Clang only picks up config files implicitly using the normalized
triple form, so use file names with "-windows-gnu" instead of
"-mingw32".
In theory, we could also want to pick up the config file implicitly
by having "<triple>-<mode>" be a symlink directly to the clang
executable. That works for regular mingw32 targets, but for the
mingw32uwp target, there's no distinction in the normalized
triple, so both would end up using the same "-windows-gnu" config
files. So as long as we want to support the mingw32uwp prefixed
tools, we need to use a wrapper.
Clang only picks up config files implicitly using the normalized
triple form, so use file names with "-windows-gnu" instead of
"-mingw32".
In theory, we could also want to pick up the config file implicitly
by having "<triple>-<mode>" be a symlink directly to the clang
executable. That works for regular mingw32 targets, but for the
mingw32uwp target, there's no distinction in the normalized
triple, so both would end up using the same "-windows-gnu" config
files. So as long as we want to support the mingw32uwp prefixed
tools, we need to use a wrapper.
Older macOS versions (macOS 12.2 at least) don't support this
option, while newer macOS versions do support it (macOS 12.6).
The solution is based on https://stackoverflow.com/a/1116890/3115956,
but simplified for this usecase.
This matches how the compiler driver normally includes default
linked libraries; the user provided -l flags are passed first,
followed by the compiler's default ones. That allows a user
specified library to override the default ones.
This makes sure that if a user provides -lwindowsappcompat, it
gets linked before -lwindowsapp, which makes a difference for
symbols that are provided in both (such as e.g. LoadLibraryW).
Clang's general default dwarf version was raised from 4 to 5 in
d3b26dea16108c427b19b5480c9edc76edf8f5b4 in llvm-project (Jan 23
2022) before the 14.0.0 branch, but dwarf 5 on Windows seems to not
work with either LLDB or GDB.
Thus force the default back to 4 here as a temporary workaround, and try
to set the default back to 4 for mingw targets in Clang for later
releases (https://reviews.llvm.org/D119326).
This makes warnings for other unused arguments visible to the user.
This requires a version of llvm-project past
50ec1306d060e46e0d53c9f5d8a052e1b0d10d3b (Jan 2022) which added these
new options.
Passing -lucrt* to the clang driver inhibits the implicit default
-lmsvcrt, so this ends up only using libucrtapp.a instead of libucrt.a.
This still requires that the default crt was ucrt, as the prebuilt
libc++.a needs to have been built for the right crt.
Since clang 9.0.0 (34ec6929a1fb33716d0035dc0f1f164d7568b4dc
in llvm-project), it's no longer necessary to set this to be able
to use __cxa_thread_atexit (for TLS destructors). This brings the
behaviour closer to GCC, and reduces the amount of non-default
options used.
For build-mingw-w64.sh to succeed when installing to such a path,
the mingw-w64 version has to be updated to the latest git master.
build-mingw-w64-libraries.sh still fails in this case, as libtool
fails to properly quote $LD in a test for whether the linker is GNU ld.
If we try to do that, clang would end up calling <triplet>-gcc with the
same arguments. In our setup, this recursively ends up calling clang again,
ending up with infinite recursion.
This allows non-msys build systems to use the triplet prefixed
compiler frontends on windows.
Keep the old shell script version as well, for easier hackability
on unix platforms.
This avoids needing the clang++ symlink. On platforms without symlinks
(i.e. windows), clang.exe and clang++.exe are two separate but identical
executables. This allows getting rid of the latter, saving size.
Provide wrappers named <triplet>-gcc and <triplet>-g++ as well,
to ease cross compilation with e.g. autotools, to allow just
specifying --host=<triplet>.
Provide wrappers for objdump and ld that provide specific output
that autotools look for.
Provide <triplet>-strip as a symlink to /bin/true, since there is
no strip tool available yet (and llvm-objcopy doesn't support
COFF yet).
Martin Storsjö