Roll buildtools to 31d4da

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 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/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 403 matching lines @@
     if ((!is_android && linux_use_bundled_binutils) ||
         !(current_cpu == "x86" || current_cpu == "x64")) {
       ldflags += [ "-Wl,--icf=all" ]
     }
   }
 
   if (linux_use_bundled_binutils) {
     cflags += [ "-B$binutils_path" ]
   }
 
+  if (is_linux) {
+    cflags += [ "-pthread" ]
+    # Do not use the -pthread ldflag here since it becomes a no-op
+    # when using -nodefaultlibs, which would cause an unused argument
+    # error.  "-lpthread" is added in //build/config:default_libs.
+  }
+
   # Clang-specific compiler flags setup.
   # ------------------------------------
   if (is_clang) {
     cflags += [ "-fcolor-diagnostics" ]
   }
 
   # Print absolute paths in diagnostics. There is no precedent for doing this
   # on Linux/Mac (GCC doesn't support it), but MSVC does this with /FC and
   # Windows developers rely on it (crbug.com/636109) so only do this on Windows.
   if (is_clang && is_win) {
@@ skipping 104 matching lines @@
 
   # Assign any flags set for the C compiler to asmflags so that they are sent
   # to the assembler. The Windows assembler takes different types of flags
   # so only do so for posix platforms.
   if (is_posix) {
     asmflags += cflags
     asmflags += cflags_c
   }
 }
 
-# This is separate from :compiler (and not even a sub-config there)
-# so that some targets can remove it from the list with:
-#   configs -= [ "//build/config/compiler:pthread" ]

[Nico, 2017/06/02 01:48:12]

Huh, I'm surprised nobody seems to do this.

-config("pthread") {
-  if (is_linux) {
-    cflags = [ "-pthread" ]
-    ldflags = [ "-pthread" ]
-  }
-}
-
 # This provides the basic options to select the target CPU and ABI.
 # It is factored out of "compiler" so that special cases can use this
 # without using everything that "compiler" brings in.  Options that
 # tweak code generation for a particular CPU do not belong here!
 # See "compiler_codegen", below.
 config("compiler_cpu_abi") {
   cflags = []
   ldflags = []
 
   if (is_posix && !(is_mac || is_ios)) {
@@ skipping 1242 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }