Improve error offsets for character classes (PCRE2Project#548)

* Error offset should be advanced by one character for "[\d-z]"
  invalid range error

  The code does a 1-char lookahead for a hyphen, but then doesn't
  advance the pointer to consume the hyphen when returning the error.

  Perl's error message (with "use warnings") does advance to just
  after the hyphen, so PCRE2 should match.

  Fixes PCRE2Project#545.

* Also improve error offsets for [[:bad:]], [[=...=]] and [z-\p{...}]
  cases

Author: NWilson

src/pcre2_compile.c

@@ -3702,6 +3702,7 @@ while (ptr < ptrend)
 
         if (class_range_state == RANGE_STARTED)
           {
+          ptr = tempptr + 2;
           errorcode = ERR50;
           goto FAILED;
           }
@@ -3723,8 +3724,9 @@ while (ptr < ptrend)
 
         if (*ptr != CHAR_COLON)
           {
+          ptr = tempptr + 2;
           errorcode = ERR13;
-          goto FAILED_BACK;
+          goto FAILED;
           }
 
         if (*(++ptr) == CHAR_CIRCUMFLEX_ACCENT)
@@ -3734,19 +3736,18 @@ while (ptr < ptrend)
           }
 
         posix_class = check_posix_name(ptr, (int)(tempptr - ptr));
+        ptr = tempptr + 2;
         if (posix_class < 0)
           {
           errorcode = ERR30;
           goto FAILED;
           }
-        ptr = tempptr + 2;
 
         /* Set "a hyphen is forbidden to be the start of a range". For the '-]'
         case, the hyphen is treated as a literal, but for '-1' it is disallowed
         (because it would be interpreted as range). */
 
         class_range_state = RANGE_FORBID_NO;
-        class_range_forbid_ptr = ptr;
         class_op_state = CLASS_OP_OPERAND;
 
         /* When PCRE2_UCP is set, unless PCRE2_EXTRA_ASCII_POSIX is set, some
@@ -3989,6 +3990,7 @@ while (ptr < ptrend)
         {
         *parsed_pattern++ = CHAR_MINUS;
         class_range_state = RANGE_FORBID_STARTED;
+        class_range_forbid_ptr = ptr;
         }
 
       /* Handle a literal character */
@@ -4073,40 +4075,8 @@ while (ptr < ptrend)
           errorcode = ERR7;
           ptr--;
           goto FAILED;
-          }
-
-        /* The second part of a range can be a single-character escape
-        sequence (detected above), but not any of the other escapes. Perl
-        treats a hyphen as a literal in such circumstances. However, in Perl's
-        warning mode, a warning is given, so PCRE now faults it, as it is
-        almost certainly a mistake on the user's part. */
 
-        if (class_range_state == RANGE_STARTED)
-          {
-          errorcode = ERR50;
-          goto FAILED;
-          }
-
-        /* Perl gives a warning unless the hyphen following a multi-character
-        escape is the last character in the class. PCRE throws an error. */
-
-        if (class_range_state == RANGE_FORBID_STARTED)
-          {
-          ptr = class_range_forbid_ptr;
-          errorcode = ERR50;
-          goto FAILED;
-          }
-
-        /* Of the remaining escapes, only those that define characters are
-        allowed in a class. None may start a range. */
-
-        class_range_state = RANGE_FORBID_NO;
-        class_range_forbid_ptr = ptr;
-        class_op_state = CLASS_OP_OPERAND;
-
-        switch(escape)
-          {
-          case ESC_N:
+          case ESC_N:     /* Not permitted by Perl either */
           errorcode = ERR71;
           goto FAILED;
 
@@ -4143,7 +4113,6 @@ while (ptr < ptrend)
             if (negated) escape = (escape == ESC_P)? ESC_p : ESC_P;
             *parsed_pattern++ = META_ESCAPE + escape;
             *parsed_pattern++ = (ptype << 16) | pdata;
-            class_range_forbid_ptr = ptr;
             }
 #else
           errorcode = ERR45;
@@ -4156,6 +4125,34 @@ while (ptr < ptrend)
           ptr--;
           goto FAILED;
           }
+
+        /* All the switch-cases above which end in "break" describe a set
+        of characters. None may start a range. */
+
+        /* The second part of a range can be a single-character escape
+        sequence (detected above), but not any of the other escapes. Perl
+        treats a hyphen as a literal in such circumstances. However, in Perl's
+        warning mode, a warning is given, so PCRE now faults it, as it is
+        almost certainly a mistake on the user's part. */
+
+        if (class_range_state == RANGE_STARTED)
+          {
+          errorcode = ERR50;
+          goto FAILED;
+          }
+
+        /* Perl gives a warning unless the hyphen following a multi-character
+        escape is the last character in the class. PCRE throws an error. */
+
+        if (class_range_state == RANGE_FORBID_STARTED)
+          {
+          ptr = class_range_forbid_ptr;
+          errorcode = ERR50;
+          goto FAILED;
+          }
+
+        class_range_state = RANGE_FORBID_NO;
+        class_op_state = CLASS_OP_OPERAND;
         }
 
