[groff] 03/31: tbl(1): Caution users re: conditional tbl content.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit 56e038cbe16079ea01a9ba1fcd30c2b0db9659f8
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Thu May 27 15:00:15 2021 +1000

    tbl(1): Caution users re: conditional tbl content.
    
    * src/preproc/tbl/tbl.1.man (Miscellaneous): Add paragraph cautioning
      users against making tbl(1) tables conditional document content.
---
 ChangeLog                 |  6 ++++++
 src/preproc/tbl/tbl.1.man | 30 ++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 4ece993..6c58dd4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2021-05-27  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       * src/preproc/tbl/tbl.1.man (Miscellaneous): Add paragraph
+       cautioning users against making tbl(1) tables conditional
+       document content.
+
 2021-05-25  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        Add style warnings for man(7) documents with input lines that
diff --git a/src/preproc/tbl/tbl.1.man b/src/preproc/tbl/tbl.1.man
index 3747122..370f384 100644
--- a/src/preproc/tbl/tbl.1.man
+++ b/src/preproc/tbl/tbl.1.man
@@ -985,6 +985,36 @@ instead of the standard call to the
 macro.
 .
 .
+.LP
+Using
+.I tbl
+macros within conditional input
+(that is,
+contingent upon an
+.BR .if ,
+.BR .ie ,
+.BR .el ,
+or
+.B .while
+request)
+can result in misleading line numbers in subsequent diagnostics.
+.
+.I tbl
+unconditionally injects its output into the source document,
+but the conditional branch containing it may not be taken,
+and if it is not,
+the
+.B .lf
+requests that
+.I tbl
+injects to restore the source line number cannot take effect.
+.
+Consider copying the input line counter register
+.B .c
+and restoring its value at a convenient location after applicable
+arithmetic.
+.
+.
 .\" ====================================================================
 .SS "Interaction with \f[I]\%@g@eqn\f[]"
 .\" ====================================================================