Remove the GN cookbook document.
This document was for listing equivalents between GYP and GN which are no longer relevant.
Many of the items our out-of-date already, and it is not being updated further. I have already removed the references to this document from the Google Sites pages.
Review-Url: https://codereview.chromium.org/2505133004
Cr-Original-Commit-Position: refs/heads/master@{#432897}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 6afdb84319431eb94809a5f2ef9f33960dd2dea6
diff --git a/tools/gn/README.md b/tools/gn/README.md
index ad731a6..4f90505 100644
--- a/tools/gn/README.md
+++ b/tools/gn/README.md
@@ -38,7 +38,6 @@
* [Quick start](https://chromium.googlesource.com/chromium/src/+/master/tools/gn/docs/quick_start.md)
* [FAQ](https://chromium.googlesource.com/chromium/src/+/master/tools/gn/docs/faq.md)
- * [GYP conversion cookbook](https://chromium.googlesource.com/chromium/src/+/master/tools/gn/docs/cookbook.md)
* [Language and operation details](https://chromium.googlesource.com/chromium/src/+/master/tools/gn/docs/language.md)
* [Reference](https://chromium.googlesource.com/chromium/src/+/master/tools/gn/docs/reference.md) The built-in `gn help` documentation.
* [Style guide](https://chromium.googlesource.com/chromium/src/+/master/tools/gn/docs/style_guide.md)
diff --git a/tools/gn/docs/cookbook.md b/tools/gn/docs/cookbook.md
deleted file mode 100644
index 390fbf1..0000000
--- a/tools/gn/docs/cookbook.md
+++ /dev/null
@@ -1,681 +0,0 @@
-# GYP->GN Conversion Cookbook
-
-[TOC]
-
-## Targets
-
-| *GYP* | *GN* |
-|:-------------------------------------------------|:---------------------------------------------------|
-| `'type': 'static_library', 'name': 'foo',` | `static_library("foo") {` or `source_set("foo") {` |
-| `'type': 'shared_library', 'name': 'foo',` | `shared_library("foo") {` |
-| `'type': 'loadable_module', 'name': 'foo',` | `loadable_module("foo") {` |
-| `'type': '<(component)', 'name': 'foo',` | `component("foo") {` |
-| `'type': 'executable', 'name': 'foo',` | `executable("foo") {` |
-| `'type': '<(gtest_target_type)', 'name': 'foo',` | `test("foo") {` |
-| `'type': 'none', 'name': 'foo',` | `group("foo") {` |
-
-### Note on static libraries
-
-A source\_set is basically a transparent static\_library. The source files
-are compiled with the given options but not linked into anything.
-Targets that depend on a source set get the source set's object files
-linked into it. This saves the overhead of creating a static library on
-disk, avoids weird linker issues when a static library has no source
-files, and you can link source sets into shared libraries and have
-symbols exported from the shared library.
-
-The last issue is a cause of a lot of headaches in the GYP build. If you
-annotate a symbol as exported (i.e. `BASE_EXPORT`) then you can't have
-it in a file that goes into a static library because the function might
-be [stripped out](http://blogs.msdn.com/b/oldnewthing/archive/2014/03/21/10509670.aspx)
-if it's not called from within the static library. This
-prevents composing components of static libraries and exporting their
-symbols. A source set avoids this issue and `EXPORT` has the desired
-meaning of "export from the component this gets linked into" with no
-surprising dead code stripping behavior.
-
-A disadvantage of source sets is that if an object file is completely
-unused, it will still be linked into the result, which is not the case
-for static libraries. A few places in the build depend on this behavior
-(deliberately or accidentally). In general, small libraries that we
-expect to be entirely used, test helpers, etc. can be source sets. There
-is slightly less risk of subtle issues if you keep static libraries
-static libraries, however.
-
-### Actions
-
-GYP
-
-```
-{
- 'action_name': 'foo',
- 'inputs': [ 'bar.py' ],
- 'outputs': [ '<(SHARED_INTERMEDIATE_DIR)/bar.out' ],
- 'action': ['python', 'bar.py', '--la_dee_da' ],
-},
-```
-
-Unlike GYP, where an action is a part of a target, GN actions are
-separate targets that you then depend on via deps from other targets:
-
-```
-action("foo") {
- script = "bar.py"
- outputs = [ "$target_gen_dir/bar.out" ]
- args = [ "--la_dee_da" ]
-}
-
-executable("foo.exe") {
- ...
