Re: bin/43821: make: longstanding bug with loop variables

[David Holland <dholland-bugs%netbsd.org@localhost>]

The following reply was made to PR bin/43821; it has been noted by GNATS.

From: David Holland <dholland-bugs%netbsd.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: bin/43821: make: longstanding bug with loop variables
Date: Sat, 9 Oct 2010 21:03:41 +0000

 On Wed, Sep 01, 2010 at 09:50:04AM +0000, David Laight wrote:
  >  The 'problem' is that the code that substitutes the loop variables
  >  into the loop body before the body is parsed (yes it does work that way)
  >  doesn't identify empty(...) as equivalent to $(...) and modify the text.
 
 ...which it can't without doing a full parse.
 
  >  Since empty() is just a comparison against "" there is a trivial
  >  work around.
  >  
  >  A better fix is to rework the .for handling (again) so that the loop
  >  control variables are put into the main symbol table for the first
  >  pass processing, and the textual substitution done when lines are saved.
  >  eg for variable assignments (except :=) and shell commands.
 
 I think that's going to turn into a nightmare. I think the only
 reasonable approach for this (and many other related problems) is to
 tokenize and parse first before substituting anything, as I've
 suggested before. Unfortunately, it's a huge undertaking.
 
 -- 
 David A. Holland
 dholland%netbsd.org@localhost