[flang] Use the equivalent compilation flags with MSVC.

[isuruf]

Using https://github.com/flang-compiler/f18/pull/1095/files should add -fno-rtti and -fno-exceptions automatically on unix and add the equivalent flags on windows as well.

[ChinouneMehdi]

In D78185#1983321, @isuruf wrote:

Using https://github.com/flang-compiler/f18/pull/1095/files should add -fno-rtti and -fno-exceptions automatically on unix and add the equivalent flags on windows as well.

Yes, but what about tests and other libraries ?

[DavidTruby]

At a first glance this looks good to me, but I am not that familiar with MSVC. I can approve but someone with more Windows experience should approve as well before you commit.

[isuruf]

Yes, but what about tests and other libraries ?

I think tests are fine if they don't use it. Using add_flang_library should make flang consistent with the rest of LLVM.

[ChinouneMehdi]

Superseded by D78306

flang/CMakeLists.txt

configure_file(
   ${CMAKE_CURRENT_SOURCE_DIR}/include/flang/Version.inc.in
   ${CMAKE_CURRENT_BINARY_DIR}/include/flang/Version.inc)
 # Configure Flang's version info header file.
 configure_file(
   ${FLANG_SOURCE_DIR}/include/flang/Config/config.h.cmake
   ${FLANG_BINARY_DIR}/include/flang/Config/config.h)
 
 # Add global F18 flags.
+if(MSVC)
+  set(CMAKE_CXX_FLAGS "/GR- /EHs-c- /Wall ${CMAKE_CXX_FLAGS}")
+else()
   set(CMAKE_CXX_FLAGS "-fno-rtti -fno-exceptions -pedantic -Wall -Wextra -Werror -Wcast-qual -Wimplicit-fallthrough -Wdelete-non-virtual-dtor ${CMAKE_CXX_FLAGS}")
+endif()
 
 # Builtin check_cxx_compiler_flag doesn't seem to work correctly
 macro(check_compiler_flag flag resultVar)
   unset(${resultVar} CACHE)
   check_cxx_compiler_flag("${flag}" ${resultVar})
 endmacro()
 
 check_compiler_flag("-Werror -Wno-deprecated-copy" CXX_SUPPORTS_NO_DEPRECATED_COPY_FLAG)

flang/lib/Optimizer/CMakeLists.txt

 # Sources generated by tablegen have unused parameters.
+if(MSVC)
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd4100")
+else()
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-unused-parameter")
+endif()
 
 add_subdirectory(Dialect)
 add_subdirectory(Support)