Catcrafts/Crafter.Build
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fix: key the std module's directory on everything it is compiled with

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StdPcmDir named the directory by target, march and toolchain, then
grew a case per target for the rest: the wasm flags, and with the first
fix for #43 the mingw prefix. Every other flag BuildStdPcm passes went
unkeyed, so configurations that differed only there took turns
rebuilding one std PCM in place, under the PCMs built against it: a
project with -mtune=generic against project.cpp's -mtune=native on every
run, or two sysroots for one target. And the mingw prefix was keyed only
when there was one, so a build without a prefix landed in the directory
an older release had filled with a CRAFTER_MINGW_DIR=/usr build, and
relinked its objects.

StdPcmFlags is now the one source of the flags BuildStdPcm compiles
with, and StdPcmKey names the directory by target, march and toolchain
followed by a hash of those flags and, for the mingw target, of the
prefix behind its --sysroot. VariantId hashes StdPcmKey in place of the
mingw prefix: units do not notice a std module that moved directories,
so a build has to move with it. Every std PCM directory and build
directory moves once, as after a compiler update; the old ones stay
until `clean` and the cache is cleared by hand.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
This commit is contained in:
Jorijn van der Graaf 2026-10-31 22:58:44 +01:00
commit 5d25495621
Signed by: jorijnvdgraaf
GPG key ID: 2937E59CDCC1BCFB
4 changed files with 114 additions and 65 deletions
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22
implementations/Crafter.Build-Platform.cpp
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@ -790,12 +790,10 @@ std::string Crafter::BuildStdPcm(const Configuration& config, fs::path stdPcm) {
const fs::path stdCc = (manifestPath.parent_path() / *source).lexically_normal();
if (!fs::exists(stdCc)) return std::format("{}, which {} names as the std module, is missing", stdCc.string(), manifestPath.string());
// -femulated-tls keeps PCM TLS access matching libstdc++'s emutls
// definitions; mismatch surfaces as undefined std::__once_callable.
// The std.cc → std.cppm copy uses a plain filename: held under the
// cache lock, no other builder writes this path concurrently.
fs::path stdCppm = stdPcm.parent_path() / "std.cppm";
std::string command = std::format("{} --target={} -march={} -mtune={} -femulated-tls -O3 -std=c++26 -Wno-reserved-identifier -Wno-reserved-module-identifier --precompile {} -o {}", GetBaseCommand(config), config.target, config.march, config.mtune, stdCppm.string(), stdPcm.string());
std::string command = std::format("{}{} --precompile {} -o {}", GetBaseCommand(config), StdPcmFlags(config), stdCppm.string(), stdPcm.string());
std::string stamp = HashStamp(command + '\0' + FileBytes(stdCc));
if (fs::exists(stdPcm) && ReadStamp(StampPath(stdPcm)) == stamp) return "";
std::error_code copyEc;
@ -825,27 +823,11 @@ std::string Crafter::BuildStdPcm(const Configuration& config, fs::path stdPcm) {
if (!source.error.empty()) return source.error;
stdCppm = source.stdCppm.string();
}
std::string sysrootFlag = config.sysroot.empty()
? std::string()
: std::format(" --sysroot={}", config.sysroot);
// wasm32 rejects -march, and the std module has to be compiled the way
// the units importing it are, a variant pass's flags (e.g.
// -mrelaxed-simd) included, or the BMI is not feature-compatible.
std::string archFlags = isWasm
? WasmCompileFlags(config)
: std::format(" -march={} -mtune={}", config.march, config.mtune);
// non-wasm cross builds: the driver ranks the host toolchain's own
// libc++ headers (<install>/../include/c++/v1) above --sysroot, so
// the PCM would mix host libc++ with the foreign libc — force the
// sysroot's copy.
if (!isWasm && !config.sysroot.empty()) {
archFlags += std::format(" -nostdinc++ -isystem {}/usr/include/c++/v1", config.sysroot);
}
// Keyed on the command and the module source's bytes, never on
// mtimes: an installed std.cppm can be dated at the epoch (OSTree),
// and a libc++ update under the same clang changes the bytes but
// not the path.
std::string command = std::format("{} --target={} -std=c++26{}{} -O3 -Wno-reserved-identifier -Wno-reserved-module-identifier --precompile {} -o {}", GetBaseCommand(config), config.target, sysrootFlag, archFlags, stdCppm, stdPcm.string());
std::string command = std::format("{}{} --precompile {} -o {}", GetBaseCommand(config), StdPcmFlags(config), stdCppm, stdPcm.string());
std::string stamp = HashStamp(command + '\0' + FileBytes(stdCppm));
if (fs::exists(stdPcm) && ReadStamp(StampPath(stdPcm)) == stamp) return "";
std::string result = RunBuildCommand(command);