Curved quotes in --batch diagnostics in non-UTF-8

When run with --batch, check that curved quotes are compatible with
the system locale before outputting them in diagnostics.
Problem reported by Eli Zaretskii in:
http://lists.gnu.org/archive/html/emacs-devel/2015-08/msg00594.html
* lisp/startup.el (command-line): Set internal--text-quoting-flag
after the standard display table is initialized.
* src/doc.c (default_to_grave_quoting_style): New function.
(text_quoting_style): Use it.
(text_quoting_flag): New static var, visible to Lisp as
internal--text-quoting-flag.
* src/emacs.c: Include <wchar.h> if available.
(using_utf8): New function.
(main): Use it to initialize text_quoting_flag.
* src/regex.h (btowc) [WIDE_CHAR_SUPPORT && emacs]:
Don't define, as it's not needed and it clashes with wchar.h.

1 files changed, 22 insertions, 11 deletions

diff --git a/src/doc.c b/src/doc.c
index 977953d53e5..9c9bdf3997a 100644
--- a/src/doc.c
+++ b/src/doc.c
@@ -688,24 +688,31 @@ the same file name is found in the `doc-directory'.  */)
 static unsigned char const LSQM[] = { uLSQM0, uLSQM1, uLSQM2 };
 static unsigned char const RSQM[] = { uRSQM0, uRSQM1, uRSQM2 };
 
+static bool
+default_to_grave_quoting_style (void)
+{
+  if (!text_quoting_flag)
+    return true;
+  if (! DISP_TABLE_P (Vstandard_display_table))
+    return false;
+  Lisp_Object dv = DISP_CHAR_VECTOR (XCHAR_TABLE (Vstandard_display_table),
+                                     LEFT_SINGLE_QUOTATION_MARK);
+  return (VECTORP (dv) && ASIZE (dv) == 1
+          && EQ (AREF (dv, 0), make_number ('`')));
+}
+
 /* Return the current effective text quoting style.  */
 enum text_quoting_style
 text_quoting_style (void)
 {
-  if (EQ (Vtext_quoting_style, Qgrave))
+  if (NILP (Vtext_quoting_style)
+      ? default_to_grave_quoting_style ()
+      : EQ (Vtext_quoting_style, Qgrave))
     return GRAVE_QUOTING_STYLE;
   else if (EQ (Vtext_quoting_style, Qstraight))
     return STRAIGHT_QUOTING_STYLE;
-  else if (NILP (Vtext_quoting_style)
-           && DISP_TABLE_P (Vstandard_display_table))
-    {
-      Lisp_Object dv = DISP_CHAR_VECTOR (XCHAR_TABLE (Vstandard_display_table),
-                                         LEFT_SINGLE_QUOTATION_MARK);
-      if (VECTORP (dv) && ASIZE (dv) == 1
-          && EQ (AREF (dv, 0), make_number ('`')))
-        return GRAVE_QUOTING_STYLE;
-    }
-  return CURVE_QUOTING_STYLE;
+  else
+    return CURVE_QUOTING_STYLE;
 }
 
 DEFUN ("substitute-command-keys", Fsubstitute_command_keys,
@@ -1045,6 +1052,10 @@ The default value nil acts like ‘curve’ if curved single quotes are
 displayable, and like ‘grave’ otherwise.  */);
   Vtext_quoting_style = Qnil;
 
+  DEFVAR_BOOL ("internal--text-quoting-flag", text_quoting_flag,
+               doc: /* If nil, a nil ‘text-quoting-style’ is treated as ‘grave’.  */);
+  /* Initialized by ‘main’.  */
+
   defsubr (&Sdocumentation);
   defsubr (&Sdocumentation_property);
   defsubr (&Ssnarf_documentation);