Doc fixes for compile.el

* lisp/progmodes/compile.el (compilation-first-column)
(compilation-error-screen-columns): Doc fixes.
* etc/NEWS: Related markup.

1 files changed, 8 insertions, 2 deletions

diff --git a/lisp/progmodes/compile.el b/lisp/progmodes/compile.el
index d477569fb2d..6c48eee7f4b 100644
--- a/lisp/progmodes/compile.el
+++ b/lisp/progmodes/compile.el
@@ -78,7 +78,10 @@ after `call-process' inserts the grep output into the buffer.")
 This is bound to a buffer position before running `compilation-filter-hook'.")
 
 (defvar compilation-first-column 1
-  "*This is how compilers number the first column, usually 1 or 0.")
+  "*This is how compilers number the first column, usually 1 or 0.
+If this is buffer-local in the destination buffer, Emacs obeys
+that value, otherwise it uses the value in the *compilation*
+buffer.  This enables a major-mode to specify its own value.")
 
 (defvar compilation-parse-errors-filename-function nil
   "Function to call to post-process filenames while parsing error messages.
@@ -547,7 +550,10 @@ Otherwise they are interpreted as character positions, with
 each character occupying one column.
 The default is to use screen columns, which requires that the compilation
 program and Emacs agree about the display width of the characters,
-especially the TAB character."
+especially the TAB character.
+If this is buffer-local in the destination buffer, Emacs obeys
+that value, otherwise it uses the value in the *compilation*
+buffer.  This enables a major-mode to specify its own value."
   :type 'boolean
   :group 'compilation
   :version "20.4")