Put GN object files in subdir based on the label.

build/toolchain/win/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.
 
 declare_args() {
   # Path to the directory containing the VC binaries for the right
   # combination of host and target architectures. Currently only the
   # 64-bit host toolchain is supported, with either 32-bit or 64-bit targets.
   # If vc_bin_dir is not specified on the command line (and it normally
   # isn't), we will dynamically determine the right value to use at runtime.
@@ skipping 66 matching lines @@
 
   env = invoker.environment
 
   cl = invoker.cl
 
   toolchain(target_name) {
     # Make these apply to all tools below.
     lib_switch = ""
     lib_dir_switch = "/LIBPATH:"
 
+    # Object files go in this directory.
+    object_subdir = "{{target_out_dir}}/{{label_name}}"
+
     tool("cc") {
       rspfile = "{{output}}.rsp"
       precompiled_header_type = "msvc"
       pdbname = "{{target_out_dir}}/{{target_output_name}}_c.pdb"
       command = "ninja -t msvc -e $env -- $cl /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}} /Fd$pdbname"
       depsformat = "msvc"
       description = "CC {{output}}"
       outputs = [
-        "{{target_out_dir}}/{{target_output_name}}/{{source_name_part}}.obj",
+        "$object_subdir/{{source_name_part}}.obj",
       ]
       rspfile_content = "{{defines}} {{include_dirs}} {{cflags}} {{cflags_c}}"
     }
 
     tool("cxx") {
       rspfile = "{{output}}.rsp"
       precompiled_header_type = "msvc"
 
       # The PDB name needs to be different between C and C++ compiled files.
       pdbname = "{{target_out_dir}}/{{target_output_name}}_cc.pdb"
       command = "ninja -t msvc -e $env -- $cl /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}} /Fd$pdbname"
       depsformat = "msvc"
       description = "CXX {{output}}"
       outputs = [
-        "{{target_out_dir}}/{{target_output_name}}/{{source_name_part}}.obj",
+        "$object_subdir/{{source_name_part}}.obj",
       ]
       rspfile_content = "{{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}}"
     }
 
     tool("rc") {
       command = "$python_path gyp-win-tool rc-wrapper $env rc.exe {{defines}} {{include_dirs}} /fo{{output}} {{source}}"
       outputs = [
-        "{{target_out_dir}}/{{target_output_name}}/{{source_name_part}}.res",
+        "$object_subdir/{{source_name_part}}.res",
       ]
       description = "RC {{output}}"
     }
 
     tool("asm") {
       if (current_cpu == "x64") {
         ml = "ml64.exe"
       } else {
         ml = "ml.exe"
       }
       command = "$python_path gyp-win-tool asm-wrapper $env $ml {{defines}} {{include_dirs}} {{asmflags}} /c /Fo{{output}} {{source}}"
       description = "ASM {{output}}"
       outputs = [
-        "{{target_out_dir}}/{{target_output_name}}/{{source_name_part}}.obj",
+        "$object_subdir/{{source_name_part}}.obj",
       ]
     }
 
     tool("alink") {
       rspfile = "{{output}}.rsp"
       command = "$python_path gyp-win-tool link-wrapper $env False lib.exe /nologo /ignore:4221 /OUT:{{output}} @$rspfile"
       description = "LIB {{output}}"
       outputs = [
         # Ignore {{output_extension}} and always use .lib, there's no reason to
         # allow targets to override this extension on Windows.
@@ skipping 152 matching lines @@
 }
 
 msvc_toolchain("winrt_x64") {
   environment = "environment.winrt_x64"
   cl = "${goma_prefix}\"${vc_bin_dir}/cl.exe\""
   is_clang = false
 
   current_cpu = "x64"
   current_os = current_os
 }