 - 14:12] DeclRefExpr=operator():3:7 RefName=[14:10 - 14:11] RefName=[14:11 - 14:12]
+// CHECK6: Punctuation: "(" [14:10 - 14:11] CallExpr=operator():3:7
+// CHECK6: Punctuation: ")" [14:11 - 14:12] CallExpr=operator():3:7
 // CHECK6: Punctuation: "+" [14:13 - 14:14] BinaryOperator=
 // CHECK6: Identifier: "foo" [14:15 - 14:18] DeclRefExpr=foo:6:18
-// CHECK6: Punctuation: "[" [14:18 - 14:19] DeclRefExpr=operator[]:2:7 RefName=[14:18 - 14:19] RefName=[14:24 - 14:25]
-// CHECK6: Identifier: "index" [14:19 - 14:24] DeclRefExpr=operator[]:2:7 RefName=[14:6 - 14:7] RefName=[14:25 - 14:26]
-// CHECK6: Punctuation: "]" [14:24 - 14:25] DeclRefExpr=operator[]:2:7 RefName=[14:18 - 14:19] RefName=[14:24 - 14:25]
-// CHECK6: Punctuation: "]" [14:25 - 14:26] DeclRefExpr=operator[]:2:7 RefName=[14:6 - 14:7] RefName=[14:25 - 14:26]
+// CHECK6: Punctuation: "[" [14:18 - 14:19] CallExpr=operator[]:2:7
+// CHECK6: Identifier: "index" [14:19 - 14:24] DeclRefExpr=index:6:27
+// CHECK6: Punctuation: "]" [14:24 - 14:25] CallExpr=operator[]:2:7
+// CHECK6: Punctuation: "]" [14:25 - 14:26] CallExpr=operator[]:2:7
 // CHECK6: Punctuation: ";" [14:26 - 14:27] CompoundStmt=
 
 // RUN: c-index-test -test-annotate-tokens=%s:15:1:15:100 %s -std=c++11 -Wno-unused-value | FileCheck %s -check-prefix=CHECK7
 // CHECK7: Identifier: "foo" [15:3 - 15:6] DeclRefExpr=foo:6:18
-// CHECK7: Punctuation: "[" [15:6 - 15:7] DeclRefExpr=operator[]:2:7 RefName=[15:6 - 15:7] RefName=[15:30 - 15:31]
+// CHECK7: Punctuation: "[" [15:6 - 15:7] CallExpr=operator[]:2:7
 // CHECK7: Identifier: "foo" [15:7 - 15:10] DeclRefExpr=foo:6:18
-// CHECK7: Punctuation: "(" [15:10 - 15:11] DeclRefExpr=operator():3:7 RefName=[15:10 - 15:11] RefName=[15:16 - 15:17]
+// CHECK7: Punctuation: "(" [15:10 - 15:11] CallExpr=operator():3:7
 // CHECK7: Identifier: "index" [15:11 - 15:16] DeclRefExpr=index:6:27
-// CHECK7: Punctuation: ")" [15:16 - 15:17] DeclRefExpr=operator():3:7 RefName=[15:10 - 15:11] RefName=[15:16 - 15:17]
+// CHECK7: Punctuation: ")" [15:16 - 15:17] CallExpr=operator():3:7
 // CHECK7: Punctuation: "+" [15:18 - 15:19] BinaryOperator=
 // CHECK7: Identifier: "foo" [15:20 - 15:23] DeclRefExpr=foo:6:18
-// CHECK7: Punctuation: "[" [15:23 - 15:24] DeclRefExpr=operator[]:2:7 RefName=[15:23 - 15:24] RefName=[15:29 - 15:30]
+// CHECK7: Punctuation: "[" [15:23 - 15:24] CallExpr=operator[]:2:7
 // CHECK7: Identifier: "index" [15:24 - 15:29] DeclRefExpr=index:6:27
-// CHECK7: Punctuation: "]" [15:29 - 15:30] DeclRefExpr=operator[]:2:7 RefName=[15:23 - 15:24] RefName=[15:29 - 15:30]
-// CHECK7: Punctuation: "]" [15:30 - 15:31] DeclRefExpr=operator[]:2:7 RefName=[15:6 - 15:7] RefName=[15:30 - 15:31]
+// CHECK7: Punctuation: "]" [15:29 - 15:30] CallExpr=operator[]:2:7
+// CHECK7: Punctuation: "]" [15:30 - 15:31] CallExpr=operator[]:2:7
 // CHECK7: Punctuation: ";" [15:31 - 15:32] CompoundStmt=
 