       /* Proceed to next thing in the class. */

testdata/testinput2

@@ -7008,4 +7008,12 @@ a)"xI
 
 /[[:digit:]\Q\E-H]+/
 
+/[z-[:space:]]/
+
+/[z-\d]/
+
+/[[:space:]-z]/
+
+/[\d-z]/
+
 # End of testinput2

testdata/testinput5

@@ -3189,4 +3189,12 @@
 /^([\h\x{9000}\x{9002}\x{9004}][\v\x{9000}\x{9002}\x{9004}\x{9006}\x{9008}][\h\v\x{9000}],){4}$/B,utf
   \x09\x0a\x0d,\x{1680}\x{2028}\x{1680},\x{180e}\x{2029}\x{180e},\x{9000}\x{9000}\x{9000},
 
+/[z-\p{Lu}]/
+
+/[z-\pL]/
+
+/[\p{Lu}-z]/
+
+/[\pL-z]/
+
 # End of testinput5

testdata/testoutput2

@@ -2170,13 +2170,13 @@ Starting code units: % 0 1 A B C D E F G H I J K L M N O P Q R S T U V W
 Subject length lower bound = 1
 
 /[[.ch.]]/I
-Failed: error 113 at offset 1: POSIX collating elements are not supported
+Failed: error 113 at offset 7: POSIX collating elements are not supported
 
 /[[=ch=]]/I
-Failed: error 113 at offset 1: POSIX collating elements are not supported
+Failed: error 113 at offset 7: POSIX collating elements are not supported
 
 /[[:rhubarb:]]/I
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 12: unknown POSIX class name
 
 /[[:upper:]]/Ii
 Capture group count = 0
@@ -8775,31 +8775,31 @@ Failed: error 162 at offset 4: subpattern name expected
 Failed: error 162 at offset 4: subpattern name expected
 
 /[[:foo:]]/
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 8: unknown POSIX class name
 
 /[[:1234:]]/
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 9: unknown POSIX class name
 
 /[[:f\oo:]]/
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 9: unknown POSIX class name
 
 /[[: :]]/
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 6: unknown POSIX class name
 
 /[[:...:]]/
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 8: unknown POSIX class name
 
 /[[:l\ower:]]/
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 11: unknown POSIX class name
 
 /[[:abc\:]]/
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 9: unknown POSIX class name
 
 /[abc[:x\]pqr:]]/
-Failed: error 130 at offset 6: unknown POSIX class name
+Failed: error 130 at offset 14: unknown POSIX class name
 
 /[[:a\dz:]]/
-Failed: error 130 at offset 3: unknown POSIX class name
+Failed: error 130 at offset 9: unknown POSIX class name
 
 /(^(a|b\g<-1'c))/
 Failed: error 157 at offset 8: \g is not followed by a braced, angle-bracketed, or quoted name/number or by a plain number
@@ -11524,7 +11524,7 @@ Failed: error 171 at offset 4: \N is not supported in a class
     aNc
 
 /a[B-\Nc]/
-Failed: error 150 at offset 6: invalid range in character class
+Failed: error 171 at offset 6: \N is not supported in a class
 
 /a[B\Nc]/
 Failed: error 171 at offset 5: \N is not supported in a class
@@ -13347,16 +13347,16 @@ Failed: error 178 at offset 5: digits missing after \x or in \x{} or \o{} or \N{
 ------------------------------------------------------------------
 
 /[a-[:digit:]]+/
-Failed: error 150 at offset 4: invalid range in character class
+Failed: error 150 at offset 12: invalid range in character class
 
 /[A-[:digit:]]+/
-Failed: error 150 at offset 4: invalid range in character class
+Failed: error 150 at offset 12: invalid range in character class
 
 /[a-[.xxx.]]+/
-Failed: error 150 at offset 4: invalid range in character class
+Failed: error 150 at offset 10: invalid range in character class
 
 /[a-[=xxx=]]+/
-Failed: error 150 at offset 4: invalid range in character class
+Failed: error 150 at offset 10: invalid range in character class
 
 /[a-[!xxx!]]+/
 Failed: error 108 at offset 3: range out of order in character class
@@ -13477,7 +13477,7 @@ No match
 No match
 
 /[a[:<:]] should give error/
-Failed: error 130 at offset 4: unknown POSIX class name
+Failed: error 130 at offset 7: unknown POSIX class name
 
 /(?=ab\K)/aftertext,allow_lookaround_bsk
     abcd\=startchar
@@ -15879,11 +15879,11 @@ Failed: error 125 at offset 13: length of lookbehind assertion is not limited
 # Perl accepts these, but gives a warning. We can't warn, so give an error.
 
