[groff] 71/127: [mm]: Add more error checking to `IND` macro.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 527d89374c6d5e043ce33f9c5bd7a902ff23921f
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Fri Jun 30 18:51:28 2023 -0500

    [mm]: Add more error checking to `IND` macro.
    
    * contrib/mm/m.tmac (IND): Throw error if vertical drawing position is
      negative.  (What page number can be recorded when that is the case?)
      Thanks to Damian McGuckin for raising this scenario.
---
 contrib/mm/ChangeLog | 6 ++++++
 contrib/mm/m.tmac    | 1 +
 2 files changed, 7 insertions(+)

diff --git a/contrib/mm/ChangeLog b/contrib/mm/ChangeLog
index d4e544b16..a2febe13d 100644
--- a/contrib/mm/ChangeLog
+++ b/contrib/mm/ChangeLog
@@ -1,3 +1,9 @@
+2023-06-30 G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       * m.tmac (IND): Throw error if vertical drawing position is
+       negative.  (What page number can be recorded when that is the
+       case?)  Thanks to Damian McGuckin for raising this scenario.
+
 2023-06-30 G. Branden Robinson <g.branden.robinson@gmail.com>
 
        Trivially refactor.
diff --git a/contrib/mm/m.tmac b/contrib/mm/m.tmac
index 232dad8c1..8b77f2a96 100644
--- a/contrib/mm/m.tmac
+++ b/contrib/mm/m.tmac
@@ -3368,6 +3368,7 @@ exceeds depth of nested lists (\\n[li*lvl])
 .if !d ind*file .@error \\$0: no active index; call INITI first
 .if \\n[.$]<1 .@error \\$0: expected at least 1 argument, got \\n[.$]
 .if '\\$1'' .@error \\$0: cannot record empty index entry
+.if \\n[nl]<0 .@error \\$0: cannot record index entry when not on a page
 .ds ind*line \\$1
 .while \\n[.$]>0 \{\
 .      shift