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/main.c b/main.c
index c1497761..f7f107a1 100644
--- a/main.c
+++ b/main.c
@@ -1,4 +1,4 @@
-/*	$Id: main.c,v 1.174 2014/06/20 16:11:42 schwarze Exp $ */
+/*	$Id: main.c,v 1.175 2014/06/20 23:02:31 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010, 2011, 2012, 2014 Ingo Schwarze <schwarze@openbsd.org>
@@ -408,9 +408,13 @@ 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);