Move c++flags config inclusion from compiler to runtime_library

R=dpranke@chromium.org
CC=thakis@chromium.org

Change-Id: I6ed223a1fe08fa95837156ae9f4800acf7396524
Reviewed-on: https://chromium-review.googlesource.com/592512Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491145}

build/config/c++/BUILD.gn

-# Copyright 2017 The Chromium 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/c++/c++.gni")
-import("//build/config/sysroot.gni")
-
-config("c++flags") {
-  if (use_custom_libcxx) {
-    if (!is_clang) {
-      # Gcc has a built-in abs() definition with default visibility.
-      # If it was not disabled, it would conflict with libc++'s abs()
-      # with hidden visibility.
-      cflags = [ "-fno-builtin-abs" ]
-    }
-    cflags_cc = [
-      "-nostdinc++",
-      "-isystem" + rebase_path("$libcxx_prefix/include", root_build_dir),
-      "-isystem" + rebase_path("$libcxxabi_prefix/include", root_build_dir),
-    ]
-
-    # This condition should match the one in buildtools/third_party/libc++abi.
-    if ((is_linux && current_cpu == "arm") || is_fuchsia) {
-      cflags_c = [ "-isystem" +
-                   rebase_path("$libunwind_prefix/include", root_build_dir) ]
-      cflags_cc += [ "-isystem" +
-                     rebase_path("$libunwind_prefix/include", root_build_dir) ]
-    }
-
-    # Make sure we don't link against libc++ or libstdc++.
-    ldflags = [ "-nodefaultlibs" ]
-
-    # Unfortunately, there's no way to disable linking against just
-    # libc++ (besides using clang instead of clang++); -nodefaultlibs
-    # removes all of the default libraries, so add back the ones that we
-    # need.
-    libs = [
-      "c",
-      "m",
-    ]
-
-    if (!is_mac && !is_fuchsia) {
-      libs += [
-        "gcc_s",
-        "rt",
-      ]
-    } else if (is_fuchsia) {
-      # TODO(thakis): Once Fuchsia's libclang_rt.builtin no longer has upstream
-      # patches, we might want to make tools/clang/scripts/update.py build it
-      # and bundle it with the clang package instead of using the library from
-      # the SDK, https://crbug.com/724204
-      # If clang grows a flag like -nodefaultlibs++, then this here should use
-      # -resource-dir instead.
-      # Note: Intentionally 6.0.0 instead of $clang_version because the clang
-      # version of the toolchain_libs directory in the Fuchsia SDK can be
-      # different from the version of Chromium's clang.
-      lib_dirs = [ "$fuchsia_sdk/toolchain_libs/clang/6.0.0/lib/fuchsia" ]
-
-      # TODO(fuchsia): We probably want to support more archs one day.
-      libs += [ "clang_rt.builtins-x86_64" ]
-    }
-
-    if (is_mac && using_sanitizer) {
-      lib_dirs = [ "//third_party/llvm-build/Release+Asserts/lib/clang/$clang_version/lib/darwin" ]
-
-      if (is_asan) {
-        libs += [ "clang_rt.asan_osx_dynamic" ]
-      }
-    }
-  }
-}

build/config/compiler/BUILD.gn

@@ -182,8 +182,6 @@ config("compiler") {
   }
 
   configs += [
-    "//build/config/c++:c++flags",
-
     # See the definitions below.
     ":compiler_cpu_abi",
     ":compiler_codegen",

