MM 2.37 Short Paragraph Bug

[Larry Jones]

The current mm macros (2.37) have a long-standing problem with short
paragraphs.  For example, the input:

        .H 1 Bug
        .P
        one
        .P
        two
        .P
        three

results in:

       1.  Bug

       one two three

whereas it should, of course, produce:

       1.  Bug

       one
       
       two
       
       three

The problem is a simple and/or confusion when negated:

Index: contrib/mm/m.tmac
===================================================================
RCS file: /sources/groff/groff/contrib/mm/m.tmac,v
retrieving revision 2.37
diff -u -r2.37 m.tmac
--- contrib/mm/m.tmac   14 May 2010 04:40:33 -0000      2.37
+++ contrib/mm/m.tmac   30 May 2010 01:30:42 -0000
@@ -431,7 +431,7 @@
 .      tm Paragraph nl=\\n[nl], last=\\n[hd*last-pos]
 .      tm Paragraph .k=\\n[.k], hsize=\\n[hd*last-hsize]
 .\}
-.if !((\\n[nl]=\\n[hd*last-pos]):(\\n[hd*last-hsize]=\\n[.k])) \{\
+.if !((\\n[nl]=\\n[hd*last-pos])&(\\n[hd*last-hsize]=\\n[.k])) \{\
 .      if \\n[D]>2 .tm Paragraph set ind-flag=1
 .      nr address@hidden 1
 .      \" any collected unprinted text?
-- 
Larry Jones

You just can't ever be too careful. -- Calvin