- deps = [ ":foo" ] # Depend on the action to make sure it runs.
-}
-```
-
-Rules in GYP become `action_foreach` in GN which work like actions but
-iterate over a set of sources.
-
-### Copies
-
-GYP
-
-```
-'copies': [
- {
- 'destination': '<(PRODUCT_DIR)/',
- 'files': [
- '../build/win/dbghelp_xp/dbghelp.dll',
- ],
- },
-],
-```
-
-Unlike GYP, where copies are part of a target, GN copies are
-separate targets that you then depend on via deps from other targets:
-
-```
-copy("bar") {
- sources = [ "../path/to/secret.dll" ]
- outputs = [ "$root_out_dir/{{source_file_part}}" ]
-}
-
-component("base") {
- ...
- deps = [ "bar" } # Depend on the copy to make sure it runs.
-}
-```
-
-## Platform checking
-
-| *GYP* | *GN* |
-|:-------------------------------------|:---------------------|
-| `'conditions': [['OS=="win"', {` | `if (is_win) {` |
-| `'conditions': [['OS=="linux"', {` | `if (is_linux) {` |
-| `'conditions': [['OS=="android"', {` | `if (is_android) {` |
-| `'conditions': [['OS=="mac"', {` | `if (is_mac) {` |
-| `'conditions': [['OS=="ios"', {` | `if (is_ios) {` |
-| `'conditions': [['chromeos==1', {` | `if (is_chromeos) {` |
-
-## Typical sources and deps modifications
-
-### GYP
-
-```
-'sources': [
- 'a.cc',
- 'b.cc',
- 'c.cc',
-],
-'dependencies': [
- '<(DEPTH)/base/base.gyp:foo',
-],
-'conditions': [
- ['OS=="win"': {
- 'sources!': [
- 'a.cc',
- ],
- 'sources': [
- 'foo.cc',
- ],
- 'dependencies': [
- '<(DEPTH)/base/base.gyp:bar',
- ],
- }, {
- 'sources/': [
- ['exclude', '^b\\.cc$'],
- ],
- }],
-],
-```
-
-### GN
-
-```
-sources = [
- "c.cc",
-]
-deps = [
- "//base:foo",
-]
-
-if (is_win) {
- sources += [
- "b.cc",
- "foo.cc',
- ]
- deps += [ "//base:bar" ]
-} else {
- sources += [ "a.cc" ]
-}
-```
-
-Note that in GN we prefer to only add files when needed, and don't add all of
-them at first only to remove them later like in gyp.
-
-## Variable mappings
-
-### Build configuration
-
-Build configuration and feature flags are usually global in GYP. In GN
-we try to limit global variables and instead put variables used by only
-some files into `.gni` files. These files are then imported into your
-buildfile by specifying at the top:
-
-```
-import("//build/config/features.gni")
-
-# ... now you can use the variables declared in features.gni.
-if (is_tsan) {
- # ...
-}
-if (cld_version == 2) {
- # ...
-}
-```
-
-Other flags only apply to one `BUILD.gn` file and those flags are
-declared directly in that file (so other files can't use them). These
-places are noted in the table below.
