Find build-tool installed programs before programs in path

[alt-romes]

We must consider the path to the installed build-tool before the path to existing versions of the build tool in paths such as extra-prog-path or in the system path.

This was previously fixed by #8972 but undone by #9527.

This also renames appendProgramSearchPath to
prependProgramSearchPath to describe correctly what that function does.

Fixes #9756

[alt-romes]

@gbaz here is the fix.

It still needs a test, I'm trying to figure out how to do one for this specifically.

-- We are testing if the build-tools program is found in path before programs e.g. in extra-prog-path or the system path
-- For that, we need
--  * A repo with a build tool that is up to date
--  * An older version of the build tool in the extra-prog-path
--  * A project that requires the more up-to-date version of the build-tool

Happy to take any ideas

[alt-romes]

(BTW I've tested this locally on Andreas' reproducer successfully)

[alt-romes]

Test added, ready to merge.

[alt-romes]

If this should make it back to 3.10 it needs to be backported @Mikolaj @gbaz

[gbaz]

Thank you so much for moving quickly on this. Given how quickly this has been done, and that the only key change is line 1239 of configure.hs, I definitely think we should backport.

[alt-romes]

I've added the comment you requested @gbaz. I'm also going to put forward a backport MR

[Mikolaj]

@backport 3.12

[Mikolaj]

@mergify backport 3.12

[mergify]

backport 3.12

✅ Backports have been created

• #9773 Find build-tool installed programs before programs in path (backport #9762) has been created for branch 3.12

[Mikolaj]

@backport --- apologies, wrong ping, but you must be used to it by now, aren't you? :)