XQuartz was the last consumer of this 2007 workaround, which made getDrawableDamageRef() route a non-viewable window's
damage to the screen damage list instead of the window pixmap's. Because the answer then changed as a window's
viewability changed, it was a source of exactly the register/unregister list mismatch the previous commit addresses --
CrushTree() clears ->viewable before unrealizing, so a window's damage was inserted on one list and looked for on
another during teardown.
It was disabled for XWin in 20701522be for breaking Composite and removed entirely in
c89f0521044083a11d538ebfeaabee6fc7fb9a03, but that removal was reverted in de32d4dcf5
after a regression report, pending a proper fix in the damage layer. That fix is now in place, so drop the workaround.
Fixes: https://github.com/XQuartz/XQuartz/issues/406
Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2277>
(cherry picked from commit cfbc5224a6)
(cherry picked from commit 029735e8a254ed2dd5c565878eb946f1ef684fa1)
(cherry picked from commit 0939e0d745c0ee86e603b23b09cac7ea5e632801)
Port notes
----------
This brings our tree in line with xorg/main, where ROOTLESS_WORKAROUND no longer
occurs at all. Jeremy Huddleston removed it there; this is that change, not a new
proposal.
Scope: the define is set only under `if build_rootless`, and build_rootless is set
only for build_xquartz (meson.build). In a normal -Dwerror=true build of this tree the
generated dix-config.h contains no ROOTLESS_WORKAROUND, so the #ifdef block in
miext/damage/damage.c does not compile there. The affected configuration is macOS
XQuartz.
History: the removal was reverted in de32d4dcf5 after a
regression report, pending a proper fix in the damage layer. That fix has since landed
as #3793 ("use drawable pointer instead of list head pointer"), which is what the
original commit message above refers to. Nothing re-established the workaround's
necessity afterwards: it returned in 2019 only because ecf62b7ba6 added the meson build
and carried the define over from configure.ac, without referring to the 2011 report.
Not verified here: that XQuartz on macOS runs without the workaround. applewm is not
available on this Linux host and no CI lane exercises it.
Not a backport candidate: this removes a workaround rather than fixing a defect.
It corrects no crash, no memory error and no security issue, so it must not be
carried to release/25.2, 25.1 or 25.0. Per the backport policy a release branch takes
bugfixes, not cleanups. If a release branch ever needs this, it has to be a deliberate
maintainer decision with its own justification - not a consequence of this port.
dd5edd037b