Fix regexp character class syntax property ghost matching bug

The syntax-table-dependent regexp character classes [:space:],
[:word:] and [:punct:] always use the buffer-local syntax table for
performance reasons.  Fix a bug that could cause ghost (mis)matches
from use of lingering state by constructs that do use syntax
properties, such as `\sX`.

* src/regex-emacs.c (BUFFER_SYNTAX): New macro.
(ISPUNCT, ISSPACE, ISWORD): Use BUFFER_SYNTAX instead of SYNTAX.
(regex_compile): Delete syntax table setup code that is no longer
needed.
* test/src/regex-emacs-tests.el (regex-emacs-syntax-properties):
New regression test.

1 files changed, 12 insertions, 12 deletions

diff --git a/src/regex-emacs.c b/src/regex-emacs.c
index 51fc2b0558d..7e75f0ac597 100644
--- a/src/regex-emacs.c
+++ b/src/regex-emacs.c
@@ -47,6 +47,9 @@
 /* Make syntax table lookup grant data in gl_state.  */
 #define SYNTAX(c) syntax_property (c, 1)
 
+/* Explicit syntax lookup using the buffer-local table.  */
+#define BUFFER_SYNTAX(c) syntax_property (c, 0)
+
 #define RE_MULTIBYTE_P(bufp) ((bufp)->multibyte)
 #define RE_TARGET_MULTIBYTE_P(bufp) ((bufp)->target_multibyte)
 #define RE_STRING_CHAR(p, multibyte) \
@@ -132,18 +135,22 @@
 
 #define ISLOWER(c) lowercasep (c)
 
+#define ISUPPER(c) uppercasep (c)
+
+/* The following predicates use the buffer-local syntax table and
+   ignore syntax properties, for consistency with the up-front
+   assumptions made at compile time.  */
+
 #define ISPUNCT(c) (IS_REAL_ASCII (c)                           \
                     ? ((c) > ' ' && (c) < 0177                  \
                        && !(((c) >= 'a' && (c) <= 'z')          \
                             || ((c) >= 'A' && (c) <= 'Z')       \
                             || ((c) >= '0' && (c) <= '9')))     \
-                    : SYNTAX (c) != Sword)
+                    : BUFFER_SYNTAX (c) != Sword)
 
-#define ISSPACE(c) (SYNTAX (c) == Swhitespace)
+#define ISSPACE(c) (BUFFER_SYNTAX (c) == Swhitespace)
 
-#define ISUPPER(c) uppercasep (c)
-
-#define ISWORD(c) (SYNTAX (c) == Sword)
+#define ISWORD(c) (BUFFER_SYNTAX (c) == Sword)
 
 /* Use alloca instead of malloc.  This is because using malloc in
    re_search* or re_match* could cause memory leaks when C-g is used
@@ -2048,13 +2055,6 @@ regex_compile (re_char *pattern, ptrdiff_t size,
                        is_xdigit, since they can only match ASCII characters.
                        We don't need to handle them for multibyte.  */
 
-                    /* Setup the gl_state object to its buffer-defined value.
-                       This hardcodes the buffer-global syntax-table for ASCII
-                       chars, while the other chars will obey syntax-table
-                       properties.  It's not ideal, but it's the way it's been
-                       done until now.  */
-                    SETUP_BUFFER_SYNTAX_TABLE ();
-
                     for (c = 0; c < 0x80; ++c)
                       if (re_iswctype (c, cc))
                         {