* src/regex-emacs.c (analyze_first): Fix incorrect optimization

The optimization was incorrect in a particular corner case.
In this fix I just disable it conservatively for more cases because
it's not obvious how to fix it while preserving the "good" cases.

We may find a better fix by using an approach like the one
in `mutually_exhaustive_aux`, but for now this is good enough,
especially since \{..\} repetitions are not used very frequently.

* test/src/regex-resources/PTESTS: New test.

diff --git a/src/regex-emacs.c b/src/regex-emacs.c
index 338323cf79e5e5324bb8b2a43f59dd86dc235018..ae82dd63917e1056d0351ce349861e6771c7a8a2 100644 (file)
--- a/src/regex-emacs.c
+++ b/src/regex-emacs.c
@@ -3086,8 +3086,10 @@ analyze_first (re_char *p, re_char *pend, char *fastmap, bool multibyte)
          /* We only care about one iteration of the loop, so we don't
             need to consider the case where this behaves like an
             on_failure_jump.  */
-         continue;
-
+         /* FIXME: Sadly, the above is not true when the loop's body
+            can match the empty string :-(  */
+         /* continue; */
+         return -1;
 
        case set_number_at:
          p += 4;

diff --git a/test/src/regex-resources/PTESTS b/test/src/regex-resources/PTESTS
index 68acc314d377f2c43601adcadf28deb7139ea77c..59dd4b3bc212ff1cb3c8c07640cf971dbfa01f8c 100644 (file)
--- a/test/src/regex-resources/PTESTS
+++ b/test/src/regex-resources/PTESTS
@@ -269,6 +269,7 @@
 #W the expected result for \([a-c]*\)\{2,\} is failure which isn't correct
 1¦3¦\([a-c]*\)\{2,\}¦abcdefg¦
 1¦3¦\([a-c]*\)\{1,\}¦abcdefg¦
+0¦0¦\([a-c]*\)\{2,\}¦gabcdefg¦
 -1¦-1¦a\{64,\}¦aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa¦
 # GA142
 1¦3¦a\{2,3\}¦aaaa¦