clang/test/Index/cursor-ref-names.cpp

 // RUN: c-index-test -test-load-source all %s | FileCheck %s
 // CHECK: cursor-ref-names.cpp:17:5: DeclStmt= Extent=[17:5 - 17:14]
 // CHECK: cursor-ref-names.cpp:17:9: VarDecl=inst:17:9 (Definition) Extent=[17:5 - 17:13]
 // CHECK: cursor-ref-names.cpp:17:5: TypeRef=struct Sub:7:8 Extent=[17:5 - 17:8]
 // CHECK: cursor-ref-names.cpp:17:9: CallExpr=Sub:7:8 Extent=[17:9 - 17:13]
 // CHECK: cursor-ref-names.cpp:18:5: CallExpr=func:8:10 Extent=[18:5 - 18:16]
 // CHECK: cursor-ref-names.cpp:18:10: MemberRefExpr=func:8:10 SingleRefName=[18:10 - 18:14] RefName=[18:10 - 18:14] Extent=[18:5 - 18:14]
 // CHECK: cursor-ref-names.cpp:18:5: DeclRefExpr=inst:17:9 Extent=[18:5 - 18:9]
-// CHECK: cursor-ref-names.cpp:19:5: CallExpr=operator[]:4:9 SingleRefName=[19:9 - 19:12] RefName=[19:9 - 19:10] RefName=[19:11 - 19:12] Extent=[19:5 - 19:12]
+// CHECK: cursor-ref-names.cpp:19:5: CallExpr=operator[]:4:9 Extent=[19:5 - 19:12] 
 // CHECK: cursor-ref-names.cpp:19:5: DeclRefExpr=inst:17:9 Extent=[19:5 - 19:9]
-// CHECK: cursor-ref-names.cpp:19:9: DeclRefExpr=operator[]:4:9 RefName=[19:9 - 19:10] RefName=[19:11 - 19:12] Extent=[19:9 - 19:12]
+// CHECK: cursor-ref-names.cpp:19:9: DeclRefExpr=operator[]:4:9 Extent=[19:9 - 19:10]
 // CHECK: cursor-ref-names.cpp:20:5: CallExpr=operator[]:4:9 Extent=[20:5 - 20:23]
 // CHECK: cursor-ref-names.cpp:20:10: MemberRefExpr=operator[]:4:9 SingleRefName=[20:10 - 20:20] RefName=[20:10 - 20:18] RefName=[20:18 - 20:19] RefName=[20:19 - 20:20] Extent=[20:5 - 20:20]
 // CHECK: cursor-ref-names.cpp:20:5: DeclRefExpr=inst:17:9 Extent=[20:5 - 20:9]
 // CHECK: cursor-ref-names.cpp:22:5: CallExpr=operator[]:4:9 Extent=[22:5 - 22:34]
 // CHECK: cursor-ref-names.cpp:22:21: MemberRefExpr=operator[]:4:9 SingleRefName=[22:10 - 22:31] RefName=[22:10 - 22:21] RefName=[22:21 - 22:29] RefName=[22:29 - 22:30] RefName=[22:30 - 22:31] Extent=[22:5 - 22:31]
 // CHECK: cursor-ref-names.cpp:22:5: DeclRefExpr=inst:17:9 Extent=[22:5 - 22:9]
 // CHECK: cursor-ref-names.cpp:22:10: TemplateRef=Base:2:8 Extent=[22:10 - 22:14]
 // CHECK: cursor-ref-names.cpp:23:5: CallExpr=myMax:12:10 Extent=[23:5 - 23:21]
 // CHECK: cursor-ref-names.cpp:23:5: DeclRefExpr=myMax:12:10 RefName=[23:5 - 23:10] RefName=[23:10 - 23:15] Extent=[23:5 - 23:15]

clang/unittests/ASTMatchers/ASTMatchersTraversalTest.cpp

 
 TEST(UsingDeclaration, ThroughUsingDeclaration) {
   EXPECT_TRUE(matches(
     "namespace a { void f(); } using a::f; void g() { f(); }",
     declRefExpr(throughUsingDecl(anything()))));
   EXPECT_TRUE(notMatches(
     "namespace a { void f(); } using a::f; void g() { a::f(); }",
     declRefExpr(throughUsingDecl(anything()))));
+  EXPECT_TRUE(matches("struct S {}; namespace a { int operator+(S s1, S s2); } "
+                      "using a::operator+; int g() { return S() + S(); }",
+                      declRefExpr(throughUsingDecl(anything()))));
 }
 
 TEST(SingleDecl, IsSingleDecl) {
   StatementMatcher SingleDeclStmt =
     declStmt(hasSingleDecl(varDecl(hasInitializer(anything()))));
   EXPECT_TRUE(matches("void f() {int a = 4;}", SingleDeclStmt));
   EXPECT_TRUE(notMatches("void f() {int a;}", SingleDeclStmt));
   EXPECT_TRUE(notMatches("void f() {int a = 4, b = 3;}",