Don't downcase system diagnostics' first letters

* etc/NEWS: Document this.
* lisp/emacs-lisp/bytecomp.el (byte-compile-file):
* lisp/ffap.el (find-file-at-point):
* lisp/files.el (insert-file-1):
* lisp/net/ange-ftp.el (ange-ftp-barf-if-not-directory)
(ange-ftp-copy-file-internal):
* lisp/progmodes/etags.el (visit-tags-table):
* lisp/url/url-dav.el (url-dav-delete-directory, url-dav-delete-file)
(url-dav-directory-files):
Keep diagnostics consistent with system's.
* lisp/erc/erc-dcc.el (erc-dcc-server):
* lisp/ffap.el (ffap-machine-p):
Ignore case while comparing diagnostics.
* src/fileio.c (report_file_errno): Don't downcase, and simplify.
Fixes: bug#19642

1 files changed, 10 insertions, 30 deletions

diff --git a/src/fileio.c b/src/fileio.c
index ff6720d4ae2..d0fd08a742e 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -186,37 +186,17 @@ void
 report_file_errno (char const *string, Lisp_Object name, int errorno)
 {
   Lisp_Object data = CONSP (name) || NILP (name) ? name : list1 (name);
-  Lisp_Object errstring;
-  char *str;
-
   synchronize_system_messages_locale ();
-  str = strerror (errorno);
-  errstring = code_convert_string_norecord (build_unibyte_string (str),
-					    Vlocale_coding_system, 0);
-
-  while (1)
-    switch (errorno)
-      {
-      case EEXIST:
-	xsignal (Qfile_already_exists, Fcons (errstring, data));
-	break;
-      default:
-	/* System error messages are capitalized.  Downcase the initial
-	   unless it is followed by a slash.  (The slash case caters to
-	   error messages that begin with "I/O" or, in German, "E/A".)  */
-	if (STRING_MULTIBYTE (errstring)
-	    && ! EQ (Faref (errstring, make_number (1)), make_number ('/')))
-	  {
-	    int c;
-
-	    str = SSDATA (errstring);
-	    c = STRING_CHAR ((unsigned char *) str);
-	    Faset (errstring, make_number (0), make_number (downcase (c)));
-	  }
-
-	xsignal (Qfile_error,
-		 Fcons (build_string (string), Fcons (errstring, data)));
-      }
+  char *str = strerror (errorno);
+  Lisp_Object errstring
+    = code_convert_string_norecord (build_unibyte_string (str),
+				    Vlocale_coding_system, 0);
+  Lisp_Object errdata = Fcons (errstring, data);
+
+  if (errorno == EEXIST)
+    xsignal (Qfile_already_exists, errdata);
+  else
+    xsignal (Qfile_error, Fcons (build_string (string), errdata));
 }
 
 /* Signal a file-access failure that set errno.  STRING describes the