[src/trunk]: src/usr.bin/make make(1): document non-obvious special case in E...

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

details:   https://anonhg.NetBSD.org/src/rev/0427c89a8b69
branches:  trunk
changeset: 945959:0427c89a8b69
user:      rillig <rillig%NetBSD.org@localhost>
date:      Wed Nov 11 07:34:55 2020 +0000

description:
make(1): document non-obvious special case in EvalNotEmpty

diffstat:

 usr.bin/make/cond.c |  9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diffs (30 lines):

diff -r 4cdb12ef7265 -r 0427c89a8b69 usr.bin/make/cond.c
--- a/usr.bin/make/cond.c       Wed Nov 11 07:30:11 2020 +0000
+++ b/usr.bin/make/cond.c       Wed Nov 11 07:34:55 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cond.c,v 1.204 2020/11/11 07:13:42 rillig Exp $        */
+/*     $NetBSD: cond.c,v 1.205 2020/11/11 07:34:55 rillig Exp $        */
 
 /*
  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
@@ -93,7 +93,7 @@
 #include "dir.h"
 
 /*     "@(#)cond.c     8.2 (Berkeley) 1/2/94"  */
-MAKE_RCSID("$NetBSD: cond.c,v 1.204 2020/11/11 07:13:42 rillig Exp $");
+MAKE_RCSID("$NetBSD: cond.c,v 1.205 2020/11/11 07:34:55 rillig Exp $");
 
 /*
  * The parsing of conditional expressions is based on this grammar:
@@ -536,7 +536,10 @@
     if (TryParseNumber(value, &num))
        return num != 0.0;
 
-    /* For .if ${...}, check for non-empty string. */
+    /* For .if ${...}, check for non-empty string.  This is different from
+     * the evaluation function from that .if variant, which would test
+     * whether a variable of the given name were defined. */
+    /* XXX: Whitespace should count as empty, just as in ParseEmptyArg. */
     if (par->if_info->form[0] == '\0')
        return value[0] != '\0';