[llvm] [ADT] Add a unittest for the ScopedHashTable class (PR #120183)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-rhel` running on `ppc64le-clang-rhel-test` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/145/builds/3933

<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 (4.4s)
-- Generating done (0.2s)
-- Build files have been written to: /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/runtimes/runtimes-bins
21.455 [291/48/864] cd /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/clang/bindings/python && /home/buildbots/llvm-external-buildbots/cmake-3.28.2/bin/cmake -E env CLANG_NO_DEFAULT_CONFIG=1 CLANG_LIBRARY_PATH=/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/lib /home/buildbots/llvm-external-buildbots/workers/env/bin/python3.8 -m unittest discover
......................................................................................................................................................
----------------------------------------------------------------------
Ran 150 tests in 2.967s

OK
22.460 [115/48/1040] Building CXX object unittests/ADT/CMakeFiles/ADTTests.dir/ScopedHashTableTest.cpp.o
FAILED: unittests/ADT/CMakeFiles/ADTTests.dir/ScopedHashTableTest.cpp.o 
ccache /home/docker/llvm-external-buildbots/clang.17.0.6/bin/clang++ --gcc-toolchain=/gcc-toolchain/usr -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/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/unittests/ADT -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/build/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/third-party/unittest/googletest/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/third-party/unittest/googlemock/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror -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 -std=c++17  -Wno-variadic-macros -Wno-gnu-zero-variadic-macro-arguments -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -Wno-suggest-override -MD -MT unittests/ADT/CMakeFiles/ADTTests.dir/ScopedHashTableTest.cpp.o -MF unittests/ADT/CMakeFiles/ADTTests.dir/ScopedHashTableTest.cpp.o.d -o unittests/ADT/CMakeFiles/ADTTests.dir/ScopedHashTableTest.cpp.o -c /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT/ScopedHashTableTest.cpp
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT/ScopedHashTableTest.cpp:41:20: error: 'ScopedHashTableScope' may not intend to support class template argument deduction [-Werror,-Wctad-maybe-unsupported]
   41 |   [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
      |                    ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include/llvm/ADT/ScopedHashTable.h:85:7: note: add a deduction guide to suppress this warning
   85 | class ScopedHashTableScope {
      |       ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT/ScopedHashTableTest.cpp:46:20: error: 'ScopedHashTableScope' may not intend to support class template argument deduction [-Werror,-Wctad-maybe-unsupported]
   46 |   [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
      |                    ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include/llvm/ADT/ScopedHashTable.h:85:7: note: add a deduction guide to suppress this warning
   85 | class ScopedHashTableScope {
      |       ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT/ScopedHashTableTest.cpp:52:20: error: 'ScopedHashTableScope' may not intend to support class template argument deduction [-Werror,-Wctad-maybe-unsupported]
   52 |   [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
      |                    ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include/llvm/ADT/ScopedHashTable.h:85:7: note: add a deduction guide to suppress this warning
   85 | class ScopedHashTableScope {
      |       ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT/ScopedHashTableTest.cpp:53:20: error: 'ScopedHashTableScope' may not intend to support class template argument deduction [-Werror,-Wctad-maybe-unsupported]
   53 |   [[maybe_unused]] ScopedHashTableScope varScope2(symbolTable);
      |                    ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include/llvm/ADT/ScopedHashTable.h:85:7: note: add a deduction guide to suppress this warning
   85 | class ScopedHashTableScope {
      |       ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT/ScopedHashTableTest.cpp:54:20: error: 'ScopedHashTableScope' may not intend to support class template argument deduction [-Werror,-Wctad-maybe-unsupported]
   54 |   [[maybe_unused]] ScopedHashTableScope varScope3(symbolTable);
      |                    ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include/llvm/ADT/ScopedHashTable.h:85:7: note: add a deduction guide to suppress this warning
   85 | class ScopedHashTableScope {
      |       ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT/ScopedHashTableTest.cpp:61:22: error: 'ScopedHashTableScope' may not intend to support class template argument deduction [-Werror,-Wctad-maybe-unsupported]
   61 |     [[maybe_unused]] ScopedHashTableScope varScope(symbolTable);
      |                      ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/include/llvm/ADT/ScopedHashTable.h:85:7: note: add a deduction guide to suppress this warning
   85 | class ScopedHashTableScope {
      |       ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-rhel-test/clang-ppc64le-rhel/llvm-project/llvm/unittests/ADT/ScopedHashTableTest.cpp:68:20: error: 'ScopedHashTableScope' may not intend to support class template argument deduction [-Werror,-Wctad-maybe-unsupported]

```

</details>

https://github.com/llvm/llvm-project/pull/120183