Substitution issue for -L in Makefile.PL on HPUX

[maxvohlkenhcl]

On HPUX the platform identifier is IA64.ARCHREV_0-thread-multi-LP64. A substitution for -L in the Makefile.PL incorrectly replaces the -L in -LP64 when the platform identifier is on the linker command line. An example is the -Wl,+b/usr/lib/perl5/5.26.3/IA64.ARCHREV_0-thread-multi-LP64/CORE option to add the CORE directory to the embedded runpath.

The offending line is:
($args{uc $_} = $Config{$_}) =~ s/-L/$lp -L/ for qw(lddlflags ldflags);
The s/-L/ isn't specific enough. The desire is to match the -L linker argument. So a better match is to look for -L after a space or at the beginning of the value. So I propose this improvement.
($args{uc $_} = $Config{$_}) =~ s/(^|\s)-L/$1$lp -L/ for qw(lddlflags ldflags);

[h-vn]

Looks good. I first thought about removing the match variable $1 and using non-capturing grouping (?:...) but that would not preserve space and would cause a problem.

[maxvohlkenhcl]

It looks like you figured out that the (?:^|\s) would match a space but it would not restore it in the result. I think what you are thinking of is the zero-width positive lookbehind assertion syntax. "(?<=pattern)" "\K" A zero-width positive lookbehind assertion. For example, "/(?<=\t)\w+/" matches a word that follows a tab, without including the tab in $&. Works only for fixed-width lookbehind. There is a special form of this construct, called "\K" (available since Perl 5.10.0), which causes the regex engine to "keep" everything it had matched prior to the "\K" and not include it in $&. This effectively provides variable-length lookbehind. The use of "\K" inside of another lookaround assertion is allowed, but the behaviour is currently not well defined. For various reasons "\K" may be significantly more efficient than the equivalent "(?<=...)" construct, and it is especially useful in situations where you want to efficiently remove something following something else in a string. For instance s/(foo)bar/$1/g; can be rewritten as the much more efficient s/foo\Kbar//g; I wasn't sure how well this worked with matching the beginning of the string so I opted for what I knew worked. So it looks like we just need to add the \K to your version. ($args{uc $_} = $Config{$_}) =~ s/(?:^|\s)\K-L/$lp -L/ for qw(lddlflags ldflags); Yup it works too: $ perl -e ***@***.***) { print "$_\n"; s/(?:^|\s)\K-L/-LBBB -L/g; print "$_\n"; }' -- '-La-LP64 -Lc -Ld-LP64' -La-LP64 -Lc -Ld-LP64 -LBBB -La-LP64 -LBBB -Lc -LBBB -Ld-LP64 Max Vohlken (he/him) Senior Software Engineer ClearCase/VersionVault and ClearQuest/Compass HCLSoftware <https://hcl-software.com/> Ardsley, New York ***@***.*** Mobile: +1-781-640-2170

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On Mon, Dec 2, 2024 at 11:44 AM Heikki Vatiainen ***@***.***> wrote: Here's one more improvement that adds non-capturing match with ?:: ($args{uc $_} = $Config{$_}) =~ s/(?:^|\s)-L/$lp -L/ for qw(lddlflags ldflags); As far as I can tell, it does the same thing but without capture or capture variable $1. Does the above work for you too? — Reply to this email directly, view it on GitHub <#492 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AIZRVGFUNGZ446JFHEGYM632DSE7DAVCNFSM6AAAAABSBBKSJWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKMJSGEYDKMRRGY> . You are receiving this because you authored the thread.Message ID: ***@***.***>