-
-| *GYP* | *GN* | *GN import* |
-|:------------------------------------------------|:-------------------------------------------|:-----------------------------------------------|
-| `arm_float_abi` | `arm_float_abi` | `//build/config/arm.gni` |
-| `arm_neon` (0/1) | `arm_use_neon` (true/false) | `//build/config/arm.gni` |
-| `arm_neon_optional` (0/1) | `arm_optionally_use_neon` (true/false) | `//build/config/arm.gni` |
-| `arm_version` | `arm_version` | `//build/config/arm.gni` |
-| `asan` (0/1) | `is_asan` (true/false) | `//build/config/sanitizers/sanitizers.gni` |
-| `branding` ("Chromium"/"Chrome") | `is_chrome_branded` (true/false) | `//build/config/chrome_build.gni` |
-| `build_for_tool=="tsan"` | `enable_iterator_debugging=false` | (internal to `//build/config/BUILD.gn`) |
-| `buildtype` ("Official"/"Dev") | `is_official_build` (true/false) | `//build/config/chrome_build.gni` |
-| `chrome_multiple_dll` (0/1) | `is_multi_dll_chrome` (true/false) | `//build/config/chrome_build.gni` |
-| `clang` (0/1) | `is_clang` (true/false) | (global) |
-| `clang_use_chrome_plugins` (0/1) | `clang_use_chrome_plugins` (true/false) | (internal to `//build/config/clang/BUILD.gn`) |
-| `component` ("shared_library"/"static_library") | `is_component_build` (true/false) | (global) |
-| `desktop_linux` (0/1) | `is_desktop_linux` (true/false) | (global) |
-| `disable_glibcxx_debug` (0/1) | `enable_iterator_debugging` (true/false) | (internal to `//build/config/BUILD.gn`) |
-| `fastbuild` (0/1/2) | `symbol_level` (2/1/0 — values inverted) | `//build/config/compiler/compiler.gni` |
-| `gomadir` | `goma_dir` | `//build/toolchain/goma.gni` |
-| `ios_deployment_target` (string) | `ios_deployment_target` | `//build/config/ios/ios_sdk.gni` |
-| `GYP_MSVS_OVERRIDE_PATH` environment variable | `visual_studio_path` | `//build/config/win/visual_studio_version.gni` |
-| `GYP_MSVS_VERSION` environment variable | (none) | |
-| `ios_sdk_path` | `ios_sdk_path` and `use_ios_simulator` | `//build/config/ios/ios_sdk.gni` |
-| `lsan` (0/1) | `is_lsan` (true/false) | `//build/config/sanitizers/sanitizers.gni` |
-| `mac_sdk_min` | `mac_sdk_min` | `//build/config/mac/mac_sdk.gni` |
-| `mac_sdk_path` | `mac_sdk_path` | `//build/config/mac/mac_sdk.gni` |
-| `mac_sdk` | `mac_sdk_version` | `//build/config/mac/mac_sdk.gni` |
-| `mac_strip_release` | `enable_stripping` | `//build/config/mac/symbols.gni` |
-| `mac_want_real_dsym` | `enable_dsyms` | `//build/config/mac/symbols.gni` |
-| `msan` (0/1) | `is_msan` (true/false) | `//build/config/sanitizers/sanitizers.gni` |
-| `SDKROOT` (Mac) | `sysroot` | `//build/config/sysroot.gni` |
-| `sysroot` | `sysroot` | `//build/config/sysroot.gni` |
-| `target_arch` ("ia32"/"x64"/"arm"/"mipsel") | `target_cpu` ("x86"/"x64"/"arm"/"mipsel") | (global) |
-| `toolkit_views` (0/1) | `toolkit_views` | `//build/config/ui.gni` |
-| `tsan` (0/1) | `is_tsan` (true/false) | `//build/config/sanitizers/sanitizers.gni` |
-| `windows_sdk_path` | `windows_sdk_path` | (internal to `//build/config/win/BUILD.gn`) |
-
-### Feature flags
-
-| *GYP* | *GN* | *GN import* |
-|:----------------------------------------|:-----------------------------------------------|:------------------------------|
-| `cld_version` (number) | `cld_version` (number) | `//build/config/features.gni` |
-| `configuration_policy` (0/1) | `enable_configuration_policy` (true/false) | `//build/config/features.gni` |
-| `debug_devtools` (0/1) | `debug_devtools` (true/false) | `//build/config/features.gni` |
-| `disable_ftp_support` (0/1) | `disable_ftp_support` (true/false) | `//build/config/features.gni` |
-| `disable_nacl` (0/1) | `enable_nacl` (true/false) | `//build/config/features.gni` |
-| `enable_app_list` (0/1) | `enable_app_list` (true/false) | `//build/config/features.gni` |
