Fix build failures of new APIs on old macOS SDK
New APIs supported from macOS 11.0 cannot build successfully on macOS
10.15, even use @available to control whether a declaration is
available on target platform, but does not work in conditionally
compiling.
Update building.md to require the macOS 11.0 SDK.
Bug: dawn:1054
Change-Id: If22ada959c0c1ef41826f78bd337b912772000b1
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/61021
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
diff --git a/docs/building.md b/docs/building.md
index 60b618c..230c222 100644
--- a/docs/building.md
+++ b/docs/building.md
@@ -1,16 +1,28 @@
# Building Dawn
+## System requirements
+
+- Linux
+ - The `pkg-config` command:
+ ```sh
+ # Install pkg-config on Ubuntu
+ sudo apt-get install pkg-config
+ ```
+
+- Mac
+ - [Xcode](https://developer.apple.com/xcode/) 12.2+.
+ - The macOS 11.0 SDK. Run `xcode-select` to check whether you have it.
+ ```sh
+ ls `xcode-select -p`/Platforms/MacOSX.platform/Developer/SDKs
+ ```
+
+## Install `depot_tools`
+
Dawn uses the Chromium build system and dependency management so you need to [install depot_tools] and add it to the PATH.
[install depot_tools]: http://commondatastorage.googleapis.com/chrome-infra-docs/flat/depot_tools/docs/html/depot_tools_tutorial.html#_setting_up
-On Linux you need to have the `pkg-config` command:
-```sh
-# Install pkg-config on Ubuntu
-sudo apt-get install pkg-config
-```
-
-Then get the source as follows:
+## Get the code
```sh
# Clone the repo as "dawn"
@@ -23,6 +35,8 @@
gclient sync
```
+## Build Dawn
+
Then generate build files using `gn args out/Debug` or `gn args out/Release`.
A text editor will appear asking build options, the most common option is `is_debug=true/false`; otherwise `gn args out/Release --list` shows all the possible options.