[PATCH 0/6] Makefile: make non-symlink & non-hardlink install sane

This is on top of my just-submitted "Makefile: don't die on AIX with open ./git" series: [1]

This series introduces no "real" behavior changes I'd expect anyone to notice, but refactors a lengthy copy/pasted test/if/else in the Makefile into a simple helper script.

The "real" behavior change is that we no longer ask the user how they'd like to install (symlinks, hardlinks, neither?) and then proceed to ignore what was asked of us and optimistically fallback in case of errors. I.e. the inability to create symlinks or hardlinks.

Instead we'll just die, the old behavior is still available as INSTALL_FALLBACK_LN_CP. In practice I think exactly nobody actually wanted the existing behavior.

It's just something that emerged over almost 2 decades of first wanting to have the ability to specify such a fallback, and then adding e.g. support for INSTALL_SYMLINKS along the way.

There's also side-discussion of a bug I discovered along the way in SKIP_DASHED_BUILT_INS in 4/6. This series doesn't make that bug better or worse, but it interacts with the flags being changed here.

1. https://lore.kernel.org/git/cover-0.6-00000000000-20210329T161723Z-avarab@gmail.com/
   In practice they apply independently, but since they're touching
   some very adjacent code I'm saying it's "on top" in case a re-roll
   makes it so, and also for ease of local testing.

   I'm trying a new thing of splitting my serieses up a bit, so if
   there's outstanding feedback on the later parts, hopefully the
   former part can proceed independently...

Ævar Arnfjörð Bjarmason (6):
  Makefile: symlink the same way under "symlinks" and "no hardlinks"
  Makefile: begin refactoring out "ln || ln -s || cp" pattern
  Makefile: refactor out "ln || ln -s || cp" pattern
  Makefile: make INSTALL_SYMLINKS affect the build directory
  Makefile: use "ln -f" instead of "rm && ln"
  Makefile: add a INSTALL_FALLBACK_LN_CP mode

 .gitignore  |  1 +
 Makefile    | 91 +++++++++++++++++++++++++++++++----------------------
 ln-or-cp.sh | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 145 insertions(+), 38 deletions(-)
 create mode 100755 ln-or-cp.sh