GN win: prep_libc and fix tcmalloc linkage

base/allocator/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/allocator.gni")
+import("//build/config/win/visual_studio_version.gni")
 
 # Only executables and not libraries should depend on the allocator target;
 # only the application (the final executable) knows what allocator makes sense.
 # This "allocator" meta-target will forward to the default allocator according
 # to the build settings.
 group("allocator") {
   if (use_allocator == "tcmalloc") {
     deps = [ ":tcmalloc" ]
   }
 }
 
+config("nocmt") {
+  ldflags = [
+    "/NODEFAULTLIB:libcmt",
+    "/NODEFAULTLIB:libcmtd",
+  ]
+  libs = [ rebase_path("$target_gen_dir/allocator/libcmt.lib") ]
+}
+
 if (!is_android) {
   # tcmalloc currently won't compile on Android.
   source_set("tcmalloc") {
     tcmalloc_dir = "//third_party/tcmalloc/chromium"
 
     sources = [
       # Generated for our configuration from tcmalloc"s build
       # and checked in.
       "$tcmalloc_dir/src/config.h",
       "$tcmalloc_dir/src/config_android.h",
@@ skipping 118 matching lines @@
         # cpuprofiler
         "$tcmalloc_dir/src/base/thread_lister.c",
         "$tcmalloc_dir/src/base/thread_lister.h",
         "$tcmalloc_dir/src/profiledata.cc",
         "$tcmalloc_dir/src/profiledata.h",
         "$tcmalloc_dir/src/profile-handler.cc",
         "$tcmalloc_dir/src/profile-handler.h",
         "$tcmalloc_dir/src/profiler.cc",
       ]
       defines += [ "PERFTOOLS_DLL_DECL=" ]
+
+      direct_dependent_configs = [ ":nocmt" ]
+
+      action("prep_libc") {

[brettw, 2014/05/17 02:38:37]

Can you avoid nesting targets? I've been wanting to disallow this. Nesting is
actually super confusing since all the sources and such will be inherited in
this case from the outer scope.

[scottmg, 2014/05/17 16:29:16]

OK, I'll do that.

It seems unfortunate to move this out -- it'd be nicer if it was 1) near the one
and only place it's used; 2) could be not-visible to anything in another scope.

+        script = "prep_libc.py"
+        outputs = [ "$target_gen_dir/allocator/libcmt.lib" ]
+        args = [
+          visual_studio_path + "/vc/lib",
+          rebase_path("$target_gen_dir/allocator"),
+          cpu_arch,
+        ]
+      }
+      deps = [
+        ":prep_libc",
+      ]
     }
     if (is_linux || is_android) {
       sources -= [
         "$tcmalloc_dir/src/system-alloc.h",
         "$tcmalloc_dir/src/windows/port.cc",
         "$tcmalloc_dir/src/windows/port.h",
 
         # TODO(willchan): Support allocator shim later on.
         "allocator_shim.cc",
       ]
@@ skipping 19 matching lines @@
       ]
     }
 
     # Make sure the allocation library is optimized as much as possible when
     # we"re in release mode.
     if (!is_debug) {
       configs -= [ "//build/config/compiler:optimize" ]
       configs += [ "//build/config/compiler:optimize_max" ]
     }
 
-    deps = [
+    deps += [
       "//base/third_party/dynamic_annotations",
     ]
 
     if (is_win) {
       ldflags = [ "/ignore:4006:4221" ]
     }
   }
 }  # !is_android
 
 source_set("allocator_extension_thunks") {
   visibility = "//base/*"
   sources = [
     "allocator_extension_thunks.cc",
     "allocator_extension_thunks.h",
   ]
 }