gnome.gtkdoc() always rebuilds

[kelnos]

Describe the bug

Running meson compile or meson install (or the equivalent ninja commands) causes the gtkdoc docs to always be regenerated, regardless of whether or not anything has changed.

To Reproduce

I can try to put together a small reproducer repo, but hopefully this is a known issue, as I believe it even happened with glib/gtk (before they moved to gi-docgen). https://gitlab.xfce.org/xfce/libxfce4windowing/ and https://gitlab.xfce.org/kelnos/libwlembed/ both exhibit the issue.

Expected behavior

gtkdoc documentation should only be rebuilt when one of the input files has changed.

system parameters

• Is this a cross build or just a plain native build (for the same computer)?
  • Native
• what operating system (e.g. MacOS Catalina, Windows 10, CentOS 8.0, Ubuntu 18.04, etc.)
  • Debian testing
• what Python version are you using e.g. 3.8.0
  • 3.11.8
• what meson --version
  • 1.2.3
• what ninja --version if it's a Ninja build
  • 1.11.1

[dcbaker]

Interesting, we do this explicitly, which doesn't seem good.

@xclaesse: I tracked this back to f5da88112667fddb991ee455c051c9453b2542c1, when you converted the gtkdoc method from a run_target to a custom_target. Do you remember why you set this to be always stale?