[llvm] [EquivClasses] Introduce members iterator-helper (PR #130139)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `premerge-monolithic-linux` running on `premerge-linux-1` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/153/builds/25023

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
...
-- Configuring done
-- Generating done
-- Build files have been written to: /build/buildbot/premerge-monolithic-linux/build/runtimes/runtimes-bins
3.057 [102/58/69] cd /build/buildbot/premerge-monolithic-linux/llvm-project/clang/bindings/python && /etc/cmake/bin/cmake -E env CLANG_NO_DEFAULT_CONFIG=1 CLANG_LIBRARY_PATH=/build/buildbot/premerge-monolithic-linux/build/lib /usr/bin/python3.10 -m unittest discover
..........................................................................................................................................................
----------------------------------------------------------------------
Ran 154 tests in 2.145s

OK
6.051 [56/58/110] Building CXX object unittests/ADT/CMakeFiles/ADTTests.dir/EquivalenceClassesTest.cpp.o
FAILED: unittests/ADT/CMakeFiles/ADTTests.dir/EquivalenceClassesTest.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes /usr/bin/ccache /usr/bin/clang++ -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/build/buildbot/premerge-monolithic-linux/build/unittests/ADT -I/build/buildbot/premerge-monolithic-linux/llvm-project/llvm/unittests/ADT -I/build/buildbot/premerge-monolithic-linux/build/include -I/build/buildbot/premerge-monolithic-linux/llvm-project/llvm/include -I/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googletest/include -I/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include -gmlt -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG  -Wno-variadic-macros -Wno-gnu-zero-variadic-macro-arguments -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -Wno-suggest-override -std=c++17 -MD -MT unittests/ADT/CMakeFiles/ADTTests.dir/EquivalenceClassesTest.cpp.o -MF unittests/ADT/CMakeFiles/ADTTests.dir/EquivalenceClassesTest.cpp.o.d -o unittests/ADT/CMakeFiles/ADTTests.dir/EquivalenceClassesTest.cpp.o -c /build/buildbot/premerge-monolithic-linux/llvm-project/llvm/unittests/ADT/EquivalenceClassesTest.cpp
In file included from /build/buildbot/premerge-monolithic-linux/llvm-project/llvm/unittests/ADT/EquivalenceClassesTest.cpp:10:
In file included from /build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include/gmock/gmock.h:61:
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include/gmock/gmock-more-matchers.h:73:40: error: no member named 'size' in 'llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator>'
    *listener << "whose size is " << c.size();
                                     ~ ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googletest/include/gtest/gtest-matchers.h:647:20: note: in instantiation of function template specialization 'testing::internal::IsEmptyMatcher::MatchAndExplain<llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator>>' requested here
      return impl_.MatchAndExplain(x, listener);
                   ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googletest/include/gtest/gtest-matchers.h:638:14: note: in instantiation of member function 'testing::PolymorphicMatcher<testing::internal::IsEmptyMatcher>::MonomorphicImpl<const llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator> &>::MatchAndExplain' requested here
    explicit MonomorphicImpl(const Impl& impl) : impl_(impl) {}
             ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googletest/include/gtest/gtest-matchers.h:631:27: note: in instantiation of member function 'testing::PolymorphicMatcher<testing::internal::IsEmptyMatcher>::MonomorphicImpl<const llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator> &>::MonomorphicImpl' requested here
    return Matcher<T>(new MonomorphicImpl<const T&>(impl_));
                          ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include/gmock/gmock-matchers.h:373:12: note: in instantiation of function template specialization 'testing::PolymorphicMatcher<testing::internal::IsEmptyMatcher>::operator Matcher<const llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator> &>' requested here
    return polymorphic_matcher_or_value;
           ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include/gmock/gmock-matchers.h:355:12: note: in instantiation of function template specialization 'testing::internal::MatcherCastImpl<const llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator> &, testing::PolymorphicMatcher<testing::internal::IsEmptyMatcher>>::CastImpl<false>' requested here
    return CastImpl(polymorphic_matcher_or_value,
           ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include/gmock/gmock-matchers.h:515:43: note: in instantiation of member function 'testing::internal::MatcherCastImpl<const llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator> &, testing::PolymorphicMatcher<testing::internal::IsEmptyMatcher>>::Cast' requested here
  return internal::MatcherCastImpl<T, M>::Cast(matcher);
                                          ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include/gmock/gmock-matchers.h:522:10: note: in instantiation of function template specialization 'testing::MatcherCast<const llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator> &, testing::PolymorphicMatcher<testing::internal::IsEmptyMatcher>>' requested here
  return MatcherCast<T>(polymorphic_matcher_or_value);
         ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include/gmock/gmock-matchers.h:1591:39: note: in instantiation of function template specialization 'testing::SafeMatcherCast<const llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator> &, testing::PolymorphicMatcher<testing::internal::IsEmptyMatcher>>' requested here
    const Matcher<const T&> matcher = SafeMatcherCast<const T&>(matcher_);
                                      ^
/build/buildbot/premerge-monolithic-linux/llvm-project/llvm/unittests/ADT/EquivalenceClassesTest.cpp:80:3: note: in instantiation of function template specialization 'testing::internal::PredicateFormatterFromMatcher<testing::PolymorphicMatcher<testing::internal::IsEmptyMatcher>>::operator()<llvm::iterator_range<llvm::EquivalenceClasses<int>::member_iterator>>' requested here
  EXPECT_THAT(EC.members(EC.end()), testing::IsEmpty());
  ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googlemock/include/gmock/gmock-matchers.h:5495:3: note: expanded from macro 'EXPECT_THAT'
  EXPECT_PRED_FORMAT1(              \
  ^
/build/buildbot/premerge-monolithic-linux/llvm-project/third-party/unittest/googletest/include/gtest/gtest_pred_impl.h:109:3: note: expanded from macro 'EXPECT_PRED_FORMAT1'
  GTEST_PRED_FORMAT1_(pred_format, v1, GTEST_NONFATAL_FAILURE_)

```

</details>

https://github.com/llvm/llvm-project/pull/130139