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Building Flang with Visual C++ [2022/10]
Note: I wrote this in October 2022 but never got around to posting it. Doing so now to enable comparisons with the latest sources and compilers.
In Failing to Build Flang with Visual C++, the C++ compiler had bugs that prevented compilation from succeeding. I just tried a new version of the Visual C++ compiler (Microsoft (R) C/C++ Optimizing Compiler Version 19.34.31823.3 for x64). This failed to build the same commit with the following error.
D:\dev\repos\llvm-project\flang\lib\Evaluate\fold-implementation.h(1585): error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\flang\lib\Evaluate\fold-implementation.h(1585): warning C4189: 'ctx': local variable is initialized but not referenced
...This line was last modified by [flang][msvc] Fix lambda capture ambiguity. NFC. · llvm/llvm-project@0b671a4 (github.com). Can the entire workaround be removed? Some of it was introduced by [flang][msvc] Rework a MSVC work-around to avoid clang warning · llvm/llvm-project@75a5ec1 (github.com). I get the same warning as error if I rename ctx to context. I undo the MSVC workaround and get this error now:
D:\dev\repos\llvm-project\flang\lib\Evaluate\fold-implementation.h(1578): error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\flang\lib\Evaluate\fold-implementation.h(1578): warning C4101: 'buffer': unreferenced local variable
...Moving that variable deeper into the if-statement addresses that issue. I end up having to suppress C4661 again.
D:\dev\repos\llvm-project\flang\include\flang\Evaluate\expression.h(101): error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\flang\include\flang\Evaluate\expression.h(101): warning C4661: 'std::optional<Fortran::evaluate::DynamicType> Fortran::evaluate::ExpressionBase<Fortran::evaluate::SomeDerived>::GetType(void) const': no suitable definition provided for explicit template instantiation request
...These are the next failures I run into:
C:\PROGRA~1\MIB055~1\2022\Preview\VC\Tools\MSVC\1434~1.318\bin\Hostx64\x64\cl.exe /nologo /TP -DFLANG_LITTLE_ENDIAN=1 -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\include -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\include -ID:\dev\repos\llvm-project\build-nowarn\include -ID:\dev\repos\llvm-project\llvm\include -external:ID:\dev\repos\llvm-project\llvm\..\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\clang\include -external:ID:\dev\repos\llvm-project\llvm\..\clang\include -external:W0 /DWIN32 /D_WINDOWS /Zc:inline /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd4661 -wd4324 -w14062 -we4238 /Gw /WX /MD /O2 /Ob2 /EHs-c- /GR- -UNDEBUG -std:c++17 /showIncludes /Fotools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\mod-file.cpp.obj /Fdtools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\ /FS -c D:\dev\repos\llvm-project\flang\lib\Semantics\mod-file.cpp
D:\dev\repos\llvm-project\flang\lib\Semantics\mod-file.cpp(962): error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\flang\lib\Semantics\mod-file.cpp(962): warning C4834: discarding return value of function with 'nodiscard' attributec++ – What’s the reason for not using C++17’s [[nodiscard]] almost everywhere in new code? – Software Engineering Stack Exchange has a link to the proposal of [[nodiscard]] and other attributes. This is easy to resolve by casting the result to (void) as per Compiler warning (Level 1) C4834 | Microsoft Docs.
