Replace Bazel's custom unix_cc_configure with a wrapper script.

bazel/cc_configure.bzl

@@ -1,56 +1,48 @@
-# This file was imported from https://github.com/bazelbuild/bazel at 3d00b2a. We apply a number of
-# local modifications to deal with known issues in Bazel 0.10.0.
-#
-# * https://github.com/bazelbuild/bazel/issues/2840
-# * (and potentially) https://github.com/bazelbuild/bazel/issues/2805
-#
-# See cc_configure.bzl.diff for the changes made in this fork.
+load("@bazel_tools//tools/cpp:cc_configure.bzl", _upstream_cc_autoconf_impl = "cc_autoconf_impl")
+load("@bazel_tools//tools/cpp:lib_cc_configure.bzl", "get_cpu_value")
+load("@bazel_tools//tools/cpp:unix_cc_configure.bzl", "find_cc")
 
-# Copyright 2016 The Bazel Authors. All rights reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#    http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-"""Rules for configuring the C++ toolchain (experimental)."""
+def _quiet_fake_which(program):
+  return struct(_envoy_fake_which = program)
 
+def _noisy_fake_which(program):
+  return None
 
-load("@bazel_tools//tools/cpp:windows_cc_configure.bzl", "configure_windows_toolchain")
-load("@bazel_tools//tools/cpp:osx_cc_configure.bzl", "configure_osx_toolchain")
-load("//bazel:unix_cc_configure.bzl", "configure_unix_toolchain")
-load("@bazel_tools//tools/cpp:lib_cc_configure.bzl", "get_cpu_value")
+def _build_envoy_cc_wrapper(repository_ctx):
+  real_cc = find_cc(repository_ctx, {})
+  environ_cxx = repository_ctx.os.environ.get("CXX", "g++")
+  fake_os = struct(
+    environ = {"CC": environ_cxx},
+  )
+  real_cxx = find_cc(struct(
+      which = _quiet_fake_which,
+      os = fake_os,
+  ), {})
+  if hasattr(real_cxx, "_envoy_fake_which"):
+    real_cxx = repository_ctx.which(real_cxx._envoy_fake_which)
+    if real_cxx == None:
+      find_cc(struct(
+        which = _noisy_fake_which,
+        os = fake_os,
+      ), {})
+  repository_ctx.template("envoy_cc_wrapper", repository_ctx.attr._envoy_cc_wrapper, {
+      "{ENVOY_REAL_CC}": repr(str(real_cc)),
+      "{ENVOY_REAL_CXX}": repr(str(real_cxx)),
+  })
+  return repository_ctx.path("envoy_cc_wrapper")
 
-def cc_autoconf_impl(repository_ctx, overriden_tools = dict()):
-  repository_ctx.symlink(
-      Label("@bazel_tools//tools/cpp:dummy_toolchain.bzl"), "dummy_toolchain.bzl")
-  env = repository_ctx.os.environ
+def cc_autoconf_impl(repository_ctx):
   cpu_value = get_cpu_value(repository_ctx)
-  if cpu_value == "freebsd":
-    # This is defaulting to the static crosstool, we should eventually
-    # autoconfigure this platform too.  Theorically, FreeBSD should be
-    # straightforward to add but we cannot run it in a docker container so
-    # skipping until we have proper tests for FreeBSD.
-    repository_ctx.symlink(Label("@bazel_tools//tools/cpp:CROSSTOOL"), "CROSSTOOL")
-    repository_ctx.symlink(Label("@bazel_tools//tools/cpp:BUILD.static"), "BUILD")
-  elif cpu_value == "x64_windows":
-    # TODO(ibiryukov): overriden_tools are only supported in configure_unix_toolchain.
-    # We might want to add that to Windows too(at least for msys toolchain).
-    configure_windows_toolchain(repository_ctx)
-  elif (cpu_value == "darwin" and
-      ("BAZEL_USE_CPP_ONLY_TOOLCHAIN" not in env or env["BAZEL_USE_CPP_ONLY_TOOLCHAIN"] != "1")):
-    configure_osx_toolchain(repository_ctx, overriden_tools)
-  else:
-    configure_unix_toolchain(repository_ctx, cpu_value, overriden_tools)
+  overriden_tools = {}
+  if cpu_value not in ["freebsd", "x64_windows", "darwin"]:
+    overriden_tools["gcc"] = _build_envoy_cc_wrapper(repository_ctx)
+  return _upstream_cc_autoconf_impl(repository_ctx, overriden_tools=overriden_tools)
 