-| `enable_autofill_dialog` (0/1) | `enable_autofill_dialog` (true/false) | `//build/config/features.gni` |
-| `enable_background` (0/1) | `enable_background` (true/false) | `//build/config/features.gni` |
-| `enable_captive_portal_detection` (0/1) | `enable_captive_portal_detection` (true/false) | `//build/config/features.gni` |
-| `enable_chromevox_next` (0/1) | `enable_chromevox_next` (true/false) | `//build/config/features.gni` |
-| `enable_extensions` (0/1) | `enable_extensions` (true/false) | `//build/config/features.gni` |
-| `enable_google_now` (0/1) | `enable_google_now` (true/false) | `//build/config/features.gni` |
-| `enable_hidpi` (0/1) | `enable_hidpi` (true/false) | `//ui/base/ui_features.gni` |
-| `enable_managed_users` (0/1) | `enable_managed_users` (true/false) | `//build/config/features.gni` |
-| `enable_mdns` (0/1) | `enable_mdns` (true/false) | `//build/config/features.gni` |
-| `enable_one_click_signin` (0/1) | `enable_one_click_signin` (true/false) | `//chrome/common/features.gni` |
-| `enable_pepper_cdms` (0/1) | `enable_pepper_cdms` (true/false) | `//ppapi/features/features.gni` |
-| `enable_plugins` (0/1) | `enable_plugins` (true/false) | `//build/config/features.gni` |
-| `enable_plugin_installation` (0/1) | `enable_plugin_installation` (true/false) | `//build/config/features.gni` |
-| `enable_basic_printing` (0/1) | `enable_basic_printing` (true/false) | `//build/config/features.gni` |
-| `enable_print_preview` (0/1) | `enable_print_preview` (true/false) | `//build/config/features.gni` |
-| `enable_rlz` (0/1) | `enable_rlz` (true/false) | `//build/config/features.gni` |
-| `enable_spellcheck` (0/1) | `enable_spellcheck` (true/false) | `//build/config/features.gni` |
-| `enable_session_service` (0/1) | `enable_session_service` (true/false) | `//build/config/features.gni` |
-| `enable_task_manager` (0/1) | `enable_task_manager` (true/false) | `//build/config/features.gni` |
-| `enable_themes` (0/1) | `enable_themes` (true/false) | `//build/config/features.gni` |
-| `enable_webrtc` (0/1) | `enable_webrtc` (true/false) | `//build/config/features.gni` |
-| `image_loader_extension` (0/1) | `enable_image_loader_extension` (true/false) | `//build/config/features.gni` |
-| `input_speech` (0/1) | `enable_speech_input` (true/false) | `//build/config/features.gni` |
-| `notifications` (0/1) | `enable_notifications` (true/false) | `//build/config/features.gni` |
-| `ozone_platform_dri` (0/1) | `ozone_platform_dri` (true/false) | `//build/config/ui.gni` |
-| `remoting` (0/1) | `enable_remoting` (true/false) | `//build/config/features.gni` |
-| `safe_browsing` (0/1/2) | `safe_browsing_mode` (0/1/2) | `//build/config/features.gni` |
-| `use_allocator` (`'none'`|`'tcmalloc'`) | `use_allocator` (`"none"`|`"tcmalloc"`) | (See "Allocator" below) |
-| `ui_compositor_image_transport` (0/1) | `ui_compositor_image_transport` (true/false) | `//build/config/ui.gni` |
-| `use_ash` (0/1) | `use_ash` (true/false) | `//build/config/ui.gni` |
-| `use_athena` (0/1) | `use_athena` (true/false) | `//build/config/ui.gni` |
-| `use_aura` (0/1) | `use_aura` (true/false) | `//build/config/ui.gni` |
-| `use_cairo` (0/1) | `use_cairo` (true/false) | `//build/config/ui.gni` |
-| `use_cups` (0/1) | `use_cups` (true/false) | `//build/config/features.gni` |
-| `use_dbus` (0/1) | `use_dbus` (true/false) | `//build/config/features.gni` |
-| `use_gconf` (0/1) | `use_gconf` (true/false) | `//build/config/features.gni` |
-| `use_glib` (0/1) | `is_linux` (true/false) | (global) |
-| `use_gnome_keyring` (0/1) | `use_gnome_keyring` (true/false) | |
-| `use_goma` (0/1) | `use_goma` (true/false) | `//build/toolchain/goma.gni` |
-| `use_nss_certs` (0/1) | `use_nss_certs` (true/false) | `//build/config/crypto.gni` (Many of these conditions can be deleted, see the "SSL" notes on targets below.) |
