// 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 "toolchain/driver/clang_subcommand.h"

#include <string>

#include "llvm/TargetParser/Host.h"
#include "toolchain/driver/clang_runner.h"

namespace Carbon {

auto ClangOptions::Build(CommandLine::CommandBuilder& b) -> void {
  b.AddStringPositionalArg(
      {
          .name = "ARG",
          .help = R"""(
Arguments passed to Clang.
)""",
      },
      [&](auto& arg_b) { arg_b.Append(&args); });
}

static constexpr CommandLine::CommandInfo SubcommandInfo = {
    .name = "clang",
    .help = R"""(
Runs Clang on arguments.

This is equivalent to running the `clang` command line directly, and provides
the full command line interface.

Use `carbon clang -- ARGS` to pass flags to `clang`. Although there are
currently no flags for `carbon clang`, the `--` reserves the ability to add
flags in the future.

This is provided to help guarantee consistent compilation of C++ files, both
when Clang is invoked directly and when a Carbon file importing a C++ file
results in an indirect Clang invocation.
)""",
};

ClangSubcommand::ClangSubcommand() : DriverSubcommand(SubcommandInfo) {}

// TODO: This lacks a lot of features from the main driver code. We may need to
// add more.
// https://github.com/llvm/llvm-project/blob/main/clang/tools/driver/driver.cpp
auto ClangSubcommand::Run(DriverEnv& driver_env) -> DriverResult {
  ClangRunner runner(driver_env.installation, driver_env.fs,
                     driver_env.vlog_stream);

  // Don't run Clang when fuzzing, it is known to not be reliable under fuzzing
  // due to many unfixed issues.
  if (TestAndDiagnoseIfFuzzingExternalLibraries(driver_env, "clang")) {
    return {.success = false};
  }

  ErrorOr<bool> run_result = false;
  if (driver_env.prebuilt_runtimes) {
    run_result = runner.RunWithPrebuiltRuntimes(options_.args,
                                                *driver_env.prebuilt_runtimes,
                                                driver_env.enable_leaking);
  } else if (driver_env.build_runtimes_on_demand) {
    run_result = runner.Run(options_.args, driver_env.runtimes_cache,
                            *driver_env.thread_pool, driver_env.enable_leaking);
  } else {
    run_result =
        runner.RunWithNoRuntimes(options_.args, driver_env.enable_leaking);
  }
  if (!run_result.ok()) {
    // This is not a Clang failure, but a failure to even run Clang, so we need
    // to diagnose it here.
    CARBON_DIAGNOSTIC(FailureRunningClang, Error,
                      "failure running `clang` subcommand: {0}", std::string);
    driver_env.emitter.Emit(FailureRunningClang, run_result.error().message());
    return {.success = false};
  }

  // Successfully ran Clang, but return whether Clang itself succeeded.
  return {.success = *run_result};
}

}  // namespace Carbon
