Files
OrcaSlicer/cmake/modules/ClangClShowIncludes.cmake
T
Kris Austin 0db1dc6480 build: keep header dependencies through a compiler cache hit on clang-cl (#15875)
For clang-cl, CMake sets the depfile flags to the gcc-style -MD, -MT and -MF,
passed through as -clang: arguments. ccache does not parse those, so a cache
hit writes only the object. Ninja has no depfile to read, so it records zero
header dependencies for that object and does not rebuild it after a header
edit. The stale object is still linked into the library and the DLL. sccache
0.15.0 reproduces the depfile on a hit and is unaffected.

Use /showIncludes instead. CMake already does that for MSVC, and ccache
reproduces it on a hit. A make-rules override sets the flags, because CMake
includes the override after Platform/Windows-Clang.cmake. It is forwarded to
each dependency because every one configures as its own CMake project, and it
is only set when the file exists, because scripts/flatpak/make_deps_tar.sh
packs deps/ alone.

In a build with a warm cache, 678 of 790 objects had no recorded headers.
Object code does not change. One GUI translation unit compiled both ways is
byte-identical apart from the COFF timestamp.
2026-09-24 14:06:24 -03:00

11 lines
521 B
CMake

# ccache does not parse the -clang: arguments CMake uses for clang-cl's gcc-style
# depfile, so a cache hit writes the object and no depfile, and Ninja then records
# no headers for that object. ccache reproduces /showIncludes output on a hit.
foreach (_lang C CXX)
if (CMAKE_${_lang}_COMPILER_ID STREQUAL "Clang" AND
CMAKE_${_lang}_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
set(CMAKE_DEPFILE_FLAGS_${_lang} "/showIncludes")
set(CMAKE_${_lang}_DEPFILE_FORMAT msvc)
endif ()
endforeach ()