Restore the traditional behaviour of the man(7) single-font

macros .B, .I, .SM, and .SB that the next-line scope extends
to the end of the next logical input line and is not extended
if that line ends with a \c (no-space) escape sequence.

While improving a loosely related feature in the man(7) .TP
macro, a regression entered the groff codebase in groff
commit 3549fd9f (28-Apr-2017) caused by the usual sloppiness
of Bjarni Ingi Gislason.  Since that time, groff wrongly had \c
extend next-line scope to a second line for these macros.
In man.c rev. 1.127 (25-Aug-2018) i synched mandoc behaviour
with groff in this respect, unfortunately failing to notice
the recent regression in groff.  The groff regression was
finally fixed by gbranden@ in commit 09c028f3 (07-Jun-2022).

With the present commit, mandoc is back in sync with both GNU and
Heirloom roff regarding the interaction of single-font macros with \c.

1 files changed, 9 insertions, 10 deletions

diff --git a/man.c b/man.c
index 7286a843..e72edcd7 100644
--- a/man.c
+++ b/man.c
@@ -76,16 +76,7 @@ man_hasc(char *start)
 void
 man_descope(struct roff_man *man, int line, int offs, char *start)
 {
-	/* Trailing \c keeps next-line scope open. */
-
-	if (start != NULL && man_hasc(start) != NULL)
-		return;
-
-	/*
-	 * Co-ordinate what happens with having a next-line scope open:
-	 * first close out the element scopes (if applicable),
-	 * then close out the block scope (also if applicable).
-	 */
+	/* First close out all next-line element scopes, if any. */
 
 	if (man->flags & MAN_ELINE) {
 		while (man->last->parent->type != ROFFT_ROOT &&
@@ -93,6 +84,14 @@ man_descope(struct roff_man *man, int line, int offs, char *start)
 			man_unscope(man, man->last->parent);
 		man->flags &= ~MAN_ELINE;
 	}
+
+	/* Trailing \c keeps next-line block scope open. */
+
+	if (start != NULL && man_hasc(start) != NULL)
+		return;
+
+	/* Close out the next-line block scope, if there is one. */
+
 	if ( ! (man->flags & MAN_BLINE))
 		return;
 	man_unscope(man, man->last->parent);