Files
carbon-lang/toolchain/install/busybox_main.cpp
T
Chandler Carruth 444c18dfa3 Enable using our own C++ runtimes across the board (#6549)
This enables on-demand building of runtimes by default, and enables
their header files for all of the Clang invocations. This also switches
the default flags to use the LLVM-provided runtimes (compiler-rt,
libunwind, and libcxx).

This also switches even `llvm_symlinks_test` to use the Bazel prebuilt
runtimes, which requires having a way to pass a Carbon flag even when
invoking the busybox as `clang` or `clang++`. This uses the pattern that
has worked for other Clang wrappers of spelling flags:
`-X<tool-name>=--flag=value`

Last but not least, this updates the Carbon Bazel rules to use our
installed and the Bazel prebuilt runtimes. With that, we make the C++
interop hello-world be enabled by default as this should pass reliably
on both Linux and macOS now.
2026-01-07 00:16:50 +00:00

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4.5 KiB
C++

// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include <unistd.h>
#include <cstdlib>
#include <string>
#include "common/bazel_working_dir.h"
#include "common/error.h"
#include "common/init_llvm.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/LLVMDriver.h"
#include "toolchain/base/install_paths.h"
#include "toolchain/driver/driver.h"
#include "toolchain/install/busybox_info.h"
namespace Carbon {
// The actual `main` implementation. Can return an exit code or an `Error`
// (which causes EXIT_FAILRUE).
static auto Main(int argc, char** argv) -> ErrorOr<int> {
InitLLVM init_llvm(argc, argv);
// Start by resolving any symlinks.
CARBON_ASSIGN_OR_RETURN(auto busybox_info, GetBusyboxInfo(argv[0]));
std::filesystem::path exe_path = busybox_info.bin_path.string();
exe_path = SetWorkingDirForBazelRun(exe_path);
const auto install_paths = InstallPaths::MakeExeRelative(exe_path.native());
if (install_paths.error()) {
return Error(*install_paths.error());
}
// If `LLVM_SYMBOLIZER_PATH` is unset, sets it. Signals.cpp would do some more
// path resolution which this overrides in favor of using the busybox itself
// for symbolization.
setenv(
"LLVM_SYMBOLIZER_PATH",
(install_paths.llvm_install_bin().native() + "llvm-symbolizer").c_str(),
/*overwrite=*/0);
auto fs = llvm::vfs::getRealFileSystem();
llvm::SmallVector<llvm::StringRef> raw_args;
raw_args.append(argv + 1, argv + argc);
llvm::SmallVector<llvm::StringRef> args;
args.reserve(argc + 1);
if (busybox_info.mode) {
// Map busybox modes to the relevant subcommands with any flags needed to
// emulate the requested command. Typically, our busyboxed binaries redirect
// to a specific subcommand with some flags set and then pass the remaining
// busybox arguments as positional arguments to that subcommand.
//
// TODO: Add relevant flags to the `clang` subcommand and add `clang`-based
// symlinks to this like `clang++`.
auto subcommand_args =
llvm::StringSwitch<llvm::SmallVector<llvm::StringRef>>(
*busybox_info.mode)
// The `clang` program name used configures the default for its
// `--driver-mode` flag. The first of these is redundant with the
// default, but we group it here for clarity.
.Case("clang", {"clang", "--"})
.Case("clang++", {"clang", "--", "--driver-mode=g++"})
.Case("clang-cl", {"clang", "--", "--driver-mode=cl"})
.Case("clang-cpp", {"clang", "--", "--driver-mode=cpp"})
// LLD has platform-specific program names that we translate into
// platform flags.
.Case("ld.lld", {"lld", "--platform=gnu", "--"})
.Case("ld64.lld", {"lld", "--platform=darwin", "--"})
// We also support a number of LLVM tools with a trivial translation
// to subcommands. If any of these end up needing more advanced
// translation, that can be factored into the `.def` file to provide custom
// expansion here.
#define CARBON_LLVM_TOOL(Id, Name, BinName, MainFn) \
.Case(BinName, {"llvm", Name, "--"})
#include "toolchain/base/llvm_tools.def"
.Default({*busybox_info.mode, "--"});
// When we're operating as a busybox, we also support a special command line
// syntax for passing flags to the base Carbon driver as
// `-Xcarbon=--some-carbon-flag=some-value`. Extract any arguments of that
// form, remove the prefix, and prepend them to the arg list prior to the
// busybox subcommand arguments.
llvm::erase_if(raw_args, [&args](llvm::StringRef raw_arg) {
if (raw_arg.consume_front("-Xcarbon=")) {
args.push_back(raw_arg);
return true;
}
return false;
});
// And now append the subcommand args.
args.append(subcommand_args);
}
args.append(raw_args);
Driver driver(fs, &install_paths, stdin, &llvm::outs(), &llvm::errs(),
/*fuzzing=*/false, /*enable_leaking=*/true);
bool success = driver.RunCommand(args).success;
return success ? EXIT_SUCCESS : EXIT_FAILURE;
}
} // namespace Carbon
auto main(int argc, char** argv) -> int {
auto result = Carbon::Main(argc, argv);
if (result.ok()) {
return *result;
} else {
llvm::errs() << "error: " << result.error() << "\n";
return EXIT_FAILURE;
}
}