doc: Fix description of regexp/locale encoding interaction.

* doc/ref/api-regex.texi (Regexp Functions): Update paragraph that
  mentions locale encoding and strings-as-bytes.

* test-suite/tests/regexp.test ("nonascii locales")["match structures
  refer to char offsets, non-ASCII pattern"]: New test.

diff --git a/doc/ref/api-regex.texi b/doc/ref/api-regex.texi
index 11a31fc..082fb87 100644 (file)
--- a/doc/ref/api-regex.texi
+++ b/doc/ref/api-regex.texi
@@ -1,6 +1,6 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Guile Reference Manual.
-@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2007, 2009, 2010
+@c Copyright (C)  1996, 1997, 2000, 2001, 2002, 2003, 2004, 2007, 2009, 2010, 2012
 @c   Free Software Foundation, Inc.
 @c See the file guile.texi for copying conditions.
 
@@ -54,11 +54,12 @@ Zero bytes (@code{#\nul}) cannot be used in regex patterns or input
 strings, since the underlying C functions treat that as the end of
 string.  If there's a zero byte an error is thrown.
 
-Patterns and input strings are treated as being in the locale
-character set if @code{setlocale} has been called (@pxref{Locales}),
-and in a multibyte locale this includes treating multi-byte sequences
-as a single character.  (Guile strings are currently merely bytes,
-though this may change in the future, @xref{Conversion to/from C}.)
+Internally, patterns and input strings are converted to the current
+locale's encoding, and then passed to the C library's regular expression
+routines (@pxref{Regular Expressions,,, libc, The GNU C Library
+Reference Manual}).  The returned match structures always point to
+characters in the strings, not to individual bytes, even in the case of
+multi-byte encodings.
 
 @deffn {Scheme Procedure} string-match pattern str [start]
 Compile the string @var{pattern} into a regular expression and compare

diff --git a/test-suite/tests/regexp.test b/test-suite/tests/regexp.test
index 8217a41..ef59465 100644 (file)
--- a/test-suite/tests/regexp.test
+++ b/test-suite/tests/regexp.test
@@ -1,8 +1,9 @@
 ;;;; regexp.test ---  test Guile's regexps   -*- coding: utf-8; mode: scheme -*-
 ;;;; Jim Blandy <jimb@red-bean.com> --- September 1999
 ;;;;
-;;;;   Copyright (C) 1999, 2004, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
-;;;; 
+;;;;   Copyright (C) 1999, 2004, 2006, 2007, 2008, 2009, 2010,
+;;;;      2012 Free Software Foundation, Inc.
+;;;;
 ;;;; This library is free software; you can redistribute it and/or
 ;;;; modify it under the terms of the GNU Lesser General Public
 ;;;; License as published by the Free Software Foundation; either
@@ -280,4 +281,12 @@
     (with-locale "en_US.utf8"
       ;; bug #31650
       (equal? (match:substring (string-match ".*" "calçot") 0)
-              "calçot"))))
+              "calçot")))
+
+  (pass-if "match structures refer to char offsets, non-ASCII pattern"
+    (with-locale "en_US.utf8"
+      ;; bug #31650
+      (equal? (match:substring (string-match "λ: The Ultimate (.*)"
+                                             "λ: The Ultimate GOTO")
+                               1)
+              "GOTO"))))