Omit duplicate regexps

Do not pass two copies of the same regexp to the
regular-expression engine.  Although the engines should
perform nearly as well even with the copies, in practice they do not.
Problem reported by Luca Borzacchiello (Bug#43040).
* bootstrap.conf (gnulib_modules): Add hash.
* src/grep.c: Include stdint.h, for SIZE_WIDTH.
Include hash.h.
(struct patloc, patloc, patlocs_allocated, patlocs_used):
Rename from struct FL_pair, fl_pair, n_fl_pair_slots, n_pattern_files,
respectively, since the data type is no longer a pair.
All uses changed.
(struct patloc): New member FILELINE.  The lineno member is now
ptrdiff_t since nowadays we prefer signed types.
(pattern_array, patterns_table): New static vars.
(count_nl_bytes, fl_add): Remove; no longer used.
(hash_pattern, compare_patterns, update_patterns): New functions.
update_patterns does what fl_add used to do, plus remove dups.
(pattern_file_name): Adjust to change from fl_pair to patloc.
(main): Move some variables to inner blocks for clarity.
Maintain the pattern_table hash of all patterns.
Update pattern_array to match keys, and use update_patterns
instead of fl_add to remove duplicate keys.
* tests/filename-lineno.pl (invalid-re-2-files)
(invalid-re-2-files2, invalid-re-2e): Ensure regexps are unique in
tests so that dups aren’t removed in diagnostics.
(invalid-re-line-numbers): New test.

1 files changed, 1 insertions, 0 deletions

diff --git a/bootstrap.conf b/bootstrap.conf
index ef142fcd..fceb3188 100644
--- a/bootstrap.conf
+++ b/bootstrap.conf
@@ -49,6 +49,7 @@ git-version-gen
 gitlog-to-changelog
 gnu-web-doc-update
 gnupload
+hash
 ignore-value
 intprops
 inttypes