GNU patch < 2.7.6 doesn't apply executable bit correctly

[dra27]

Found while investigating build failures ocaml/opam-repository#12674

Versions of patch prior to 2.7.6 (includes Debian 9) don't set the executable bit on new files when reading a git patch (see http://git.savannah.gnu.org/cgit/patch.git/commit/?id=592e1f9163d6261359aa87c2c99d411c0dacf6f3)

This causes new executable files to lose the +x bit when copied from the Git clone to .opam/repo/...

2.7.6. is the very latest release of GNU patch - I expect the solution to this will be to post-process and check the permissions.

[AltGr]

One more reason to reimplement our own patch handling :)

[dra27]

Indeed!

[rjbou]

cf. https://github.com/hannesm/patch

[dra27]

Cool - it would need extending to parse Git headers... to be honest, it would probably want extending line-by-line against GNU patch 🤦‍♂️

[hannesm]

the patch is atm mainly code extracted from conex (where, due to dependencies, and being able to cope with non-unix systems, I don't call out to patch). for that, I don't have the need for "parse git headers" or similar features (which does not mean that that should not be added, just that I won't spend much time on it). the scope is also only to handle unified diffs (atm even ignoring merge conflicts) -- if the diff does not apply cleanly, this should result in an error state (but iirc atm its accepted).

@dra27 I don't understand what you mean by "it would probably want extending line-by-line against GNU patch"

[dra27]

@hannesm - I mean that patch is so well-specified that it’ll probably need someone to go through its code and reverse-engineer the precise behaviours which want adding

[kit-ty-kate]

I got bitten by this again in ocaml/opam-repository#18064
I'll make the opam-repo-ci linter fail if this case is encountered (ocurrent/opam-repo-ci#74) but this is still quite annoying