[groff] 06/12: [mm]: Validate state when `MULN`, `NCOL` called.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit b3b1c2a7440cff29ce762d0c637b16872153f838
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Fri Jun 21 09:44:25 2024 -0500

    [mm]: Validate state when `MULN`, `NCOL` called.
    
    * contrib/mm/m.tmac (NCOL): Validate package state, throwing warning if
      called when not in multi-column mode.
    
      (MULN): Validate package state, aborting with error if not in
      multi-column mode, rather than accessing undefined registers and
      spewing much noise about internal parameters if `-wreg` enabled.
---
 contrib/mm/ChangeLog | 8 ++++++++
 contrib/mm/m.tmac    | 5 ++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/contrib/mm/ChangeLog b/contrib/mm/ChangeLog
index 03423efeb..66a9a08c3 100644
--- a/contrib/mm/ChangeLog
+++ b/contrib/mm/ChangeLog
@@ -1,3 +1,11 @@
+2024-06-21  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       * m.tmac (NCOL): Validate package state, throwing warning if
+       called when not in multi-column mode.
+       (MULN): Validate package state, aborting with error if not in
+       multi-column mode, rather than accessing undefined registers and
+       spewing much noise about internal parameters if `-wreg` enabled.
+
 2024-06-15  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        * examples/story.mm: New file illustrates a "normal" document,
diff --git a/contrib/mm/m.tmac b/contrib/mm/m.tmac
index f1965d09c..f37592308 100644
--- a/contrib/mm/m.tmac
+++ b/contrib/mm/m.tmac
@@ -1672,8 +1672,10 @@ page
 .ll \\n[pg*column-size]u
 .\" .lt \\n[pg*column-size]u
 ..
-.\" begin a new column
+.\" begin a new column if using `2C` or `MC`
 .de NCOL
+.if \\n[pg*cols-per-page]<2 .@warning \\$0: not in multi-column mode; \
+breaking page
 .br
 .if \\n[nl]>\\n[pg*last-ncol] .nr pg*last-ncol \\n[nl]
 .pg@footer
@@ -1717,6 +1719,7 @@ page
 ..
 .\"-----------
 .de MULN
+.if \\n[pg*cols-per-page]<2 .@error \\$0: not in multi-column mode
 .if \\n[pg*mul-x]>=\\n[pg*mul-max-col] .@abort undefined column width \
 (pg*mul-x=\\n[pg*mul-x >= pg*mul-max-col=\\n[pg*mul-max])
 .br