rewriter: create {add,rm}_extra_files commands

Add ability to mutate a target's `extra_files` list through the
rewriter.

The logic is copied from sources add/rm, but changes the `extra_files`
kwarg instead of the sources positional argument.
Has additional logic to handle creating the `extra_files` list if it
doesn't exist.

1 files changed, 26 insertions, 0 deletions

diff --git a/docs/markdown/snippets/rewriter_extra_files.md b/docs/markdown/snippets/rewriter_extra_files.md
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index 0000000..c46f076
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+## `meson rewrite` can modify `extra_files`
+
+The build script rewriter can now modify targets' `extra_files` lists,
+or create them if absent. It it used in the same way as with rewriting
+source lists:
+
+```bash
+meson rewrite target <target name/id> {add_extra_files/rm_extra_files} [list of extra files]
+```
+
+The rewriter's script mode also supports these actions:
+
+```json
+{
+  "type": "target",
+  "target": "<target name>",
+  "operation": "extra_files_add / extra_files_rm",
+  "sources": ["list", "of", "extra", "files", "to", "add, remove"],
+}
+```
+
+## `meson rewrite target <target> info` outputs *target*'s `extra_files`
+
+Targets' `extra_files` lists are now included in the rewriter's target info dump
+as a list of file paths, in the same way `sources` are. This applies to both
+`meson rewrite` CLI and script mode.