[PATCH] D48955: [libc++] Improve diagnostics for non-const comparators and hashers in associative containers

[Louis Dionne via Phabricator via llvm-commits]

ldionne added a comment.

Before the patch, the backtrace refers to the instantiation of the set's destructor instead of referring to the set's instantiation itself:

BEFORE (ordered associative containers)
=======================================

  In file included from /Users/ldionne/work/llvm/libcxx/test/libcxx/containers/associative/non_const_comparator.fail.cpp:16:
  In file included from /Users/ldionne/work/llvm/libcxx/include/set:389:
  /Users/ldionne/work/llvm/libcxx/include/__tree:1812:22: warning: the specified comparator type does not provide a const call operator [-Wuser-defined-warnings]
                       __trigger_diagnostics()), "");
                       ^
  /Users/ldionne/work/llvm/libcxx/include/set:400:28: note: in instantiation of member function 'std::__1::__tree<int, BadCompare, std::__1::allocator<int> >::~__tree' requested here
  class _LIBCPP_TEMPLATE_VIS set
                             ^
  /Users/ldionne/work/llvm/libcxx/include/__tree:963:7: note: from 'diagnose_if' attribute on '__trigger_diagnostics':
        _LIBCPP_DIAGNOSE_WARNING(!__invokable<_Compare const&, _Tp const&, _Tp const&>::value,
        ^                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /Users/ldionne/work/llvm/libcxx/include/__config:1165:21: note: expanded from macro '_LIBCPP_DIAGNOSE_WARNING'
       __attribute__((diagnose_if(__VA_ARGS__, "warning")))
                      ^           ~~~~~~~~~~~



AFTER (ordered associative containers)
======================================

  In file included from /Users/ldionne/work/llvm/libcxx/test/libcxx/containers/associative/non_const_comparator.fail.cpp:16:
  /Users/ldionne/work/llvm/libcxx/include/set:412:26: warning: the specified comparator type does not provide a const call operator [-Wuser-defined-warnings]
      static_assert(sizeof(__diagnose_non_const_comparator<_Key, _Compare>()), "");
                           ^
  /Users/ldionne/work/llvm/libcxx/test/libcxx/containers/associative/non_const_comparator.fail.cpp:34:7: note: in instantiation of template class 'std::__1::set<int, BadCompare, std::__1::allocator<int> >' requested here
      C s;
        ^
  /Users/ldionne/work/llvm/libcxx/include/__tree:957:5: note: from 'diagnose_if' attribute on '__diagnose_non_const_comparator<int, BadCompare>':
      _LIBCPP_DIAGNOSE_WARNING(!std::__invokable<_Compare const&, _Tp const&, _Tp const&>::value,
      ^                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /Users/ldionne/work/llvm/libcxx/include/__config:1165:21: note: expanded from macro '_LIBCPP_DIAGNOSE_WARNING'
       __attribute__((diagnose_if(__VA_ARGS__, "warning")))
                      ^           ~~~~~~~~~~~

For unordered containers, the difference is that we don't show __hash_table in the backtrace anymore:

BEFORE (unordered associative containers)
=========================================

  In file included from /Users/ldionne/work/llvm/libcxx/test/libcxx/containers/unord/non_const_comparator.fail.cpp:16:
  In file included from /Users/ldionne/work/llvm/libcxx/include/unordered_set:323:
  /Users/ldionne/work/llvm/libcxx/include/__hash_table:956:77: warning: the specified hash functor does not provide a const call operator [-Wuser-defined-warnings]
      static_assert(__diagnose_hash_table_helper<_Tp, _Hash, _Equal, _Alloc>::__trigger_diagnostics(), "");
                                                                              ^
  /Users/ldionne/work/llvm/libcxx/include/unordered_set:353:13: note: in instantiation of template class 'std::__1::__hash_table<int, BadHash, BadEqual, std::__1::allocator<int> >' requested here
      __table __table_;
              ^
  /Users/ldionne/work/llvm/libcxx/test/libcxx/containers/unord/non_const_comparator.fail.cpp:42:7: note: in instantiation of template class 'std::__1::unordered_set<int, BadHash, BadEqual, std::__1::allocator<int> >' requested here
      C s;
        ^
  /Users/ldionne/work/llvm/libcxx/include/__hash_table:867:5: note: from 'diagnose_if' attribute on '__trigger_diagnostics':
      _LIBCPP_DIAGNOSE_WARNING(__check_hash_requirements<_Key, _Hash>::value
      ^                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /Users/ldionne/work/llvm/libcxx/include/__config:1165:21: note: expanded from macro '_LIBCPP_DIAGNOSE_WARNING'
       __attribute__((diagnose_if(__VA_ARGS__, "warning")))
                      ^           ~~~~~~~~~~~



AFTER (unordered associative containers)
========================================

  In file included from /Users/ldionne/work/llvm/libcxx/test/libcxx/containers/unord/non_const_comparator.fail.cpp:16:
  /Users/ldionne/work/llvm/libcxx/include/unordered_set:349:26: warning: the specified hash functor does not provide a const call operator [-Wuser-defined-warnings]
      static_assert(sizeof(__diagnose_unordered_container_requirements<_Value, _Hash, _Pred>(0)), "");
                           ^
  /Users/ldionne/work/llvm/libcxx/test/libcxx/containers/unord/non_const_comparator.fail.cpp:44:7: note: in instantiation of template class 'std::__1::unordered_set<int, BadHash, BadEqual, std::__1::allocator<int> >' requested here
      C s;
        ^
  /Users/ldionne/work/llvm/libcxx/include/__hash_table:868:5: note: from 'diagnose_if' attribute on '__diagnose_unordered_container_requirements<int, BadHash, BadEqual>':
      _LIBCPP_DIAGNOSE_WARNING(!__invokable<_Hash const&, _Key const&>::value,
      ^                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  /Users/ldionne/work/llvm/libcxx/include/__config:1165:21: note: expanded from macro '_LIBCPP_DIAGNOSE_WARNING'
       __attribute__((diagnose_if(__VA_ARGS__, "warning")))
                      ^           ~~~~~~~~~~~


Repository:
  rL LLVM

https://reviews.llvm.org/D48955