Allow setting built-in options from cross/native files

This is like the project options, but for meson builtin options.

The only real differences here have to do with the differences between
meson builtin options and project options. Some meson options can be set
on a per-machine basis (build.pkg_config_path vs pkg_config_path) others
can be set on a per-subproject basis, but should inherit the parent
setting.

1 files changed, 16 insertions, 1 deletions

diff --git a/docs/markdown/snippets/project_options_in_machine_files.md b/docs/markdown/snippets/project_options_in_machine_files.md
index 78b129a..8dab951 100644
--- a/docs/markdown/snippets/project_options_in_machine_files.md
+++ b/docs/markdown/snippets/project_options_in_machine_files.md
@@ -1,4 +1,4 @@
-## Project options can be set in native or cross files
+## Project and built-in options can be set in native or cross files
 
 A new set of sections has been added to the cross and native files, `[project
 options]` and `[<subproject_name>:project options]`, where `subproject_name`
@@ -35,3 +35,18 @@ Subproject options are assigned like this:
 [zlib:project options]
 foo = 'some val'
 ```
+
+Additionally meson level options can be set in the same way, using the
+`[built-in options]` section.
+
+```ini
+[built-in options]
+c_std = 'c99'
+```
+
+These options can also be set on a per-subproject basis, although only
+`default_library` and `werror` can currently be set:
+```ini
+[zlib:built-in options]
+default_library = 'static'
+```