Implement PCRE2_EXTRA_CASELESS_RESTRICT and related features

ChangeLog

@@ -36,6 +36,13 @@ configure.ac and CMakeLists.txt.
 8. Fixed a bug in pcre2test when a ridiculously large string repeat required a 
 stupid amount of memory. It now gives a clean realloc() failure error.
 
+9. Updates to restrict the interaction between ASCII and non-ASCII characters
+for caseless matching and items like \d:
+
+   (a) Added PCRE2_EXTRA_CASELESS_RESTRICT to lock out mixing of ASCII and 
+       non-ASCII when matching caselessly. This is also /r in pcre2test and 
+       (?r) within patterns.
+
 
 Version 10.42 11-December-2022
 ------------------------------

HACKING

@@ -1,4 +1,4 @@
-Technical Notes about PCRE2
+Technical notes about PCRE2
 ---------------------------
 
 These are very rough technical notes that record potentially useful information
@@ -248,7 +248,6 @@ by a length and an offset into the pattern to specify the name.
 The following have one data item that follows in the next vector element:
 
 META_BIGVALUE         Next is a literal >= META_END
-META_OPTIONS          (?i) and friends (data is new option bits)
 META_POSIX            POSIX class item (data identifies the class)
 META_POSIX_NEG        negative POSIX class item (ditto)
 
@@ -298,6 +297,11 @@ META_MINMAX           {n,m}  repeat
 META_MINMAX_PLUS      {n,m}+ repeat
 META_MINMAX_QUERY     {n,m}? repeat
 
+This one is followed by two elements, giving the new option settings for the 
+main and extra options, respectively.
+
+META_OPTIONS          (?i) and friends
+
 This one is followed by three elements. The first is 0 for '>' and 1 for '>=';
 the next two are the major and minor numbers:
 
@@ -827,4 +831,4 @@ not a real opcode, but is used to check at compile time that tables indexed by
 opcode are the correct length, in order to catch updating errors.
 
 Philip Hazel
-April 2022
+January 2023

maint/GenerateUcd.py

@@ -109,6 +109,8 @@
 # 10-January-2022:   Addition of general Boolean property support
 # 12-January-2022:   Merge scriptx and bidiclass fields
 # 14-January-2022:   Enlarge Boolean property offset to 12 bits
+# 28-January-2023:   Remove ASCII "other case" from non-ASCII character that
+#                      are present in caseless sets.
 #
 # ----------------------------------------------------------------------------
 #
@@ -710,6 +712,16 @@ def write_bitsets(list, item_size):
 
 # End of block of code for creating offsets for caseless matching sets.
 
+# Scan the caseless sets, and for any non-ASCII character that has an ASCII
+# character as its "base" other case, remove the other case. This makes it
+# easier to handle those characters when the PCRE2 option for not mixing ASCII
+# and non-ASCII is enabled. In principle one should perhaps scan for a 
+# non-ASCII alternative, but in practice these don't exist.
+
+for s in caseless_sets:
+  for x in s:
+    if x > 127 and x + other_case[x] < 128:
+      other_case[x] = 0  
 
 # Combine all the tables
 

maint/ucptest.c

@@ -471,7 +471,7 @@ switch(bidi)
 printf("U+%04X %s %s: %s, %s, %s", c, bidiclass, typename, fulltypename,
   scriptname, graphbreak);
 
-if (is_just_one && othercase != c)
+if (is_just_one && (othercase != c || caseset != 0))
   {
   printf(", U+%04X", othercase);
   if (caseset != 0)

src/pcre2.h.in

@@ -5,7 +5,7 @@
 /* This is the public header file for the PCRE library, second API, to be
 #included by applications that call PCRE2 functions.
 
-           Copyright (c) 2016-2021 University of Cambridge
+           Copyright (c) 2016-2023 University of Cambridge
 
 -----------------------------------------------------------------------------
 Redistribution and use in source and binary forms, with or without
@@ -153,6 +153,7 @@ D   is inspected during pcre2_dfa_match() execution
 #define PCRE2_EXTRA_ESCAPED_CR_IS_LF         0x00000010u  /* C */
 #define PCRE2_EXTRA_ALT_BSUX                 0x00000020u  /* C */
 #define PCRE2_EXTRA_ALLOW_LOOKAROUND_BSK     0x00000040u  /* C */
+#define PCRE2_EXTRA_CASELESS_RESTRICT        0x00000080u  /* C */
 
 /* These are for pcre2_jit_compile(). */