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, 16 insertions, 3 deletions

diff --git a/tests/filename-lineno.pl b/tests/filename-lineno.pl
index 998af73d..8940b1c7 100755
--- a/tests/filename-lineno.pl
+++ b/tests/filename-lineno.pl
@@ -48,7 +48,7 @@ my @Tests =
    # Show that with two or more errors, grep now prints all diagnostics:
    ['invalid-re-2-files', '-f g -f h', {EXIT=>2},
     {AUX=>{g=>"1\n2[[\n3\n4[[\n"}},
-    {AUX=>{h=>"\n\n[[\n"}},
+    {AUX=>{h=>"5\n6\n7[[\n"}},
     $err_subst,
     {ERR => "$prog: g:2: Unmatched [...\n"
          . "$prog: g:4: Unmatched [...\n"
@@ -59,7 +59,7 @@ my @Tests =
    # Like the above, but on the other lines.
    ['invalid-re-2-files2', '-f g -f h', {EXIT=>2},
     {AUX=>{g=>"1[[\n2\n3[[\n4\n"}},
-    {AUX=>{h=>"[[\n[[\n\n"}},
+    {AUX=>{h=>"5[[\n6[[\n7\n"}},
     $err_subst,
     {ERR => "$prog: g:1: Unmatched [...\n"
          . "$prog: g:3: Unmatched [...\n"
@@ -68,9 +68,22 @@ my @Tests =
     },
    ],
 
+   # Make sure the line numbers are right when some regexps are duplicates.
+   ['invalid-re-line-numbers', '-f g -f h', {EXIT=>2},
+    {AUX=>{g=>"1[[\n\n3[[\n\n5[[\n"}},
+    {AUX=>{h=>"1[[\n\n\n4[[\n\n6[[\n"}},
+    $err_subst,
+    {ERR => "$prog: g:1: Unmatched [...\n"
+         . "$prog: g:3: Unmatched [...\n"
+         . "$prog: g:5: Unmatched [...\n"
+         . "$prog: h:4: Unmatched [...\n"
+         . "$prog: h:6: Unmatched [...\n"
+    },
+   ],
+
    # Show that with two '-e'-specified erroneous regexps,
    # there is no file name or line number.
-   ['invalid-re-2e', '-e "[[" -e "[["', {EXIT=>2},
+   ['invalid-re-2e', '-e "1[[" -e "2[["', {EXIT=>2},
     $err_subst,
     {ERR => "$prog: Unmatched [...\n" x 2},
    ],