[src/trunk]: src/usr.bin/make make(1): document the relation between VARE_ASS...

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/175c4c4cdaa2
branches:  trunk
changeset: 1016017:175c4c4cdaa2
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sat Nov 07 13:13:19 2020 +0000

description:
make(1): document the relation between VARE_ASSIGN and preserveUndefined

diffstat:

 usr.bin/make/nonints.h |  7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diffs (21 lines):

diff -r a8a8585ae46a -r 175c4c4cdaa2 usr.bin/make/nonints.h
--- a/usr.bin/make/nonints.h    Sat Nov 07 13:09:13 2020 +0000
+++ b/usr.bin/make/nonints.h    Sat Nov 07 13:13:19 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nonints.h,v 1.154 2020/11/07 10:16:19 rillig Exp $     */
+/*     $NetBSD: nonints.h,v 1.155 2020/11/07 13:13:19 rillig Exp $     */
 
 /*-
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -220,7 +220,10 @@
     /* Expand and evaluate variables during parsing. */
     VARE_WANTRES       = 1 << 1,
     /* In an assignment using the ':=' operator, keep '$$' as '$$' instead
-     * of reducing it to a single '$'. */
+     * of reducing it to a single '$'.
+     *
+     * See also preserveUndefined, which preserves subexpressions based on
+     * undefined variables; maybe that can be converted to a flag as well. */
     VARE_ASSIGN                = 1 << 2
 } VarEvalFlags;