-| `use_pango` (0/1) | `use_pango` (true/false) | `//build/config/ui.gni` |
-| `use_ozone` (0/1) | `use_ozone` (true/false) | `//build/config/ui.gni` |
-| `use_seccomp_bpf` (0/1) | `use_seccomp_bpf` (true/false) | `//build/config/features.gni` |
-| `use_udev` (0/1) | `use_udev` (true/false) | `//build/config/features.gni` |
-| `use_x11` (0/1) | `use_x11` (true/false) | `//build/config/ui.gni` |
-| `use_xi2_mt` (0/1) | `use_xi2_mt` (true/false) | `//build/config/ui.gni` |
-| `win_use_allocator_shim` (0/1) | | (See "Allocator" below) |
-
-### Common target conversion
-
-Some targets that lots of projects depend on and how the GN ones
-correspond to GYP ones. (This is for commonly-depended-on or weird
-targets only, don't add stuff here just because you converted it.)
-
-| *GYP* | *GN* | *Notes* (see below) |
-|:-----------------------------------------------------------------------------------|:-----------------------------------------|:---------------------|
-| `base/base.gyp:base` | `//base` | |
-| `base/base.gyp:base_i18n` | `//base:i18n` | |
-| `base/base.gyp:run_all_unittests` | `//base/test:run_all_unittests` | |
-| `base/base.gyp:test_support_base` | `//base/test:test_support` | |
-| `base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations` | `//base/third_party/dynamic_annotations` | |
-| `build/linux/system.gyp:*` (except nss) | `//build/config/linux:*` | Linux system targets |
-| `build/linux/system.gyp:nss` | `//crypto:platform` | SSL |
-| `net/third_party/nss/ssl.gyp:libssl` | `//crypto:platform` | SSL |
-| `skia/skia.gyp:skia` | `//skia` | |
-| `testing/gmock.gyp:gmock` | `//testing/gmock` | Secondary tree |
-| `testing/gtest.gyp:gtest` | `//testing/gtest` | Secondary treeo |
-| `third_party/icu/icu.gyp:icui18n` | `//third_party/icu` | Secondary tree, ICU |
-| `third_party/icu/icu.gyp:icuuc` | `//third_party/icu` | Secondary tree, ICU |
-| `url/url.gyp:url_lib` | `//url` || ||
-
-Notes:
-
- * *ICU:* GN has separate `//third_party/icu:icuuc` and
- `//third_party/icu:icui18n` targets just like GYP. You can use these
- if you only need one of them. Most targets want both, so GN made a
- meta target that's just `//third_party/icu` which you can use that
- redirects to both "uc" and "i18n".
-
- * *Linux system targets:* Generally the names in GN patch the GYP
- names for the Linux system-related stuff. However, most of them are
- configs instead of actual targets (in GYP they're all targets). For
- example, since "x11" is just a list of libraries and include
- directories, and includes no sources it's a config that just adds
- this configuration to your target. To use a config, do `configs += [
- "//build/config/linux:x11" ]`
-
- * *Secondary tree:* Some projects are DEPSed in and we want it to look
- like a BUILD.gn file is in that directory without checking it in to
- the upstream repo. The directory `build/secondary` mirrors the main
- tree and is checked for BUILD.gn files if an expected file in the
- main tree wasn't found.
-
- * *SSL:* In GYP there are lots of conditions around NSS vs. OpenSSL
- and different platforms that determine which of the different SSL
- libraries is linked. In GN, there is a meta-target
- `//crypto:platform` that will "do the right thing" according to the
- current build platform and flags. Generally its safe to replace any
- conditional reference to a SSL library with this one.
-
-## Visibility and header file issues
-
-GN is much more strict about header file checking. You may encounter
-errors that your target doesn't depend on the target containing a
-certain header file. The most common example is including
-`base/macros.h` without having `//base` in your project's dependency
-list. The solution is to just add the missing dependency.