[4578/5288] Building CXX object tools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\expression.cpp.obj
C:\PROGRA~1\MIB055~1\2022\Preview\VC\Tools\MSVC\1434~1.318\bin\Hostx64\x64\cl.exe /nologo /TP -DFLANG_LITTLE_ENDIAN=1 -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\include -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\include -ID:\dev\repos\llvm-project\build-nowarn\include -ID:\dev\repos\llvm-project\llvm\include -external:ID:\dev\repos\llvm-project\llvm\..\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\clang\include -external:ID:\dev\repos\llvm-project\llvm\..\clang\include -external:W0 /DWIN32 /D_WINDOWS /Zc:inline /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd4661 -wd4324 -w14062 -we4238 /Gw /WX /MD /O2 /Ob2 /EHs-c- /GR- -UNDEBUG -std:c++17 /showIncludes /Fotools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\expression.cpp.obj /Fdtools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\ /FS -c D:\dev\repos\llvm-project\flang\lib\Semantics\expression.cpp
D:\dev\repos\llvm-project\flang\lib\Semantics\expression.cpp(1192): error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\flang\lib\Semantics\expression.cpp(1192): warning C4927: illegal conversion; more than one user-defined conversion has been implicitly applied
D:\dev\repos\llvm-project\flang\lib\Semantics\expression.cpp(1192): note: while calling the constructor 'Fortran::semantics::Symbol::Symbol(const Fortran::semantics::Symbol &) noexcept(false)'
D:\dev\repos\llvm-project\flang\include\flang\Semantics\symbol.h(734): note: compiler has generated 'Fortran::semantics::Symbol::Symbol' here
C:\PROGRA~1\MIB055~1\2022\Preview\VC\Tools\MSVC\1434~1.318\bin\Hostx64\x64\cl.exe /nologo /TP -DFLANG_LITTLE_ENDIAN=1 -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\include -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\include -ID:\dev\repos\llvm-project\build-nowarn\include -ID:\dev\repos\llvm-project\llvm\include -external:ID:\dev\repos\llvm-project\llvm\..\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\clang\include -external:ID:\dev\repos\llvm-project\llvm\..\clang\include -external:W0 /DWIN32 /D_WINDOWS /Zc:inline /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd4661 -wd4324 -w14062 -we4238 /Gw /WX /MD /O2 /Ob2 /EHs-c- /GR- -UNDEBUG -std:c++17 /showIncludes /Fotools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\resolve-names.cpp.obj /Fdtools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\ /FS -c D:\dev\repos\llvm-project\flang\lib\Semantics\resolve-names.cpp
D:\dev\repos\llvm-project\flang\lib\Semantics\resolve-names.cpp(3151): error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\flang\lib\Semantics\resolve-names.cpp(3151): warning C4927: illegal conversion; more than one user-defined conversion has been implicitly applied
D:\dev\repos\llvm-project\flang\lib\Semantics\resolve-names.cpp(3151): note: while calling the constructor 'Fortran::semantics::Symbol::Symbol(const Fortran::semantics::Symbol &) noexcept(false)'
D:\dev\repos\llvm-project\flang\include\flang\Semantics\symbol.h(734): note: compiler has generated 'Fortran::semantics::Symbol::Symbol' hereThis same warning appears in more files:
C:\PROGRA~1\MIB055~1\2022\Preview\VC\Tools\MSVC\1434~1.318\bin\Hostx64\x64\cl.exe /nologo /TP -DFLANG_LITTLE_ENDIAN=1 -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\include -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\include -ID:\dev\repos\llvm-project\build-nowarn\include -ID:\dev\repos\llvm-project\llvm\include -external:ID:\dev\repos\llvm-project\llvm\..\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\clang\include -external:ID:\dev\repos\llvm-project\llvm\..\clang\include -external:W0 /DWIN32 /D_WINDOWS /Zc:inline /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd4661 -wd4324 -w14062 -we4238 /Gw /WX /MD /O2 /Ob2 /EHs-c- /GR- -UNDEBUG -std:c++17 /showIncludes /Fotools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\semantics.cpp.obj /Fdtools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\ /FS -c D:\dev\repos\llvm-project\flang\lib\Semantics\semantics.cpp
D:\dev\repos\llvm-project\flang\lib\Semantics\semantics.cpp(511): error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\flang\lib\Semantics\semantics.cpp(511): warning C4927: illegal conversion; more than one user-defined conversion has been implicitly applied
D:\dev\repos\llvm-project\flang\lib\Semantics\semantics.cpp(511): note: while calling the constructor 'Fortran::semantics::Symbol::Symbol(const Fortran::semantics::Symbol &) noexcept(false)'
D:\dev\repos\llvm-project\flang\include\flang\Semantics\symbol.h(734): note: compiler has generated 'Fortran::semantics::Symbol::Symbol' hereThis last error is different because it comes from a generated source file.
C:\PROGRA~1\MIB055~1\2022\Preview\VC\Tools\MSVC\1434~1.318\bin\Hostx64\x64\cl.exe /nologo /TP -DFLANG_LITTLE_ENDIAN=1 -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\lib\Optimizer\Dialect -ID:\dev\repos\llvm-project\flang\lib\Optimizer\Dialect -ID:\dev\repos\llvm-project\flang\include -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\include -ID:\dev\repos\llvm-project\build-nowarn\include -ID:\dev\repos\llvm-project\llvm\include -external:ID:\dev\repos\llvm-project\llvm\..\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\clang\include -external:ID:\dev\repos\llvm-project\llvm\..\clang\include -external:W0 /DWIN32 /D_WINDOWS /Zc:inline /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd4661 -wd4324 -w14062 -we4238 /Gw /WX /MD /O2 /Ob2 /EHs-c- /GR- -UNDEBUG -std:c++17 /showIncludes /Fotools\flang\lib\Optimizer\Dialect\CMakeFiles\obj.FIRDialect.dir\FIROps.cpp.obj /Fdtools\flang\lib\Optimizer\Dialect\CMakeFiles\obj.FIRDialect.dir\ /FS -c D:\dev\repos\llvm-project\flang\lib\Optimizer\Dialect\FIROps.cpp
D:\dev\repos\llvm-project\build-nowarn\tools\flang\include\flang/Optimizer/Dialect/CanonicalizationPatterns.inc(386): error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\build-nowarn\tools\flang\include\flang/Optimizer/Dialect/CanonicalizationPatterns.inc(386): warning C4927: illegal conversion; more than one user-defined conversion has been implicitly appliedNext error is because resolve-names.cpp has a function that doesn’t return a value in some path. Did this compile before?
