Make a missing right brace on \N{ fatal

It was decided that this should be a fatal error instead of a warning.

Also some comments were updated..

diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 486a515..4a12889 100644 (file)
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -2512,32 +2512,32 @@ can vary from one line to the next.
 
 (F) Missing right brace in C<\x{...}>, C<\p{...}>, C<\P{...}>, or C<\N{...}>.
 
-=item Missing right brace on \\N{} or unescaped left brace after \\N.  Assuming the latter
+=item Missing right brace on \\N{} or unescaped left brace after \\N
 
-(W syntax)
-C<\N> has traditionally been followed by a name enclosed in braces,
-meaning the character (or sequence of characters) given by that name.
+(F)
+C<\N> has two meanings.
+
+The traditional one has it followed by a name enclosed
+in braces, meaning the character (or sequence of characters) given by that name.
 Thus C<\N{ASTERISK}> is another way of writing C<*>, valid in both
-double-quoted strings and regular expression patterns.
-In patterns, it doesn't have the meaning an unescaped C<*> does.
+double-quoted strings and regular expression patterns.  In patterns, it doesn't
+have the meaning an unescaped C<*> does.
 
-Starting in Perl 5.12.0, C<\N> also can have an additional meaning in patterns,
-namely to match a non-newline character.  (This is like C<.> but is not
-affected by the C</s> modifier.)
+Starting in Perl 5.12.0, C<\N> also can have an additional meaning (only) in
+patterns, namely to match a non-newline character.  (This is like C<.> but is
+not affected by the C</s> modifier.)
 
 This can lead to some ambiguities.  When C<\N> is not followed immediately by a
 left brace, Perl assumes the "match non-newline character" meaning.  Also, if
 the braces form a valid quantifier such as C<\N{3}> or C<\N{5,}>, Perl assumes
 that this means to match the given quantity of non-newlines (in these examples,
-3, and 5 or more, respectively).  In all other case, where there is a C<\N{>
+3; and 5 or more, respectively).  In all other case, where there is a C<\N{>
 and a matching C<}>, Perl assumes that a character name is desired.
 
 However, if there is no matching C<}>, Perl doesn't know if it was mistakenly
-omitted, or if "match non-newline" followed by "match a C<{>" was desired.
-It assumes the latter because that is actually a valid interpretation as
-written, unlike the other case.  If you meant the former, you need to add the
-matching right brace.  If you did mean the latter, you can silence this warning
-by writing instead C<\N\{>.
+omitted, or if "match non-newline" followed by "match a C<{>" was desired, and
+raises this error.  If you meant the former, add the right brace; if you meant
+the latter, escape the brace with a backslash, like so: C<\N\{>
 
 =item Missing right curly or square bracket
 

diff --git a/toke.c b/toke.c
index fcfdd71..997b46a 100644 (file)
--- a/toke.c
+++ b/toke.c
@@ -2968,10 +2968,10 @@ S_scan_const(pTHX_ char *start)
                 * errors and upgrading to utf8) is:
                 *  Further disambiguate between the two meanings of \N, and if
                 *      not a charname, go process it elsewhere
-                *  If of form \N{U+...}, pass it through if a pattern; otherwise
-                *      convert to utf8
-                *  Otherwise must be \N{NAME}: convert to \N{U+c1.c2...} if a pattern;
-                *      otherwise convert to utf8 */
+                *  If of form \N{U+...}, pass it through if a pattern;
+                *      otherwise convert to utf8
+                *  Otherwise must be \N{NAME}: convert to \N{U+c1.c2...} if a
+                *  pattern; otherwise convert to utf8 */
 
                /* Here, s points to the 'N'; the test below is guaranteed to
                 * succeed if we are being called on a pattern as we already
@@ -2985,27 +2985,14 @@ S_scan_const(pTHX_ char *start)
                }
                s++;
 
-               /* If there is no matching '}', it is an error outside of a
-                * pattern, or ambiguous inside. */
+               /* If there is no matching '}', it is an error. */
                if (! (e = strchr(s, '}'))) {
                    if (! PL_lex_inpat) {
                        yyerror("Missing right brace on \\N{}");
-                       continue;
-                   }
-                   else {
-
-                       /* A missing brace means it can't be a legal character
-                        * name, and it could be a legal "match non-newline".
-                        * But it's kind of weird without an unescaped left
-                        * brace, so warn. */
-                       if (ckWARN(WARN_SYNTAX)) {
-                           Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
-                                   "Missing right brace on \\N{} or unescaped left brace after \\N.  Assuming the latter");
-                       }
-                       s -= 3; /* Backup over cur char, {, N, to the '\' */
-                       *d++ = NATIVE_TO_NEED(has_utf8,'\\');
-                       goto default_action;
+                   } else {
+                       yyerror("Missing right brace on \\N{} or unescaped left brace after \\N.");
                    }
+                   continue;
                }
 
                /* Here it looks like a named character */
@@ -3053,9 +3040,7 @@ S_scan_const(pTHX_ char *start)
 
                        /* Pass through to the regex compiler unchanged.  The
                         * reason we evaluated the number above is to make sure
-                        * there wasn't a syntax error.  It also makes sure
-                        * that the syntax created below, \N{Uc1.c2...}, is
-                        * internal-only */
+                        * there wasn't a syntax error. */
                        s -= 5;     /* Include the '\N{U+' */
                        Copy(s, d, e - s + 1, char);    /* 1 = include the } */
                        d += e - s + 1;