[flang-commits] [flang] [llvm] [llvm][flang] Silence warning, resume -Werror builds of flang (PR #175053)

Mon Jan 12 17:05:56 PST 2026

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `flang-runtime-cuda-clang` running on `as-builder-7` while building `flang,llvm` at step 6 "build-default".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/7/builds/18595

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

```
Step 6 (build-default) failure: cmake (failure)
...
768.791 [302/12/7190] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/IterationSpace.cpp.o
778.735 [301/12/7191] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/MultiImageFortran.cpp.o
779.448 [300/12/7192] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/HostAssociations.cpp.o
781.124 [299/12/7193] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/IO.cpp.o
782.464 [298/12/7194] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/Mangler.cpp.o
783.857 [297/12/7195] Building CXX object tools/flang/lib/Evaluate/CMakeFiles/FortranEvaluate.dir/tools.cpp.o
807.607 [296/12/7196] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/OpenMP/Atomic.cpp.o
811.731 [295/12/7197] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/Runtime.cpp.o
812.173 [294/12/7198] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/Support/PrivateReductionUtils.cpp.o
817.267 [293/12/7199] Building CXX object tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/ConvertExpr.cpp.o
FAILED: tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/ConvertExpr.cpp.o 
CCACHE_CPP2=yes CCACHE_HASHDIR=yes CCACHE_SLOPPINESS=pch_defines,time_macros /usr/bin/ccache /usr/bin/c++ -DFLANG_INCLUDE_TESTS=1 -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/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/build/tools/flang/lib/Lower -I/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/lib/Lower -I/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include -I/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/build/tools/flang/include -I/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/build/include -I/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/llvm/include -isystem /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/../mlir/include -isystem /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/build/tools/mlir/include -isystem /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/build/tools/clang/include -isystem /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/llvm/../clang/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-dangling-reference -Wno-redundant-move -Wno-pessimizing-move -Wno-array-bounds -Wno-stringop-overread -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wsuggest-override -Wno-comment -Wno-misleading-indentation -Wctad-maybe-unsupported -fdiagnostics-color -ffunction-sections -fdata-sections -Werror -Wno-deprecated-copy -Wno-ctad-maybe-unsupported -fno-semantic-interposition -fpch-preprocess -O3 -DNDEBUG -std=c++17 -UNDEBUG -fno-exceptions -funwind-tables -fno-rtti -Winvalid-pch -include /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/build/tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/cmake_pch.hxx -MD -MT tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/ConvertExpr.cpp.o -MF tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/ConvertExpr.cpp.o.d -o tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/ConvertExpr.cpp.o -c /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/lib/Lower/ConvertExpr.cpp
In file included from /usr/include/c++/13/string_view:40,
                 from /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Common/enum-class.h:22,
                 from /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Common/idioms.h:26,
                 from /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Common/indirection.h:23,
                 from /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Lower/Support/Utils.h:16,
                 from /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Lower/ConvertExpr.h:20,
                 from /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/build/tools/flang/lib/Lower/CMakeFiles/FortranLower.dir/cmake_pch.hxx:5,
                 from <command-line>:
In static member function ‘static std::char_traits<char>::char_type* std::char_traits<char>::copy(char_type*, const char_type*, std::size_t)’,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/13/bits/basic_string.h:683:23,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&) [with _CharT = char; _Traits = char_traits<char>; _Alloc = allocator<char>]’ at /usr/include/c++/13/bits/basic_string.h:3676:46,
    inlined from ‘void Fortran::semantics::DumpEvaluateExpr::Show(const Fortran::evaluate::Expr<RESULT>&) [with T = Fortran::evaluate::SomeKind<Fortran::common::TypeCategory::Complex>]’ at /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Semantics/dump-expr.h:206:11:
/usr/include/c++/13/bits/char_traits.h:435:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ writing 74 bytes into a region of size 16 overflows the destination [-Werror=stringop-overflow=]
  435 |         return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
      |                                        ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
In file included from /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/lib/Lower/ConvertExpr.cpp:49:
/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Semantics/dump-expr.h: In member function ‘void Fortran::semantics::DumpEvaluateExpr::Show(const Fortran::evaluate::Expr<RESULT>&) [with T = Fortran::evaluate::SomeKind<Fortran::common::TypeCategory::Complex>]’:
/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Semantics/dump-expr.h:206:21: note: at offset 16 into destination object ‘<anonymous>’ of size 32
  206 |     Indent("expr <" + std::string(TypeOf<T>::name) + ">");
      |            ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In static member function ‘static std::char_traits<char>::char_type* std::char_traits<char>::copy(char_type*, const char_type*, std::size_t)’,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/13/bits/basic_string.h:683:23,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const _CharT*) [with _CharT = char; _Traits = char_traits<char>; _Alloc = allocator<char>]’ at /usr/include/c++/13/bits/basic_string.h:3690:43,
    inlined from ‘void Fortran::semantics::DumpEvaluateExpr::Show(const Fortran::evaluate::Expr<RESULT>&) [with T = Fortran::evaluate::SomeKind<Fortran::common::TypeCategory::Complex>]’ at /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Semantics/dump-expr.h:206:11:
/usr/include/c++/13/bits/char_traits.h:435:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ writing 75 bytes into a region of size 16 overflows the destination [-Werror=stringop-overflow=]
  435 |         return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));
      |                                        ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Semantics/dump-expr.h: In member function ‘void Fortran::semantics::DumpEvaluateExpr::Show(const Fortran::evaluate::Expr<RESULT>&) [with T = Fortran::evaluate::SomeKind<Fortran::common::TypeCategory::Complex>]’:
/home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Semantics/dump-expr.h:206:52: note: at offset 16 into destination object ‘<anonymous>’ of size 32
  206 |     Indent("expr <" + std::string(TypeOf<T>::name) + ">");
      |            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~
In static member function ‘static std::char_traits<char>::char_type* std::char_traits<char>::copy(char_type*, const char_type*, std::size_t)’,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::basic_string(std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&&) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/13/bits/basic_string.h:683:23,
    inlined from ‘std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&) [with _CharT = char; _Traits = char_traits<char>; _Alloc = allocator<char>]’ at /usr/include/c++/13/bits/basic_string.h:3676:46,
    inlined from ‘void Fortran::semantics::DumpEvaluateExpr::Show(const Fortran::evaluate::Expr<RESULT>&) [with T = Fortran::evaluate::SomeKind<Fortran::common::TypeCategory::Real>]’ at /home/buildbot/worker/as-builder-7/flang-runtime-cuda-clang/llvm-project/flang/include/flang/Semantics/dump-expr.h:206:11:
/usr/include/c++/13/bits/char_traits.h:435:56: error: ‘void* __builtin_memcpy(void*, const void*, long unsigned int)’ writing 71 bytes into a region of size 16 overflows the destination [-Werror=stringop-overflow=]
  435 |         return static_cast<char_type*>(__builtin_memcpy(__s1, __s2, __n));

```

</details>

https://github.com/llvm/llvm-project/pull/175053