Hi Karl, Sorry to cause you grief, but...
On Wed, Sep 7, 2022 at 7:49 PM Karl Berry <k...@freefriends.org> wrote: > > [ef]grep > > I guess my basic issue is that I don't understand the benefit of the new > warning. It causes a lot of trouble. What is the countervailing > positive benefit? Some must care about portability, and these warnings help them do a better job. As Gary mentioned above, it's easy to disable them. > $ grep '\Q' /dev/null > grep: warning: stray \ before Q > It would be nice to be able to turn those off too. (It hit me today.) I would argue that it is even more important to retain these stray-backslash warnings, because they tend to highlight real bugs. Consider these uses of \d: $ echo d | grep-3.7 '\d' d $ echo d | grep-3.8 '\d' grep: warning: stray \ before d Anyone used to PCRE regexps (who isn't, these days) knows that its "\d" is intended to match a digit, not the letter "d". With grep-3.7, you'd get misbehavior and no warning about your error. With grep-3.8, you'll get the diagnostic and maybe switch to using "grep -P", where "\d" works as expected -- switching from \d to [0-9] hurts readability and feels like dumbing-down, especially when there are two or more \d uses. Using PCRE's \Q...\E groups *without -P* is another issue that is now diagnosed. For example, the following upstream projects have misuses of grep that are exposed by running this: git grep 'grep .*\\[dQE]' | grep -ve '-[[:alnum:]]*P' - linux scripts/checkpatch.pl: `grep -Eq "\\"\\^\Q$vendor\E,\\.\\*\\":" $vp_file`; - gcc libgo/go/cmd/go/testdata/script/mod_get_lazy_indirect.txt:grep 'rsc.io/quote v\d+\.\d+\.\d+ // indirect$' go.mod libgo/go/cmd/go/testdata/script/mod_get_lazy_indirect.txt:! grep 'rsc.io/quote v\d+\.\d+\.\d+$' go.mod libgo/go/cmd/go/testdata/script/mod_get_lazy_indirect.txt:grep 'rsc.io/quote v\d+\.\d+\.\d+$' go.mod libgo/go/cmd/go/testdata/script/mod_get_lazy_indirect.txt:! grep 'rsc.io/quote v\d+\.\d+\.\d+ // indirect$' go.mod