-
-The dependency tree must be a DAG. Some components might share headers
-between a number of internal targets that makes adding the "proper"
-dependencies impossible. In this case, you can separate out a
-`source_set` type target containing just the header(s) in question, and
-make the targets that use that header depend on that source set to break
-the cycle.
-
-## Other stuff
-
-### Target conditions
-
-`target_conditions` are like normal conditions but expanded in a
-different phase of GYP. You can generally just convert the conditions
-inside and not worry about the `conditions`/`target_conditions`
-difference.
-
-### xcode_settings
-
-Some xcode settings are obvious:
-
-```
- 'xcode_settings': {'OTHER_LDFLAGS': ['-foo']},
-```
-
-Should just expand to:
-
-```
- ldflags = [ "-foo" ]
-```
-
-Other flags are less obvious:
-
-```
- 'xcode_settings': { 'GCC_SYMBOLS_PRIVATE_EXTERN': 'NO', },
-```
-
-These all correspond to various flags that get passed to the compiler or
-linker. You can use your favorite search engine to see what it
-corresponds to, but many of them are not well documented. You can also
-search for the string in
-[tools/gyp/pylib/gyp/xcode_emulation.py](https://code.google.com/p/chromium/codesearch#chromium/src/tools/gyp/pylib/gyp/xcode_emulation.py). GYP uses this file to decode
-the Xcode settings into command line flags for the ninja build.
-
-### wexit-time destructors
-
-Replace
-
-```
-'enable_wexit_time_destructors': 1,
-```
-
-with
-
-```
-configs += [ "//build/config/compiler:wexit_time_destructors" ]
-```
-
-### Chromium code
-
-In GYP code is "non-Chromium" by default, and you opt into higher warning levels using:
-
-```
-'chromium_code': 1,
-```
-
-In GN, all code is Chromium code by default. If you're compiling a
-static library that needs more lax warnings, opt out of the
-Chromium-code settings with:
-
-```
-configs -= [ "//build/config/compiler:chromium_code" ]
-configs += [ "//build/config/compiler:no_chromium_code" ]
-```
-
-### -fvisibility
-
-All symbols in the build have "hidden" visibility by default (this means
-that symbols aren't exported from shared libraries, a concept different
-than GN's target visibility). If you needed to export all symbols (for a
-third party library) by default in GYP you would do:
-
-```
-'xcode_settings': [
- 'GCC_SYMBOLS_PRIVATE_EXTERN': 'NO', # no -fvisibility=hidden
-],
-'cflags!': [
- '-fvisibility=hidden',
-],
-```
-
-In GN the equivalent is:
-
-```
-if (!is_win) {
- configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
-}
-```
-
-### Dependent settings
-
-In GYP you'll see stuff like this, especially in third-party code.
-
-```
-'direct_dependent_settings': {
- 'include_dirs': [
- '.', # This directory.
- '../..', # Root "src" path.
- ],
- 'defines': [
- 'FOO',
- ],
-},
-```
-
-Note that many of the includes are trying to add the root "src"
-directory to the include path. This is always present in GN so you can
-remove these.
-
-GYP also requires you to duplicate these settings, once for the target
-itself, and once for the direct/all dependent settings. In GN,
-public/all dependent configs also apply to the current target so you
-only need to specify it once.
-
-In GN, put the settings in a config (declared above your target), and
-then reference that as a public config in your target:
-
-```
-config("foo_config") {
- include_dirs = [ "." ]
- defines = [ "FOO" ]
-}
-
-component("foo") {
- ...
- public_configs = [ ":foo_config" ]
-}
-```
-
-Targets that depend on `foo` will now get `foo_config` applied.
-
-GYP would say `export_dependent_settings` to forward
-`direct_dependent_settings` up the dependency chain. In GN, put the
-dependency in the `public_deps` section and this will happen
-automatically.
-
-### MSVS disabled warnings
-
-In GYP you'll see for third-party code:
-
-```
-'msvs_disabled_warnings': [ 4018, 4244, 4267, ],
-```
-
-At least half of the warnings in these blocks are already disabled
-globally (we added more global ones later). From the command line, do:
-
-```
-$ cd src/build/config
-$ git grep 4018
-compiler/BUILD.gn: "/wd4018", # Comparing signed and unsigned values.