 /[a-[:digit:]]+/
-Failed: error 150 at offset 4: invalid range in character class
+Failed: error 150 at offset 12: invalid range in character class
     a-a9-a
 
 /[A-[:digit:]]+/
-Failed: error 150 at offset 4: invalid range in character class
+Failed: error 150 at offset 12: invalid range in character class
     A-A9-A
 
 /[a-\d]+/
@@ -16020,7 +16020,7 @@ Failed: error 128 at offset 63: atomic assertion expected after (?( or (?(?C)
     .+(?(?C'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'))?!XXXX.=X
 
 /[:[:alnum:]-[[a:lnum:]+/
-Failed: error 150 at offset 11: invalid range in character class
+Failed: error 150 at offset 12: invalid range in character class
 
 /((?(?C'')\QX\E(?!((?(?C'')(?!X=X));=)r*X=X));=)/
 Failed: error 128 at offset 11: atomic assertion expected after (?( or (?(?C)
@@ -16654,10 +16654,10 @@ Subject length lower bound = 3
 ------------------------------------------------------------------
 
 /[Q-\N]/B,bad_escape_is_literal
-Failed: error 150 at offset 5: invalid range in character class
+Failed: error 171 at offset 5: \N is not supported in a class
 
 /[\s-_]/bad_escape_is_literal
-Failed: error 150 at offset 3: invalid range in character class
+Failed: error 150 at offset 4: invalid range in character class
 
 /[_-\s]/bad_escape_is_literal
 Failed: error 150 at offset 5: invalid range in character class
@@ -16857,19 +16857,19 @@ No match
 No match
 
 /[[:digit:]-a]/
-Failed: error 150 at offset 10: invalid range in character class
+Failed: error 150 at offset 11: invalid range in character class
 
 /[[:digit:]-[:print:]]/
-Failed: error 150 at offset 10: invalid range in character class
+Failed: error 150 at offset 11: invalid range in character class
 
 /[\d-a]/
-Failed: error 150 at offset 3: invalid range in character class
+Failed: error 150 at offset 4: invalid range in character class
 
 /[\H-z]/
-Failed: error 150 at offset 3: invalid range in character class
+Failed: error 150 at offset 4: invalid range in character class
 
 /[\d-[:print:]]/
-Failed: error 150 at offset 3: invalid range in character class
+Failed: error 150 at offset 4: invalid range in character class
 
 # Perl gets the second of these wrong, giving no match.
 
@@ -20619,7 +20619,7 @@ Failed: error 211 at offset 7: brackets needed to clarify operator precedence in
 No match
 
 /[\d-z]/B,alt_extended_class
-Failed: error 150 at offset 3: invalid range in character class
+Failed: error 150 at offset 4: invalid range in character class
 
 /[z-\d]/B,alt_extended_class
 Failed: error 150 at offset 5: invalid range in character class
@@ -20654,16 +20654,28 @@ Failed: error 207 at offset 118: character classes are too deeply nested
 # --------------
 
 /[[:digit:]   -Z]/xx
-Failed: error 150 at offset 10: invalid range in character class
+Failed: error 150 at offset 14: invalid range in character class
 
 /[\d   -Z]/xx
-Failed: error 150 at offset 3: invalid range in character class
+Failed: error 150 at offset 7: invalid range in character class
 
 /[[:digit:]\E-H]/
-Failed: error 150 at offset 10: invalid range in character class
+Failed: error 150 at offset 13: invalid range in character class
 
 /[[:digit:]\Q\E-H]+/
-Failed: error 150 at offset 10: invalid range in character class
+Failed: error 150 at offset 15: invalid range in character class
+
+/[z-[:space:]]/
+Failed: error 150 at offset 12: invalid range in character class
+
+/[z-\d]/
+Failed: error 150 at offset 5: invalid range in character class
+
+/[[:space:]-z]/
+Failed: error 150 at offset 11: invalid range in character class
+
+/[\d-z]/
+Failed: error 150 at offset 4: invalid range in character class
 
 # End of testinput2
 Error -70: PCRE2_ERROR_BADDATA (unknown error number)