configure_bazel.py

# Copyright 2020 The IREE Authors
#
# Licensed under the Apache License v2.0 with LLVM Exceptions.
# See https://llvm.org/LICENSE.txt for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

import platform
import os
import subprocess
import sys


def detect_unix_platform_config(bazelrc):
    # This is hoaky. Ideally, bazel had any kind of rational way of selecting
    # options from within its environment (key word: "rational"), but sadly, it
    # is unintelligible to mere mortals. Why should a build system have a way for
    # people to condition their build options on what compiler they are using
    # (without descending down the hole of deciphering what a Bazel toolchain is)?
    # All I want to do is set a couple of project specific warning options!

    if platform.system() == "Darwin":
        print(f"build --config=macos_clang", file=bazelrc)
        print(f"build:release --config=macos_clang_release", file=bazelrc)
    else:
        # If the user specified a CXX environment var, bazel will later respect that,
        # so we just see if it says "clang".
        cxx = os.environ.get("CXX")
        cc = os.environ.get("CC")
        if (cxx is not None and cc is None) or (cxx is None and cc is not None):
            print(
                "WARNING: Only one of CXX or CC is set, which can confuse bazel. "
                "Recommend: set both appropriately (or none)"
            )
        if cc is not None and cxx is not None:
            # Persist the variables.
            print(f'build --action_env CC="{cc}"', file=bazelrc)
            print(f'build --action_env CXX="{cxx}"', file=bazelrc)
        else:
            print(
                "WARNING: CC and CXX are not set, which can cause mismatches between "
                "flag configurations and compiler. Recommend setting them explicitly."
            )

        if cxx is not None and "clang" in cxx:
            print(f"Choosing generic_clang config because CXX is set to clang ({cxx})")
            print(f"build --config=generic_clang", file=bazelrc)
            print(f"build:release --config=generic_clang_release", file=bazelrc)
        else:
            print(
                f"Choosing generic_gcc config by default because no CXX set or "
                f"not recognized as clang ({cxx})"
            )
            print(f"build --config=generic_gcc", file=bazelrc)
            print(f"build:release --config=generic_gcc_release", file=bazelrc)


def write_platform(bazelrc):
    if platform.system() == "Windows":
        print(f"build --config=msvc", file=bazelrc)
        print(f"build:release --config=msvc_release", file=bazelrc)
    else:
        detect_unix_platform_config(bazelrc)


if len(sys.argv) > 1:
    local_bazelrc = sys.argv[1]
else:
    local_bazelrc = os.path.join(os.path.dirname(__file__), "configured.bazelrc")
with open(local_bazelrc, "wt") as bazelrc:
    write_platform(bazelrc)

print("Wrote", local_bazelrc)