 cc_autoconf = repository_rule(
     implementation = cc_autoconf_impl,
+    attrs = {
+        "_envoy_cc_wrapper": attr.label(default="@envoy//bazel:cc_wrapper.py"),
+    },
     environ = [
         "ABI_LIBC_VERSION",
         "ABI_VERSION",
@@ -65,6 +57,7 @@ cc_autoconf = repository_rule(
         "BAZEL_VC",
         "BAZEL_VS",
         "CC",
+        "CXX",
         "CC_CONFIGURE_DEBUG",
         "CC_TOOLCHAIN_NAME",
         "CPLUS_INCLUDE_PATH",
@@ -82,8 +75,6 @@ cc_autoconf = repository_rule(
         "VS120COMNTOOLS",
         "VS140COMNTOOLS"])
 
-
 def cc_configure():
-  """A C++ configuration rules that generate the crosstool file."""
   cc_autoconf(name="local_config_cc")
   native.bind(name="cc_toolchain", actual="@local_config_cc//:toolchain")

bazel/cc_wrapper.py

@@ -0,0 +1,54 @@
+#!/usr/bin/python
+import os
+import sys
+import tempfile
+
+envoy_real_cc = {ENVOY_REAL_CC}
+envoy_real_cxx = {ENVOY_REAL_CXX}
+
+def sanitize_flagfile(in_path, out_fd):
+    with open(in_path, "rb") as in_fp:
+        for line in in_fp:
+            if line != "-lstdc++\n":
+                os.write(out_fd, line)
+
+def main():
+    compiler = envoy_real_cc
+
+    # Debian's packaging of Clang requires `-no-canonical-prefixes` to print
+    # consistent include paths, but Bazel 0.10 only sets that option at compile
+    # time. We inject it here for the configuration of `@local_config_cc//`.
+    #
+    # https://github.com/bazelbuild/bazel/issues/3977
+    # https://github.com/bazelbuild/bazel/issues/4572
+    # https://bazel-review.googlesource.com/c/bazel/+/39951
+    if sys.argv[1:] == ["-E", "-xc++", "-", "-v"] and "clang" in compiler:
+        os.execv(envoy_real_cxx, [envoy_real_cxx, "-E", "-", "-v", "-no-canonical-prefixes"])
+
+    # `g++` and `gcc -lstdc++` have similar behavior and Bazel treats them as
+    # interchangeable, but `gcc` will ignore the `-static-libstdc++` flag.
+    # This check lets Envoy statically link against libstdc++ to be more
+    # portable between intalled glibc versions.
+    if "-static-libstdc++" in sys.argv[1:]:
+        compiler = envoy_real_cxx
+        argv = []
+        for arg in sys.argv[1:]:
+            if arg == "-lstdc++":
+                pass
+            elif arg.startswith("-Wl,@"):
+                # tempfile.mkstemp will write to the out-of-sandbox tempdir
+                # unless the user has explicitly set environment variables
+                # before starting Bazel. But here in $PWD is the Bazel sandbox,
+                # which will be deleted automatically after the compiler exits.
+                (flagfile_fd, flagfile_path) = tempfile.mkstemp(dir='./', suffix=".linker-params")
+                sanitize_flagfile(arg[len("-Wl,@"):], flagfile_fd)
+                os.close(flagfile_fd)
+                argv.append("-Wl,@" + flagfile_path)
+            else:
+                argv.append(arg)
+    else:
+        argv = sys.argv[1:]
+    os.execv(compiler, [compiler] + argv)
+
+if __name__ == "__main__":
+    main()