carbon-lang/executable_semantics/main.cpp

// 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 <cstdio>
#include <cstring>
#include <iostream>

#include "executable_semantics/common/tracing_flag.h"
#include "executable_semantics/syntax/parse.h"
#include "executable_semantics/syntax/syntax_helpers.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/InitLLVM.h"

int main(int argc, char* argv[]) {
  llvm::InitLLVM(argc, argv);

  // Printing to stderr should flush stdout. This is most noticeable when stderr
  // is piped to stdout.
  llvm::errs().tie(&llvm::outs());

  using llvm::cl::desc;
  using llvm::cl::opt;
  opt<bool> trace_option("trace", desc("Enable tracing"));
  opt<std::string> input_file_name(llvm::cl::Positional, desc("<input file>"),
                                   llvm::cl::Required);

  llvm::cl::ParseCommandLineOptions(argc, argv);
  if (trace_option) {
    Carbon::tracing_output = true;
  }

  std::variant<Carbon::AST, Carbon::SyntaxErrorCode> ast_or_error =
      Carbon::parse(input_file_name);

  if (auto* error = std::get_if<Carbon::SyntaxErrorCode>(&ast_or_error)) {
    // Diagnostic already reported to std::cerr; this is just a return code.
    return *error;
  }

  // Typecheck and run the parsed program.
  Carbon::ExecProgram(&std::get<Carbon::AST>(ast_or_error));
}