In man(7), when no explicit volume name is given, use the default

volume name for the respective manual section, just like in mdoc(7).
This gives us nicer page headers for cvs(1), lynx(1), tic(1),
mkhybrid(8), and many curses(3) manuals.

ok kristaps@

To not break compatibility, i wrote a corresponding patch for GNU troff
which Werner Lemberg accepted upstream at rev. 1.65 of:
http://cvs.savannah.gnu.org/viewvc/groff/tmac/an-old.tmac?root=groff

7 files changed, 23 insertions, 7 deletions

diff --git a/Makefile b/Makefile
index aa93b3b8..e6f8f2a3 100644
--- a/Makefile
+++ b/Makefile
@@ -173,7 +173,6 @@ LIBMDOC_OBJS	 = arch.o \
 		   mdoc_hash.o \
 		   mdoc_macro.o \
 		   mdoc_validate.o \
-		   msec.o \
 		   st.o \
 		   vol.o
 LIBMDOC_LNS	 = arch.ln \
@@ -184,7 +183,6 @@ LIBMDOC_LNS	 = arch.ln \
 		   mdoc_hash.ln \
 		   mdoc_macro.ln \
 		   mdoc_validate.ln \
-		   msec.ln \
 		   st.ln \
 		   vol.ln
 
@@ -206,12 +204,14 @@ LIBMANDOC_OBJS	 = $(LIBMAN_OBJS) \
 		   $(LIBROFF_OBJS) \
 		   chars.o \
 		   mandoc.o \
+		   msec.o \
 		   read.o
 LIBMANDOC_LNS	 = $(LIBMAN_LNS) \
 		   $(LIBMDOC_LNS) \
 		   $(LIBROFF_LNS) \
 		   chars.ln \
 		   mandoc.ln \
+		   msec.ln \
 		   read.ln
 
 COMPAT_OBJS	 = compat_getsubopt.o \
diff --git a/libmandoc.h b/libmandoc.h
index 7a123f0e..2a0c28df 100644
--- a/libmandoc.h
+++ b/libmandoc.h
@@ -49,6 +49,7 @@ char		*mandoc_normdate(struct mparse *, char *, int, int);
 int		 mandoc_eos(const char *, size_t, int);
 int		 mandoc_getcontrol(const char *, int *);
 int		 mandoc_strntoi(const char *, size_t, int);
+const char	*mandoc_a2msec(const char*);
 
 void	 	 mdoc_free(struct mdoc *);
 struct	mdoc	*mdoc_alloc(struct roff *, struct mparse *);
diff --git a/libmdoc.h b/libmdoc.h
index b7223c16..a23b2366 100644
--- a/libmdoc.h
+++ b/libmdoc.h
@@ -124,7 +124,6 @@ const char	 *mdoc_a2lib(const char *);
 const char	 *mdoc_a2st(const char *);
 const char	 *mdoc_a2arch(const char *);
 const char	 *mdoc_a2vol(const char *);
-const char	 *mdoc_a2msec(const char *);
 int		  mdoc_valid_pre(struct mdoc *, struct mdoc_node *);
 int		  mdoc_valid_post(struct mdoc *);
 enum margverr	  mdoc_argv(struct mdoc *, int, enum mdoct,
diff --git a/man.7 b/man.7
index fa7dbb0a..ff88058e 100644
--- a/man.7
+++ b/man.7
@@ -840,6 +840,19 @@ The
 .Sx \&sp
 macro does not accept negative values in mandoc.
 In GNU troff, this would result in strange behaviour.
+.It
+In page header lines, GNU troff versions up to and including 1.21
+only print
+.Ar volume
+names explicitly specified in the
+.Sx \&TH
+macro; mandoc and newer groff print the default volume name
+corresponding to the
+.Ar section
+number when no
+.Ar volume
+is given, like in
+.Xr mdoc 7 .
 .El
 .Sh SEE ALSO
 .Xr man 1 ,
diff --git a/man_validate.c b/man_validate.c
index 27ecd087..c63dcdfc 100644
--- a/man_validate.c
+++ b/man_validate.c
@@ -413,9 +413,13 @@ post_TH(CHKARGS)
 		m->meta.source = mandoc_strdup(n->string);
 
 	/* TITLE MSEC DATE SOURCE ->VOL<- */
+	/* If missing, use the default VOL name for MSEC. */
 
 	if (n && (n = n->next))
 		m->meta.vol = mandoc_strdup(n->string);
+	else if ('\0' != m->meta.msec[0] &&
+	    (NULL != (p = mandoc_a2msec(m->meta.msec))))
+		m->meta.vol = mandoc_strdup(p);
 
 	/*
 	 * Remove the `TH' node after we've processed it for our
diff --git a/mdoc_validate.c b/mdoc_validate.c
index f5158b01..7dc24961 100644
--- a/mdoc_validate.c
+++ b/mdoc_validate.c
@@ -2084,7 +2084,7 @@ post_dt(POST_ARGS)
 	 *       arch = NULL
 	 */
 
-	cp = mdoc_a2msec(nn->string);
+	cp = mandoc_a2msec(nn->string);
 	if (cp) {
 		mdoc->meta.vol = mandoc_strdup(cp);
 		mdoc->meta.msec = mandoc_strdup(nn->string);
diff --git a/msec.c b/msec.c
index 906534be..14b52c00 100644
--- a/msec.c
+++ b/msec.c
@@ -21,15 +21,14 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "mdoc.h"
 #include "mandoc.h"
-#include "libmdoc.h"
+#include "libmandoc.h"
 
 #define LINE(x, y) \
 	if (0 == strcmp(p, x)) return(y);
 
 const char *
-mdoc_a2msec(const char *p)
+mandoc_a2msec(const char *p)
 {
 
 #include "msec.in"