[llvm] Support: Add vfs::OutputBackend and OutputFile to virtualize compiler outputs (PR #113363)

Fri Sep 5 11:05:16 PDT 2025

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-ppc64le-linux-test-suite` running on `ppc64le-clang-test-suite` while building `llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/95/builds/17944

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
...
20.203 [5/4/77] Generating POWERPC64LELinuxConfig/Asan-powerpc64le-calls-Noinst-Test
20.543 [5/3/78] Generating ASAN_NOINST_TEST_OBJECTS.gtest-all.cc.powerpc64le-inline.o
20.740 [4/3/79] Generating POWERPC64LELinuxConfig/Asan-powerpc64le-inline-Noinst-Test
23.028 [4/2/80] Generating ASAN_INST_TEST_OBJECTS.gtest-all.cc.powerpc64le-calls.o
23.275 [2/3/81] Generating POWERPC64LELinuxDynamicConfig/Asan-powerpc64le-calls-Dynamic-Test
23.464 [2/2/82] Generating POWERPC64LELinuxConfig/Asan-powerpc64le-calls-Test
26.517 [2/1/83] Generating ASAN_INST_TEST_OBJECTS.gtest-all.cc.powerpc64le-inline.o
26.763 [0/2/84] Generating POWERPC64LELinuxDynamicConfig/Asan-powerpc64le-inline-Dynamic-Test
26.952 [0/1/85] Generating POWERPC64LELinuxConfig/Asan-powerpc64le-inline-Test
8.890 [4/54/1190] Building CXX object unittests/Support/CMakeFiles/SupportTests.dir/VirtualOutputConfigTest.cpp.o
FAILED: unittests/Support/CMakeFiles/SupportTests.dir/VirtualOutputConfigTest.cpp.o 
ccache /usr/lib64/ccache/c++ -DGTEST_HAS_RTTI=0 -DLLVM_BUILD_STATIC -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GLIBCXX_USE_CXX11_ABI=1 -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/unittests/Support -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/unittests/Support -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include -I/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googlemock/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-uninitialized -Wno-nonnull -Wno-class-memaccess -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -std=c++17  -Wno-dangling-else -Wno-variadic-macros -fno-exceptions -funwind-tables -fno-rtti -UNDEBUG -Wno-suggest-override -MD -MT unittests/Support/CMakeFiles/SupportTests.dir/VirtualOutputConfigTest.cpp.o -MF unittests/Support/CMakeFiles/SupportTests.dir/VirtualOutputConfigTest.cpp.o.d -o unittests/Support/CMakeFiles/SupportTests.dir/VirtualOutputConfigTest.cpp.o -c /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/unittests/Support/VirtualOutputConfigTest.cpp
In file included from /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include/gtest/gtest-printers.h:122,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include/gtest/gtest-matchers.h:49,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include/gtest/internal/gtest-death-test-internal.h:47,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include/gtest/gtest-death-test.h:43,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:65,
                 from /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/unittests/Support/VirtualOutputConfigTest.cpp:11:
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/unittests/Support/VirtualOutputConfigTest.cpp: In member function ‘virtual void {anonymous}::VirtualOutputConfigTest_equals_Test::TestBody()’:
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/unittests/Support/VirtualOutputConfigTest.cpp:72:3:   in ‘constexpr’ expansion of ‘llvm::vfs::OutputConfig().llvm::vfs::OutputConfig::operator==(llvm::vfs::OutputConfig())’
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include/gtest/internal/gtest-internal.h:1493:48: internal compiler error: in cxx_eval_bit_field_ref, at cp/constexpr.c:2683
           ::testing::AssertionResult(expression))                     \
                                                ^
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:1792:3: note: in expansion of macro ‘GTEST_TEST_BOOLEAN_’
   GTEST_TEST_BOOLEAN_(condition, #condition, false, true, \
   ^~~~~~~~~~~~~~~~~~~
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/third-party/unittest/googletest/include/gtest/gtest.h:1807:32: note: in expansion of macro ‘GTEST_EXPECT_TRUE’
 #define EXPECT_TRUE(condition) GTEST_EXPECT_TRUE(condition)
                                ^~~~~~~~~~~~~~~~~
/home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/llvm/unittests/Support/VirtualOutputConfigTest.cpp:72:3: note: in expansion of macro ‘EXPECT_TRUE’
   EXPECT_TRUE(OutputConfig() == OutputConfig());
   ^~~~~~~~~~~
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://bugzilla.redhat.com/bugzilla> for instructions.
Preprocessed source stored into /tmp/ccjDyzCu.out file, please attach this to your bugreport.
30.353 [4/6/1238] Linking CXX executable unittests/DebugInfo/LogicalView/DebugInfoLogicalViewTests
34.843 [4/4/1240] Linking CXX executable tools/clang/unittests/Interpreter/ExceptionTests/ClangReplInterpreterExceptionTests
36.455 [4/3/1241] Linking CXX executable tools/clang/unittests/Interpreter/ClangReplInterpreterTests
48.260 [4/2/1242] Linking CXX executable tools/clang/tools/extra/clangd/unittests/ClangdTests
48.822 [4/1/1243] Linking CXX executable tools/clang/unittests/AllClangUnitTests
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/113363