The first fix showed clang every mingw prefix through a view of its
mingw-w64 parts. That broke a prefix that holds mingw-w64 alone, where
Windows libraries installed with --prefix land in include/ and lib/:
with CRAFTER_MINGW_DIR=/opt/mingw, <SDL2/SDL.h> and -lSDL2 were no
longer found. Such a prefix is clang's sysroot whole again. Only a
prefix that also holds a Linux system gets the view
(Toolchain::mingwPrefixIsSystem): the host's /usr inside the Flatpak,
whatever its include/ holds, and a prefix whose include/ has a C
library's features.h, which every glibc and musl header includes and
mingw-w64 has no use for, as CRAFTER_MINGW_DIR=/usr has.
MakeMingwSysroot makes the view in the cache, or in
$XDG_RUNTIME_DIR/crafter.build when the cache's filesystem takes no
symbolic links (vfat, exFAT, CIFS without unix extensions): the XDG
spec promises them there, and nothing else in the cache needs them.
Its path is absolute, because CMake runs the compiler from directories
of its own and a relative cache did not resolve from there. The prefix
is resolved once, absolute and lexically normal, so /opt/mingw/ and
/opt/mingw are one prefix and not two builds.
clang names a header by the path it found it at, so every diagnostic
from a viewed mingw-w64 header named a hashed cache directory.
RunBuildCommand now writes paths into the view as paths into the
prefix, as BuildStdPcm did for its manifest messages already.
Also from the review of PR #44: SysrootCompileFlags builds a mingw
command, which can make a view, so it redirects the cache like the
other tests; the manifest filter's comment names what it still keeps
out; the C path asks MingwSysroot() once.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
MingwSysroot stages a prefix shaped like a Linux system's /usr with a
mingw-w64 cross toolchain in it, without needing a real one: glibc's
<sys/single_threaded.h> in include/, gcc's per-target directory, and a
stand-in mingw-w64 tree whose libstdc++ has an empty std module. A
static library for x86_64-w64-mingw32, so that nothing is linked,
compiles a C++ and a C source that stop with #error when they see the
prefix's include/ or miss mingw-w64's or libstdc++'s headers. Against
the library before the fix, the C++ source stopped on
<sys/single_threaded.h>. The test also checks that the std module is
not cached in the directory older releases built it in against the
prefix itself. It needs only clang, so it runs in CI too, where no
mingw-w64 is installed.
The stand-in std module's source is written through std::format: the
build's import scanner reads string literals as code, and the literal
"export module std;" made the test itself a unit of a module std.
VariantId checks that a prefix gives a mingw configuration a variant of
its own, that two prefixes give two, and that other targets ignore it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
