[COMMIT] Make Lisp reader errors more informative with over-long hex, octal characters

After some discussion with kevinfish in IRC, IMO the below will make things easier for people to follow what exactly the relevant error messages mean. APPROVE COMMIT NOTE: This patch has been committed. # HG changeset patch # User Aidan Kehoe <kehoea(a)parhasard.net&gt; # Date 1282413764 -3600 # Node ID 02d875ebd1ea4da4214e733f9a459dd508ddfc9d # Parent 04811a268716dbb77524e2ab2364a243a1c5c29c Make Lisp reader errors more informative with over-long hex, octal characters src/ChangeLog addition: 2010-08-21 Aidan Kehoe <kehoea(a)parhasard.net&gt; * lread.c (read_escape): Make error messages better reflect the text that was encountered, when overlong hex character escapes or non-Latin-1 octal character escapes are encountered. man/ChangeLog addition: 2010-08-21 Aidan Kehoe <kehoea(a)parhasard.net&gt; * lispref/objects.texi (Character Type): Go into more detail here on the specific type of error provoked on overlong hex character escapes and non-Latin-1 octal character escapes; give details of why the latter may be encountered, and what to do with such code. diff -r 04811a268716 -r 02d875ebd1ea man/ChangeLog --- a/man/ChangeLog Sun Aug 15 15:42:45 2010 +0100 +++ b/man/ChangeLog Sat Aug 21 19:02:44 2010 +0100 ＠＠ -1,3 +1,11 ＠＠ +2010-08-21 Aidan Kehoe <kehoea(a)parhasard.net&gt; + + * lispref/objects.texi (Character Type): + Go into more detail here on the specific type of error provoked on + overlong hex character escapes and non-Latin-1 octal character + escapes; give details of why the latter may be encountered, and + what to do with such code. + 2010-06-13 Stephen J. Turnbull <stephen(a)xemacs.org&gt; * external-widget.texi: Correct FSF address in permission notice. diff -r 04811a268716 -r 02d875ebd1ea man/lispref/objects.texi --- a/man/lispref/objects.texi Sun Aug 15 15:42:45 2010 +0100 +++ b/man/lispref/objects.texi Sat Aug 21 19:02:44 2010 +0100 ＠＠ -623,6 +623,8 ＠＠ ＠cindex backslash in character constant ＠cindex octal character code ＠cindex hexadecimal character code +＠cindex Overlong hex character escape +＠cindex Non-ISO-8859-1 octal character escape Finally, there are two read syntaxes involving character codes. It is not possible to represent multibyte or wide characters in this ＠＠ -643,14 +645,21 ＠＠ ＠samp{?\001} for the character ＠kbd{C-a}, and ＠code{?\002} for the character ＠kbd{C-b}. The reader will finalize the character and start reading the next token when a non-octal-digit is encountered or three -octal digits are read. +octal digits are read. When a given character code is above +＠code{#o377}, the Lisp reader signals an ＠code{invalid-read-syntax} +error. Such errors are typically provoked by code written for older +versions of GNU Emacs, where the absence of the #o octal syntax for +integers made the character syntax convenient for non-character +values. Those older versions of GNU Emacs are long obsolete, so +changing the code to use the #o integer escape is the best +solution. ＠pxref{Numbers}. The second consists of a question mark followed by a backslash, the character ＠samp{x}, and the character code in hexadecimal (up to two hexadecimal digits); thus, ＠samp{?\x41} for the character ＠kbd{A}, ＠samp{?\x1} for the character ＠kbd{C-a}, and ＠code{?\x2} for the character ＠kbd{C-b}. If more than two hexadecimal codes are given, the -reader signals an error. +reader signals an ＠code{invalid-read-syntax} error. ＠example ＠group diff -r 04811a268716 -r 02d875ebd1ea src/ChangeLog --- a/src/ChangeLog Sun Aug 15 15:42:45 2010 +0100 +++ b/src/ChangeLog Sat Aug 21 19:02:44 2010 +0100 ＠＠ -1,3 +1,10 ＠＠ +2010-08-21 Aidan Kehoe <kehoea(a)parhasard.net&gt; + + * lread.c (read_escape): + Make error messages better reflect the text that was encountered, + when overlong hex character escapes or non-Latin-1 octal character + escapes are encountered. + 2010-08-15 Aidan Kehoe <kehoea(a)parhasard.net&gt; * print.c (print_symbol): diff -r 04811a268716 -r 02d875ebd1ea src/lread.c --- a/src/lread.c Sun Aug 15 15:42:45 2010 +0100 +++ b/src/lread.c Sat Aug 21 19:02:44 2010 +0100 ＠＠ -1818,8 +1818,12 ＠＠ } } if (i >= 0400) - syntax_error ("Non-ISO-8859-1 character specified with octal escape", - make_int (i)); + { + read_syntax_error ((Ascbyte *) emacs_sprintf_malloc + (NULL, + "Non-ISO-8859-1 octal character escape, " + "?\\%.3o", i)); + } return i; } ＠＠ -1827,13 +1831,23 ＠＠ /* A hex escape, as in ANSI C, except that we only allow latin-1 characters to be read this way. What is "\x4e03" supposed to mean, anyways, if the internal representation is hidden? - This is also consistent with the treatment of octal escapes. */ + This is also consistent with the treatment of octal escapes. + + Note that we don't accept ?\XAB as specifying the character with + numeric value 171; it must be ?\xAB. */ { +#define OVERLONG_INFO "Overlong hex character escape, ?\\x" + REGISTER Ichar i = 0; REGISTER int count = 0; + Ascbyte seen[] = OVERLONG_INFO "\0\0\0\0\0"; + REGISTER Ascbyte *seenp = seen + sizeof (OVERLONG_INFO) - 1; + +#undef OVERLONG_INFO + while (++count <= 2) { - c = readchar (readcharfun); + c = readchar (readcharfun), *seenp = c, ++seenp; /* Remember, can't use isdigit(), isalpha() etc. on Ichars */ if (c >= '0' && c <= '9') i = (i << 4) + (c - '0'); else if (c >= 'a' && c <= 'f') i = (i << 4) + (c - 'a') + 10; ＠＠ -1847,21 +1861,12 ＠＠ if (count == 3) { - c = readchar (readcharfun); + c = readchar (readcharfun), *seenp = c, ++seenp; if ((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) { - Lisp_Object args[2]; - - if (c >= '0' && c <= '9') i = (i << 4) + (c - '0'); - else if (c >= 'a' && c <= 'f') i = (i << 4) + (c - 'a') + 10; - else if (c >= 'A' && c <= 'F') i = (i << 4) + (c - 'A') + 10; - - args[0] = build_ascstring ("?\\x%x"); - args[1] = make_int (i); - syntax_error ("Overlong hex character escape", - Fformat (2, args)); + read_syntax_error (seen); } unreadchar (readcharfun, c); } -- “Apart from the nine-banded armadillo, man is the only natural host of Mycobacterium leprae, although it can be grown in the footpads of mice.” -- Kumar & Clark, Clinical Medicine, summarising improbable leprosy research _______________________________________________ XEmacs-Patches mailing list XEmacs-Patches(a)xemacs.org http://calypso.tux.org/mailman/listinfo/xemacs-patches