make tests pass when build directory name contains @ $ \ "

[mauke]

If you build and test perl from a directory whose name contains an @ sign (such as /tmp/hello@world/perl5), one of the tests in t/io/pipe.t fails.

This is because it takes the path to the perl binary (which is /tmp/hello@world/perl5/perl in our example) and interpolates it in double-quotes into a string that is then eval'd and run (via fresh_perl()). Thus the code that the interpreter in the child process sees is:

$Perl = "/tmp/hello@world/perl5/perl";

which of course tries to interpolate the (non-existent) @world array. (Similar problems would be caused by paths containing $ or " characters).

Switching to single quotes, as in

$Perl = '/tmp/hello@world/perl5/perl';

would fix this case, but would still be vulnerable to a path containing ' symbols.

Sidestep the problem by using q (to prevent variable interpolation) with a NUL byte delimiter (which cannot occur in path names).

Found while investigating #22446.

[jkeenan]

Problem confirmed.

$ pwd
/home/jkeenan/tmp/gh-22449/hello@world
[hello@world] 2009 $ cd t;./perl harness io/pipe.t; cd -
io/pipe.t .. 14/27 # Failed test 27 - but we did get the exception from die at io/pipe.t line 272
#      got "sh: 1: /home/jkeenan/tmp/gh-22449/hello/perl: not found"
# expected =~ "(?^:Died at)"
io/pipe.t .. Failed 1/27 subtests 

Test Summary Report
-------------------
io/pipe.t (Wstat: 0 Tests: 27 Failed: 1)
  Failed test:  27
Files=1, Tests=27,  8 wallclock secs ( 0.01 usr  0.00 sys +  0.03 cusr  0.01 csys =  0.05 CPU)
Result: FAIL
Finished test run at Tue Jul 30 15:57:01 2024.
/home/jkeenan/tmp/gh-22449/hello@world

Separately confirmed that p.r. works.