build/config/linux/BUILD.gn

# Copyright 2017 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import("//build/config/clang/clang.gni")
import("//build/config/sysroot.gni")
import("//build/rust/config.gni")

config("compiler") {
  cflags = []
  cflags_c = []
  cflags_cc = []
  ldflags = [
    "-static-libstdc++",

    # Generate build ID for all binaries so we can use the .build-id directory
    # scheme for debugging information. This flag is enabled by default for our
    # toolchain and many native host toolchains, but we set it explicitly to
    # support arbitrary host toolchains.
    "-Wl,--build-id",

    # Set rpath to find dynamically linked libraries placed next to executables
    # in the host build directory.
    "-Wl,-rpath=\$ORIGIN/",
  ]
  if (host_os == "mac") {
    # TODO(TC-325): When building binaries for Linux on macOS, we need to use
    # lld as a linker, hence this flag. This is not needed on Linux since our
    # Clang is configured to use lld as a default linker, but we cannot use the
    # same option on macOS since default linker is currently a per-toolchain,
    # not a per-target option and on macOS, Clang should default to ld64. We
    # should change Clang to make the default linker a per-target option.
    ldflags += [ "-fuse-ld=lld" ]
  }
  configs = [
    ":sysroot",
    ":target",
  ]

  rustflags = [
    "-Clinker=" + rebase_path("$clang_prefix/clang++", "", root_build_dir),
    "-Clink-arg=--target=$clang_target",
    "-Clink-arg=--sysroot=" + rebase_path(sysroot, root_build_dir),
    "-Cdefault-linker-libraries",
  ]

  if (!toolchain_variant.is_pic_default) {
    # Rust links are always PIE on Linux.  C/C++ static library code that is
    # linked into Rust programs must be compiled as PIE too.  Since there's no
    # good way to distinguish code going into Rust links from other code, just
    # do it for everything.  Note this doesn't cause linking as PIE, just code
    # generation that's compatible.  Non-PIE links of Linux binaries will apply
    # the relocations statically and just pay a little runtime overhead.
    cflags = [ "-fPIE" ]
  }

  # TODO(TC-74) The implicitly linked static libc++.a depends on these.
  libs = [
    "dl",
    "pthread",
  ]
  asmflags = cflags + cflags_c
}

config("sysroot") {
  cflags = [ "--sysroot=" + rebase_path(sysroot, root_build_dir) ]
  ldflags = cflags
  asmflags = cflags
}

config("target") {
  cflags = [ "--target=$clang_target" ]
  asmflags = cflags
  ldflags = cflags
}