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.

8 files changed, 42 insertions, 30 deletions

diff --git a/main.c b/main.c
index 00cdfb76..c1e5ba9f 100644
--- a/main.c
+++ b/main.c
@@ -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);
diff --git a/man.h b/man.h
index fd6b9f91..13fa660f 100644
--- a/man.h
+++ b/man.h
@@ -79,6 +79,7 @@ struct	man_meta {
 	char		*vol; /* `TH' volume */
 	char		*title; /* `TH' title (e.g., FOO) */
 	char		*source; /* `TH' source (e.g., GNU) */
+	int		 hasbody; /* document is not empty */
 };
 
 struct	man_node {
diff --git a/man_term.c b/man_term.c
index e1d9c488..409fd784 100644
--- a/man_term.c
+++ b/man_term.c
@@ -1061,7 +1061,8 @@ print_man_foot(struct termp *p, const void *arg)
 
 	term_fontrepl(p, TERMFONT_NONE);
 
-	term_vspace(p);
+	if (meta->hasbody)
+		term_vspace(p);
 
 	/*
 	 * Temporary, undocumented option to imitate mdoc(7) output.
@@ -1070,8 +1071,10 @@ print_man_foot(struct termp *p, const void *arg)
 	 */
 
 	if ( ! p->mdocstyle) {
-		term_vspace(p);
-		term_vspace(p);
+		if (meta->hasbody) {
+			term_vspace(p);
+			term_vspace(p);
+		}
 		mandoc_asprintf(&title, "%s(%s)",
 		    meta->title, meta->msec);
 	} else if (meta->source) {
diff --git a/man_validate.c b/man_validate.c
index 0088e6f8..6ebf6cea 100644
--- a/man_validate.c
+++ b/man_validate.c
@@ -198,10 +198,12 @@ check_root(CHKARGS)
 	man->flags &= ~MAN_BLINE;
 	man->flags &= ~MAN_ELINE;
 
-	if (NULL == man->first->child) {
-		man_nmsg(man, n, MANDOCERR_NODOCBODY);
-		return(0);
-	} else if (NULL == man->meta.title) {
+	if (NULL == man->first->child)
+		man_nmsg(man, n, MANDOCERR_DOC_EMPTY);
+	else
+		man->meta.hasbody = 1;
+
+	if (NULL == man->meta.title) {
 		man_nmsg(man, n, MANDOCERR_TH_MISSING);
 
 		/*
diff --git a/mandoc.1 b/mandoc.1
index ddbcb38a..c8b7aa47 100644
--- a/mandoc.1
+++ b/mandoc.1
@@ -498,9 +498,7 @@ parser:
 .Sh DIAGNOSTICS
 Standard error messages reporting parsing errors are prefixed by
 .Pp
-.Sm off
-.D1 Ar file : line : column : \ level :
-.Sm on
+.D1 Nm Ns : Ar file : Ns Ar line : Ns Ar column : level :
 .Pp
 where the fields have the following meanings:
 .Bl -tag -width "column"
@@ -518,6 +516,12 @@ points to the first character of the word.
 The message level, printed in capital letters.
 .El
 .Pp
+The
+.Ar line
+and
+.Ar column
+fields are omitted when meaningless.
+.Pp
 Message levels have the following meanings:
 .Bl -tag -width "warning"
 .It Cm fatal
@@ -557,7 +561,7 @@ The
 utility may also print messages related to invalid command line arguments
 or operating system errors, for example when memory is exhausted or
 input files cannot be read.
-Such messages do not carry the prefix described above.
+Such messages may not carry the prefix described above.
 .Sh COMPATIBILITY
 This section summarises
 .Nm
diff --git a/mandoc.h b/mandoc.h
index 27e7bddc..5627d4d8 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -62,6 +62,8 @@ enum	mandocerr {
 
 	/* related to document structure */
 	MANDOCERR_SO, /* .so is fragile, better use ln(1) */
+	MANDOCERR_DOC_EMPTY, /* no document body */
+	MANDOCERR_SEC_BEFORE, /* content before the first section header */
 	MANDOCERR_NAMESECFIRST, /* NAME section must come first */
 	MANDOCERR_BADNAMESEC, /* bad NAME section contents */
 	MANDOCERR_SECOOO, /* sections out of conventional order */
@@ -161,7 +163,6 @@ enum	mandocerr {
 	MANDOCERR_SYNTCHILD, /* child violates parent syntax */
 	MANDOCERR_SYNTARGCOUNT, /* argument count wrong, violates syntax */
 	MANDOCERR_SOPATH, /* NOT IMPLEMENTED: .so with absolute path or ".." */
-	MANDOCERR_NODOCBODY, /* no document body */
 	MANDOCERR_NODOCPROLOG, /* no document prologue */
 	MANDOCERR_MEM, /* static buffer exhausted */
 
diff --git a/mdoc_validate.c b/mdoc_validate.c
index 0078f8cc..d62dc6cf 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -1645,15 +1645,15 @@ ebool(struct mdoc *mdoc)
 static int
 post_root(POST_ARGS)
 {
-	int		  erc;
+	int		  ret;
 	struct mdoc_node *n;
 
-	erc = 0;
+	ret = 1;
 
 	/* Check that we have a finished prologue. */
 
 	if ( ! (MDOC_PBODY & mdoc->flags)) {
-		erc++;
+		ret = 0;
 		mdoc_nmsg(mdoc, mdoc->first, MANDOCERR_NODOCPROLOG);
 	}
 
@@ -1662,17 +1662,13 @@ post_root(POST_ARGS)
 
 	/* Check that we begin with a proper `Sh'. */
 
-	if (NULL == n->child) {
-		erc++;
-		mdoc_nmsg(mdoc, n, MANDOCERR_NODOCBODY);
-	} else if (MDOC_BLOCK != n->child->type ||
-	    MDOC_Sh != n->child->tok) {
-		erc++;
-		/* Can this be lifted?  See rxdebug.1 for example. */
-		mdoc_nmsg(mdoc, n, MANDOCERR_NODOCBODY);
-	}
+	if (NULL == n->child)
+		mdoc_nmsg(mdoc, n, MANDOCERR_DOC_EMPTY);
+	else if (MDOC_BLOCK != n->child->type ||
+	    MDOC_Sh != n->child->tok)
+		mdoc_nmsg(mdoc, n->child, MANDOCERR_SEC_BEFORE);
 
-	return(erc ? 0 : 1);
+	return(ret);
 }
 
 static int
diff --git a/read.c b/read.c
index 482af0db..965d354e 100644
--- a/read.c
+++ b/read.c
@@ -106,6 +106,8 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 
 	/* related to document structure */
 	".so is fragile, better use ln(1)",
+	"no document body",
+	"content before the first section header",
 	"NAME section must come first",
 	"bad NAME section contents",
 	"sections out of conventional order",
@@ -204,7 +206,6 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	"child violates parent syntax",
 	"argument count wrong, violates syntax",
 	"NOT IMPLEMENTED: .so with absolute path or \"..\"",
-	"no document body",
 	"no document prologue",
 	"static buffer exhausted",
 
@@ -684,7 +685,7 @@ mparse_end(struct mparse *curp)
 	}
 
 	if ( ! (curp->mdoc || curp->man || curp->sodest)) {
-		mandoc_msg(MANDOCERR_NOTMANUAL, curp, 1, 0, NULL);
+		mandoc_msg(MANDOCERR_NOTMANUAL, curp, 0, 0, NULL);
 		curp->file_status = MANDOCLEVEL_FATAL;
 		return;
 	}