C:\PROGRA~1\MIB055~1\2022\Preview\VC\Tools\MSVC\1434~1.318\bin\Hostx64\x64\cl.exe /nologo /TP -DFLANG_LITTLE_ENDIAN=1 -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\lib\Semantics -ID:\dev\repos\llvm-project\flang\include -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\include -ID:\dev\repos\llvm-project\build-nowarn\include -ID:\dev\repos\llvm-project\llvm\include -external:ID:\dev\repos\llvm-project\llvm\..\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\clang\include -external:ID:\dev\repos\llvm-project\llvm\..\clang\include -external:W0 /DWIN32 /D_WINDOWS /Zc:inline /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd4661 -wd4927 -wd4324 -w14062 -we4238 /Gw /WX /MD /O2 /Ob2 /EHs-c- /GR- -UNDEBUG -std:c++17 /showIncludes /Fotools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\resolve-names.cpp.obj /Fdtools\flang\lib\Semantics\CMakeFiles\obj.FortranSemantics.dir\ /FS -c D:\dev\repos\llvm-project\flang\lib\Semantics\resolve-names.cpp
D:\dev\repos\llvm-project\flang\lib\Semantics\resolve-names.cpp(2796) : error C2220: the following warning is treated as an error
D:\dev\repos\llvm-project\flang\lib\Semantics\resolve-names.cpp(2796) : warning C4715: '`Fortran::semantics::ModuleVisitor::DoAddUse'::`2'::<lambda_1>::operator()': not all control paths return a valueOh boy, them errors keep coming:
C:\PROGRA~1\MIB055~1\2022\Preview\VC\Tools\MSVC\1434~1.318\bin\Hostx64\x64\cl.exe /nologo /TP -DFLANG_LITTLE_ENDIAN=1 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\unittests\Evaluate -ID:\dev\repos\llvm-project\flang\unittests\Evaluate -ID:\dev\repos\llvm-project\flang\include -ID:\dev\repos\llvm-project\build-nowarn\tools\flang\include -ID:\dev\repos\llvm-project\build-nowarn\include -ID:\dev\repos\llvm-project\llvm\include -external:ID:\dev\repos\llvm-project\llvm\..\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\mlir\include -external:ID:\dev\repos\llvm-project\build-nowarn\tools\clang\include -external:ID:\dev\repos\llvm-project\llvm\..\clang\include -external:W0 /DWIN32 /D_WINDOWS /Zc:inline /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd4661 -wd4927 -wd4324 -w14062 -we4238 /Gw /WX /MD /O2 /Ob2 -UNDEBUG -std:c++17 /showIncludes /Fotools\flang\unittests\Evaluate\CMakeFiles\FortranEvaluateTesting.dir\fp-testing.cpp.obj /Fdtools\flang\unittests\Evaluate\CMakeFiles\FortranEvaluateTesting.dir\FortranEvaluateTesting.pdb /FS -c D:\dev\repos\llvm-project\flang\unittests\Evaluate\fp-testing.cpp
C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.34.31823\include\xtree(1664): error C2220: the following warning is treated as an error
C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.34.31823\include\xtree(1626): note: see reference to function template instantiation 'std::_Tree_node<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>,std::_Default_allocator_traits<_Alloc>::void_pointer> *std::_Tree<std::_Tmap_traits<_Kty,_Ty,_Pr,_Alloc,false>>::_Copy_nodes<std::_Tree<std::_Tmap_traits<_Kty,_Ty,_Pr,_Alloc,false>>::_Strategy::_Copy>(std::_Tree_node<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>,std::_Default_allocator_traits<_Alloc>::void_pointer> *,std::_Tree_node<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>,std::_Default_allocator_traits<_Alloc>::void_pointer> *)' being compiled
with
[
_Alloc=std::allocator<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>>,
_Kty=Fortran::parser::CharBlock,
_Ty=Fortran::common::ConstantSubscript,
_Pr=std::less<Fortran::parser::CharBlock>
]
...