-```
-
-tells us that warning 4018 is already disabled globally from the
-`default_warning_flags` variable in `//build/config/compiler`, and the same
-for 4244. So ignore these.
-
-Always comment what the warning is. Use your favorite search engine and
-type "vc warning 4267" to look it up. You'll end up with:
-
-```
-if (is_win) {
- cflags += [
- "/wd4267", # Conversion from size_t to 'type'.
- ]
-}
-```
-
-(Use `=` instead of `+=` is you haven't already defined a `cflags` variable.)
-
-### Mac frameworks
-
-GN knows to convert `.framework` files in the `libs` list to the right
-thing on Mac. You don't need to specify the directories either. So
-convert this:
-
-```
-'link_settings': {
- 'libraries': [
- '$(SDKROOT)/System/Library/Frameworks/Accelerate.framework',
- ],
-},
-```
-
-to this:
-
-```
-libs = [ "Accelerate.framework" ]
-```
-
-### hard_dependency
-
-GYP code sometimes sets
-
-```
- 'hard_dependency': 1,
-```
-
-to indicate that the current target must be build before its dependents.
-GN can deduce this internally, so you can ignore this directive.
-
-### Allocator
-
-GYP has `win_use_allocator_shim` and `use_allocator`. In GN, these are
-merged into `use_allocator` which is defined in
-`//build/config/allocator.gni`. _However_ you should almost never need
-to use this flag. The `//base/allocator` target will change depending on
-the current allocator flag, so you can unconditionally depend on this
-target to pick up the current build defaults.
-
-This:
-
-```
- ['use_allocator!='none'', {
- 'dependencies': [ '../base/allocator/allocator.gyp:allocator' ]
- }],
- ['win_use_allocator_shim==1', {
- 'dependencies': [ '<(allocator_target)' ],
- }],
-```
-
-Becomes:
-
-```
- deps = [ "//base/allocator" ]
-```
-
-As in GYP, the allocator should only be depended on by executables (and
-tests). Libraries should not set the allocator.
-
-### optimize: max
-
-In Gyp:
-
-```
-'optimize': 'max',
-```
-
-only affects Windows and will optimize for speed rather than size. To
-get the same behavior in GN, do:
-
-```
-if (!is_debug && is_win) {
- configs -= [ "//build/config/compiler:default_optimization" ]
- configs += [ "//build/config/compiler:optimize_max" ]
-}
-```
-
-The `is_win` check is needed because the `optimize_max` config also
-affects Posix systems. Some components might additionally specify `-O2`
-on Posix further optimize, in which case you can remove the `is_win`
-check.
-
-### Protobufs
-
-```
-import("//third_party/protobuf/proto_library.gni")
-
-proto_library("myproto") {
- sources = [ "foo.proto" ]
-}
-```
-
-See the `third_party/protobuf/proto_library.gni` file for full
-documentation and extra flags.
-
-### Java stuff
-
-JNI generator in GYP:
-
-```
-{
- 'target_name': 'foo_headers',
- 'type': 'none',
- 'sources': [ <java files> ]
- 'variables': { 'jni_gen_package': 'foobar' }
- 'includes': [ 'build/jni_generator.gypi' ]
-}
-```
-
-JNI generator in GN:
-
-```
-# At top of file:
-if (is_android) {
- import("//build/config/android/rules.gni")
-}
-
-# Later:
-if (is_android) {
- generate_jni("foo_headers") {
- sources = [ <java files> ]
- jni_package = "foobar"
- }
-}
-```
-
-### Grit
-
-```
-import("//tools/grit/grit_rule.gni")
-
-grit("resources") {
- source = "my_resources.grd"
-}
-```
-
-See `src/build/secondary/tools/grit/grit_rule.gni` for more documentation.
-
-### Mojo
-
-```
-import("//mojo/public/tools/bindings/mojom.gni")
-
-mojom("mojo_bindings") {
- sources = [
- "foo.mojom",
- ]
-}
-```
