Update upstream source from tag 'upstream/1.0'

Update to upstream version '1.0'
with Debian dir 4875e7dc9f7277205f0086a63ee21ccdb1d54593

1 files changed, 34 insertions, 20 deletions

diff --git a/lib/wcwidth.c b/lib/wcwidth.c
index 1e5e87c..f99a0a6 100644
--- a/lib/wcwidth.c
+++ b/lib/wcwidth.c
@@ -1,26 +1,17 @@
 /* Determine the number of screen columns needed for a character.
-   Copyright (C) 2006-2007, 2010-2018 Free Software Foundation, Inc.
+   Copyright (C) 2006-2007, 2010-2022 Free Software Foundation, Inc.
 
-   This program is free software: you can redistribute it and/or
-   modify it under the terms of either:
+   This file 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 version 2.1 of the
+   License, or (at your option) any later version.
 
-     * the GNU Lesser General Public License as published by the Free
-       Software Foundation; either version 3 of the License, or (at your
-       option) any later version.
-
-   or
-
-     * the GNU General Public License as published by the Free
-       Software Foundation; either version 2 of the License, or (at your
-       option) any later version.
-
-   or both in parallel, as here.
-   This program is distributed in the hope that it will be useful,
+   This file is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
+   GNU Lesser General Public License for more details.
 
-   You should have received a copy of the GNU General Public License
+   You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
 
 #include <config.h>
@@ -35,17 +26,40 @@
 #include "streq.h"
 #include "uniwidth.h"
 
+/* Returns 1 if the current locale is an UTF-8 locale, 0 otherwise.  */
+static inline int
+is_locale_utf8 (void)
+{
+  const char *encoding = locale_charset ();
+  return STREQ_OPT (encoding, "UTF-8", 'U', 'T', 'F', '-', '8', 0, 0, 0, 0);
+}
+
+#if GNULIB_WCHAR_SINGLE_LOCALE
+/* When we know that the locale does not change, provide a speedup by
+   caching the value of is_locale_utf8.  */
+static int cached_is_locale_utf8 = -1;
+static inline int
+is_locale_utf8_cached (void)
+{
+  if (cached_is_locale_utf8 < 0)
+    cached_is_locale_utf8 = is_locale_utf8 ();
+  return cached_is_locale_utf8;
+}
+#else
+/* By default, don't make assumptions, hence no caching.  */
+# define is_locale_utf8_cached is_locale_utf8
+#endif
+
 int
 wcwidth (wchar_t wc)
 #undef wcwidth
 {
   /* In UTF-8 locales, use a Unicode aware width function.  */
-  const char *encoding = locale_charset ();
-  if (STREQ_OPT (encoding, "UTF-8", 'U', 'T', 'F', '-', '8', 0, 0, 0 ,0))
+  if (is_locale_utf8_cached ())
     {
       /* We assume that in a UTF-8 locale, a wide character is the same as a
          Unicode character.  */
-      return uc_width (wc, encoding);
+      return uc_width (wc, "UTF-8");
     }
   else
     {