build/config/posix/BUILD.gn

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/c++/c++.gni")
 import("//build/config/clang/clang.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/sysroot.gni")
@@ -18,11 +19,84 @@ group("posix") {
 # that is Posix-only. Please see that target for advice on what should go in
 # :runtime_library vs. :compiler.
 config("runtime_library") {
+  asmflags = []
+  cflags = []
+  cflags_c = []
+  cflags_cc = []
+  cflags_objc = []
+  cflags_objcc = []
+  ldflags = []
+  lib_dirs = []
+  libs = []
+
+  if (use_custom_libcxx) {
+    if (!is_clang) {
+      # Gcc has a built-in abs() definition with default visibility.
+      # If it was not disabled, it would conflict with libc++'s abs()
+      # with hidden visibility.
+      cflags += [ "-fno-builtin-abs" ]
+    }
+    cflags_cc += [
+      "-nostdinc++",
+      "-isystem" + rebase_path("$libcxx_prefix/include", root_build_dir),
+      "-isystem" + rebase_path("$libcxxabi_prefix/include", root_build_dir),
+    ]
+
+    # This condition should match the one in buildtools/third_party/libc++abi.
+    if ((is_linux && current_cpu == "arm") || is_fuchsia) {
+      cflags_c += [ "-isystem" +
+                    rebase_path("$libunwind_prefix/include", root_build_dir) ]
+      cflags_cc += [ "-isystem" +
+                     rebase_path("$libunwind_prefix/include", root_build_dir) ]
+    }
+
+    # Make sure we don't link against libc++ or libstdc++.
+    ldflags += [ "-nodefaultlibs" ]
+
+    # Unfortunately, there's no way to disable linking against just
+    # libc++ (besides using clang instead of clang++); -nodefaultlibs
+    # removes all of the default libraries, so add back the ones that we
+    # need.
+    libs += [
+      "c",
+      "m",
+    ]
+
+    if (!is_mac && !is_fuchsia) {
+      libs += [
+        "gcc_s",
+        "rt",
+      ]
+    } else if (is_fuchsia) {
+      # TODO(thakis): Once Fuchsia's libclang_rt.builtin no longer has upstream
+      # patches, we might want to make tools/clang/scripts/update.py build it
+      # and bundle it with the clang package instead of using the library from
+      # the SDK, https://crbug.com/724204
+      # If clang grows a flag like -nodefaultlibs++, then this here should use
+      # -resource-dir instead.
+      # Note: Intentionally 6.0.0 instead of $clang_version because the clang
+      # version of the toolchain_libs directory in the Fuchsia SDK can be
+      # different from the version of Chromium's clang.
+      lib_dirs += [ "$fuchsia_sdk/toolchain_libs/clang/6.0.0/lib/fuchsia" ]
+
+      # TODO(fuchsia): We probably want to support more archs one day.
+      libs += [ "clang_rt.builtins-x86_64" ]
+    }
+
+    if (is_mac && using_sanitizer) {
+      lib_dirs += [ "//third_party/llvm-build/Release+Asserts/lib/clang/$clang_version/lib/darwin" ]
+
+      if (is_asan) {
+        libs += [ "clang_rt.asan_osx_dynamic" ]
+      }
+    }
+  }
+
   if (!is_mac && !is_ios && sysroot != "") {
     # Pass the sysroot to all C compiler variants, the assembler, and linker.
     sysroot_flags = [ "--sysroot=" + rebase_path(sysroot, root_build_dir) ]
-    asmflags = sysroot_flags
-    ldflags = sysroot_flags
+    asmflags += sysroot_flags
+    ldflags += sysroot_flags
 
     # When use_custom_libcxx=true, some -isystem flags get passed to
     # cflags_cc to set up libc++ include paths.  We want to make sure
@@ -32,10 +106,10 @@ config("runtime_library") {
     # cflags* will be appended on the compiler command line after
     # 'cflags'."  Because of this, we must set the sysroot flags for
     # all cflags variants instead of using 'cflags' directly.
-    cflags_c = sysroot_flags
-    cflags_cc = sysroot_flags
-    cflags_objc = sysroot_flags
-    cflags_objcc = sysroot_flags
+    cflags_c += sysroot_flags
+    cflags_cc += sysroot_flags
+    cflags_objc += sysroot_flags
+    cflags_objcc += sysroot_flags
 
     # Need to get some linker flags out of the sysroot.
     ld_paths = exec_script("sysroot_ld_path.py",