Before my 20d2a30f8f ("Makefile: replace perl/Makefile.PL with simple
make rules", 2017-12-10) on an OS package that removed the
private-Error.pm copy we carried around manually removing the OS's
Error.pm would yield:
$ git add -p
Can't locate Error.pm in @INC (you may need to install the Error module) [...]
Now, before this change we'll instead emit this more cryptic error:
$ git add -p
BUG: '/usr/share/perl5/Git/FromCPAN' should be a directory! at /usr/share/perl5/Git/Error.pm line 36.
This is a confusing error. Now if the new NO_PERL_CPAN_FALLBACKS
option is specified and we can't find the module we'll instead emit:
$ /tmp/git/bin/git add -p
BUG: The 'Error' module is not here, but NO_PERL_CPAN_FALLBACKS was set!
[...]
Where [...] is the lengthy explanation seen in the change below, which
explains what the potential breakage is, and how to fix it.
The reason for checking @@NO_PERL_CPAN_FALLBACKS@@] against the empty
string in Perl is as opposed to checking for a boolean value is that
that's (as far as I can tell) make's idea of a string that's set, and
e.g. NO_PERL_CPAN_FALLBACKS=0 is enough to set NO_PERL_CPAN_FALLBACKS.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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