C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.34.31823\include\map(109): note: while compiling class template member function 'std::map<Fortran::parser::CharBlock,Fortran::common::ConstantSubscript,std::less<Fortran::parser::CharBlock>,std::allocator<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>>>::map(const std::map<Fortran::parser::CharBlock,Fortran::common::ConstantSubscript,std::less<Fortran::parser::CharBlock>,std::allocator<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>>> &)'
D:\dev\repos\llvm-project\flang\include\flang/Evaluate/common.h(243): note: see reference to function template instantiation 'std::map<Fortran::parser::CharBlock,Fortran::common::ConstantSubscript,std::less<Fortran::parser::CharBlock>,std::allocator<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>>>::map(const std::map<Fortran::parser::CharBlock,Fortran::common::ConstantSubscript,std::less<Fortran::parser::CharBlock>,std::allocator<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>>> &)' being compiled
D:\dev\repos\llvm-project\flang\include\flang/Evaluate/common.h(291): note: see reference to class template instantiation 'std::map<Fortran::parser::CharBlock,Fortran::common::ConstantSubscript,std::less<Fortran::parser::CharBlock>,std::allocator<std::pair<const Fortran::parser::CharBlock,Fortran::common::ConstantSubscript>>>' being compiled
C:\Program Files\Microsoft Visual Studio\2022\Preview\VC\Tools\MSVC\14.34.31823\include\xtree(1664): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHscI try setting this flag just at the end of the if(MSVC) block in HandleLLVMOptions.cmake. Unfortunately, the build still fails and that’s when I notice that the earlier command lines in this post have the /EHs-c- flag. Looks like HandleLLVMOptions.cmake is explicitly removing such flags. The next logical step is to search for /EH in the codebase to see how it’s getting set for the commands that have it. That’s when I notice clang-cl – looks like a cl.exe immitation. Maybe this is how they’ve been building flang for windows without addressing all these Visual C++ issues?
There is talk of using clang-cl on non-Windows hosts to target MSVC in llvm-project/WinMsvc.cmake at 00874c48ea4d291908517afaab50d1dcbfb016c3 · llvm/llvm-project (github.com). Discovered this when investigating the packing issue in the LLVM missing headers post.
Back to the exception handling issue: searching for /EHsc leads me to AddLLVM.cmake which references the LLVM_ENABLE_EH variable. Looks like that defaults to OFF in HandleLLVMOptions.cmake and it also needs LLVM_ENABLE_RTTI to be enabled.
cmake -G Ninja ../llvm -DCMAKE_BUILD_TYPE=Release -DFLANG_ENABLE_WERROR=On -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_TARGETS_TO_BUILD=host -DCMAKE_INSTALL_PREFIX=../install -DLLVM_LIT_ARGS=-v -DLLVM_ENABLE_PROJECTS="clang;mlir;flang" -DLLVM_ENABLE_RUNTIMES="compiler-rt" -DLLVM_ENABLE_EH=ON -DLLVM_ENABLE_RTTI=ONThe fact that this still doesn’t address the warning is the red flag forcing me to notice that this is a unit test and we probably don’t want to turn on RTTI anyway. That would be a huge change! Let’s drop these flags and instead modify the flang/unittests/CMakeLists.txt to add the -EHsc flag. That turns out to be exactly the right fix! Building with this command line takes about 1hr 55min on my desktop.
mkdir build
cd build
cmake -G Ninja ../llvm -DCMAKE_BUILD_TYPE=Release -DFLANG_ENABLE_WERROR=On -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_TARGETS_TO_BUILD=host -DCMAKE_INSTALL_PREFIX=../install -DLLVM_LIT_ARGS=-v -DLLVM_ENABLE_PROJECTS="clang;mlir;flang" -DLLVM_ENABLE_RUNTIMES="compiler-rt" && ninjaAt this point, the commit I’ve been using and the Visual Studio build (17.4.0 Preview 3 with C++ compiler version 19.34.31823.3) are outdated. Let’s see what happens with the latest code and Visual Studio 17.4.0 Preview 4 (with C++ compiler version 19.34.31931). Bad timing on my part though, the installer now says Preview 5.0 is available and it comes with Microsoft (R) C/C++ Optimizing Compiler Version 19.34.31932 for x86. Not sure why these new preview builds are showing the x86 host when launching the developer command prompt from the start menu. Doesn’t happen when using the drop down in Windows Terminal.
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