[fusl] Build libcxx atop fusl

third_party/libcxx/BUILD.gn

+# Copyright 2016 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.
+
+config("libcxx_config") {
+  cflags = [
+    # Flags from upstream CMake build
+    "-D_DEBUG",
+    "-D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER",
+    "-D__STDC_CONSTANT_MACROS",
+    "-D__STDC_FORMAT_MACROS",
+    "-D__STDC_LIMIT_MACROS",
+    "-Dcxx_EXPORTS",
+    "-DLIBCXX_BUILDING_LIBCXXABI",
+
+    "-UNDEBUG",
+
+    "-fPIC",
+    "-fvisibility-inlines-hidden",
+
+    "-Wall",
+    "-Werror=return-type",
+
+    "-Wcast-qual",
+    "-Wcovered-switch-default",
+    "-Wdelete-non-virtual-dtor",
+    "-Wmissing-field-initializers",
+    "-Wno-error",
+    "-Wno-long-long",
+    "-Wno-long-long",
+    "-Wno-unused-parameter",
+    "-Wno-unused-parameter",
+    "-Wnon-virtual-dtor",
+    "-Wwrite-strings",
+
+    "-std=c++11",
+    "-nostdinc++",
+
+    # Use musl-based libc
+    "-D_LIBCPP_HAS_MUSL_LIBC",

[viettrungluu, 2016/01/15 23:41:50]

Is this only used in the .cpp files?

(Ditto for some of the other -D lines above.)

[Petr Hosek, 2016/01/16 02:55:02]

The problem with this approach is that everyone who includes headers from your
build of libcxx will need to define _LIBCPP_HAS_MUSL_LIBC as well which is a
pita.

In upstream libcxx, this is defined inside __config_site which is generated by
CMake from __config_site.in and later merged with __config which is then
included from all header files in libcxx.

Ideally, we would follow the same approach in our build except that doing this
in GN will require a custom action which is going to be a bit ugly.

+  ]
+}
+
+static_library("libcxx") {
+  cflags = []
+
+  configs = []
+  configs += [ ":libcxx_config" ]
+
+  include_dirs = [
+    "libcxx/include",
+    "libcxxabi/include",
+  ]
+
+  cflags += [

[viettrungluu, 2016/01/15 23:41:50]

Note: A simple "cflags = [ ... ]" here works and is sufficient (and the "cflags
= []" above becomes unnecessary).

+    "--sysroot",

[viettrungluu, 2016/01/15 23:41:50]

Is this really the right way to do this?

Should we have a toolchain definition with this? (Or at least a config with
this?)

+    "obj/fusl/sysroot",
+  ]
+
+  complete_static_lib = true
+
+  deps = [
+    "//fusl:sysroot",
+  ]
+
+  sources = [
+    "libcxx/src/algorithm.cpp",
+    "libcxx/src/any.cpp",
+    "libcxx/src/bind.cpp",
+    "libcxx/src/chrono.cpp",
+    "libcxx/src/condition_variable.cpp",
+    "libcxx/src/debug.cpp",
+    "libcxx/src/exception.cpp",
+    "libcxx/src/future.cpp",
+    "libcxx/src/hash.cpp",
+    "libcxx/src/ios.cpp",
+    "libcxx/src/iostream.cpp",
+    "libcxx/src/locale.cpp",
+    "libcxx/src/memory.cpp",
+    "libcxx/src/mutex.cpp",
+    "libcxx/src/new.cpp",
+    "libcxx/src/optional.cpp",
+    "libcxx/src/random.cpp",
+    "libcxx/src/regex.cpp",
+    "libcxx/src/shared_mutex.cpp",
+    "libcxx/src/stdexcept.cpp",
+    "libcxx/src/string.cpp",
+    "libcxx/src/strstream.cpp",
+    "libcxx/src/system_error.cpp",
+    "libcxx/src/thread.cpp",
+    "libcxx/src/typeinfo.cpp",
+    "libcxx/src/utility.cpp",
+    "libcxx/src/valarray.cpp",
+  ]
+}
+
+config("libcxxabi_config") {

[viettrungluu, 2016/01/15 23:41:50]

I wonder if we should share more of this with libcxx_config.

+  cflags = [
+    # Flags from upstream CMake build
+    "-D_DEBUG",
+    "-D__STDC_CONSTANT_MACROS",
+    "-D__STDC_FORMAT_MACROS",
+    "-D__STDC_LIMIT_MACROS",
+
+    "-fPIC",
+    "-fstrict-aliasing",
+    "-fvisibility-inlines-hidden",
+
+    "-Wall",
+    "-Wcast-qual",
+    "-Wchar-subscripts",
+    "-Wconversion",
+    "-Wcovered-switch-default",
+    "-Wdelete-non-virtual-dtor",
+    "-Werror=return-type",
+    "-Wmismatched-tags",
+    "-Wmissing-braces",
+    "-Wmissing-field-initializers",
+    "-Wnewline-eof",
+    "-Wno-error",
+    "-Wno-long-long",
+    "-Wno-unused-function",
+    "-Wno-unused-parameter",
+    "-Wnon-virtual-dtor",
+    "-Wshadow",
+    "-Wshorten-64-to-32",
+    "-Wsign-compare",
+    "-Wsign-conversion",
+    "-Wstrict-aliasing=2",
+    "-Wstrict-overflow=4",
+    "-Wundef",
+    "-Wunused-parameter",
+    "-Wunused-variable",
+    "-Wwrite-strings",
+    "-Wwrite-strings",
+
+    "-std=c++11",
+    "-pedantic",
+    "-nostdinc++",
+
+    # Use musl-based libc
+    "-D_LIBCPP_HAS_MUSL_LIBC",
+  ]
+}
+
+static_library("libcxxabi") {
+  cflags = []
+
+  configs = []
+  configs += [ ":libcxxabi_config" ]
+
+  include_dirs = [
+    "libcxx/include",
+    "libcxxabi/include",
+  ]
+
+  cflags += [
+    "--sysroot",
+    "obj/fusl/sysroot",
+  ]
+
+  complete_static_lib = true
+
+  deps = [
+    "//fusl:sysroot",
+  ]
+
+  sources = [
+    "libcxxabi/src/abort_message.cpp",
+    "libcxxabi/src/cxa_aux_runtime.cpp",
+    "libcxxabi/src/cxa_default_handlers.cpp",
+    "libcxxabi/src/cxa_demangle.cpp",
+    "libcxxabi/src/cxa_exception.cpp",
+    "libcxxabi/src/cxa_exception_storage.cpp",
+    "libcxxabi/src/cxa_guard.cpp",
+    "libcxxabi/src/cxa_handlers.cpp",
+    "libcxxabi/src/cxa_new_delete.cpp",
+    "libcxxabi/src/cxa_personality.cpp",
+    "libcxxabi/src/cxa_thread_atexit.cpp",
+    "libcxxabi/src/cxa_unexpected.cpp",
+    "libcxxabi/src/cxa_vector.cpp",
+    "libcxxabi/src/cxa_virtual.cpp",
+    "libcxxabi/src/exception.cpp",
+    "libcxxabi/src/private_typeinfo.cpp",
+    "libcxxabi/src/stdexcept.cpp",
+    "libcxxabi/src/typeinfo.cpp",
+  ]
+}