As suggested by jmc@, only include line and column numbers into messages

when they are meaningful, to avoid confusing stuff like this:
$ mandoc /dev/null
mandoc: /dev/null:0:1: FATAL: not a manual
Instead, just say:
mandoc: /dev/null: FATAL: not a manual

Another example this applies to is documents having a prologue,
but lacking a body.  Do not throw a FATAL error for these; instead,
issue a warning and show the empty document, in the man(7) case with
the same amount of blank lines as groff does.  Also downgrade mdoc(7)
documents having content before the first .Sh from FATAL to WARNING.

1 files changed, 8 insertions, 4 deletions

diff --git a/usr.bin/mandoc/main.c b/usr.bin/mandoc/main.c
index b0b35319bed..e754060cb60 100644
--- a/usr.bin/mandoc/main.c
+++ b/usr.bin/mandoc/main.c
@@ -1,4 +1,4 @@
-/*	$Id: main.c,v 1.91 2014/06/20 16:11:03 schwarze Exp $ */
+/*	$Id: main.c,v 1.92 2014/06/20 22:58:41 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010, 2011, 2012, 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -409,9 +409,13 @@ mmsg(enum mandocerr t, enum mandoclevel lvl,
 		const char *file, int line, int col, const char *msg)
 {
 
-	fprintf(stderr, "%s: %s:%d:%d: %s: %s", progname,
-	    file, line, col + 1,
-	    mparse_strlevel(lvl), mparse_strerror(t));
+	fprintf(stderr, "%s: %s:", progname, file);
+
+	if (line)
+		fprintf(stderr, "%d:%d:", line, col + 1);
+
+	fprintf(stderr, " %s: %s", mparse_strlevel(lvl),
+	    mparse_strerror(t));
 
 	if (msg)
 		fprintf(stderr, ": %s", msg);