[PATCH v2 0/2] add and apply a rule to find "unused" init+free

This re-roll of [1] gets to the same end-state as far as the changed C code is concerned, but I rewrote the coccinelle rule to be much more general, based on the more recent discussion at [2].

See the "contrib/coccinelle/unused.cocci" part of 1/2 for extensive commentary and what the rule does & doesn't spot, which I won't repeat here.

The 2/2 is then split up to show the effect that "when strict" has on this.

I noted in [2] that I had a WIP rule to to remove that unused "get_worktrees()" but couldn't figure out a bug, this coccinelle code will properly remove that sort of code, but only if it's actually unused.

1. https://lore.kernel.org/git/patch-1.1-7d90f26b73f-20220520T115426Z-avarab@gmail.com/
2. https://lore.kernel.org/git/220620.865ykvw2l4.gmgdl@evledraar.gmail.com/

Ævar Arnfjörð Bjarmason (2):
  cocci: add and apply a rule to find "unused" variables
  cocci: remove "when strict" from unused.cocci

 builtin/fetch.c                 |  3 +-
 builtin/merge.c                 |  4 ---
 builtin/repack.c                |  2 --
 contrib/coccinelle/unused.cocci | 64 +++++++++++++++++++++++++++++++++
 contrib/scalar/scalar.c         |  3 +-
 diff.c                          |  2 --
 6 files changed, 66 insertions(+), 12 deletions(-)
 create mode 100644 contrib/coccinelle/unused.cocci

Range-diff against v1: 1: 7d90f26b73f < -: ----------- cocci: add and apply a rule to find "unused" variables -: ----------- > 1: d14036521ab cocci: add and apply a rule to find "unused" variables -: ----------- > 2: 4130dc15287 cocci: remove "when strict" from unused.cocci