[src/trunk]: src/usr.bin/make Fix parsing of nested variables during .for loop

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

details:   https://anonhg.NetBSD.org/src/rev/456293bcc292
branches:  trunk
changeset: 935398:456293bcc292
user:      sjg <sjg%NetBSD.org@localhost>
date:      Wed Jul 01 18:02:26 2020 +0000

description:
Fix parsing of nested variables during .for loop

Recent change to cond.c to avoid eval of unnecessary
terms had side effect on constructs like:

.for s in 1 2
.if defined(MAN$s) && !empty(MAN$s)
MAN+= ${MAN$s}
.endif
.endfor

resulting in MAN being flagged as recursive.

When Var_Parse encounters a variable within a variable name
we want to force it to be expanded.
But given the way get_mpt_arg calls Var_Parse we need to check
whether we actually started parsing a variable yet.

diffstat:

 usr.bin/make/unit-tests/varmisc.exp |   1 +
 usr.bin/make/unit-tests/varmisc.mk  |  16 ++++++++++++++--
 usr.bin/make/var.c                  |  15 ++++++++++-----
 3 files changed, 25 insertions(+), 7 deletions(-)

diffs (86 lines):

diff -r 818235e977b0 -r 456293bcc292 usr.bin/make/unit-tests/varmisc.exp
--- a/usr.bin/make/unit-tests/varmisc.exp       Wed Jul 01 17:57:14 2020 +0000
+++ b/usr.bin/make/unit-tests/varmisc.exp       Wed Jul 01 18:02:26 2020 +0000
@@ -22,4 +22,5 @@
 Version=123.456.789 == 123456789
 Literal=3.4.5 == 3004005
 We have target specific vars
+MAN= make.1
 exit status 0
diff -r 818235e977b0 -r 456293bcc292 usr.bin/make/unit-tests/varmisc.mk
--- a/usr.bin/make/unit-tests/varmisc.mk        Wed Jul 01 17:57:14 2020 +0000
+++ b/usr.bin/make/unit-tests/varmisc.mk        Wed Jul 01 18:02:26 2020 +0000
@@ -1,9 +1,9 @@
-# $Id: varmisc.mk,v 1.8 2017/01/31 18:56:35 sjg Exp $
+# $Id: varmisc.mk,v 1.9 2020/07/01 18:02:26 sjg Exp $
 #
 # Miscellaneous variable tests.
 
 all: unmatched_var_paren D_true U_true D_false U_false Q_lhs Q_rhs NQ_none \
-       strftime cmpv
+       strftime cmpv manok
 
 unmatched_var_paren:
        @echo ${foo::=foo-text}
@@ -60,3 +60,15 @@
        @echo Version=${Version} == ${Version:${M_cmpv}}
        @echo Literal=3.4.5 == ${3.4.5:L:${M_cmpv}}
        @echo We have ${${.TARGET:T}.only}
+
+# catch misshandling of nested vars in .for loop
+MAN=
+MAN1= make.1
+.for s in 1 2
+.if defined(MAN$s) && !empty(MAN$s)
+MAN+= ${MAN$s}
+.endif
+.endfor
+
+manok:
+       @echo MAN=${MAN}
diff -r 818235e977b0 -r 456293bcc292 usr.bin/make/var.c
--- a/usr.bin/make/var.c        Wed Jul 01 17:57:14 2020 +0000
+++ b/usr.bin/make/var.c        Wed Jul 01 18:02:26 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.224 2020/06/05 19:20:46 sjg Exp $    */
+/*     $NetBSD: var.c,v 1.225 2020/07/01 18:02:26 sjg Exp $    */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -69,14 +69,14 @@
  */
 
 #ifndef MAKE_NATIVE
-static char rcsid[] = "$NetBSD: var.c,v 1.224 2020/06/05 19:20:46 sjg Exp $";
+static char rcsid[] = "$NetBSD: var.c,v 1.225 2020/07/01 18:02:26 sjg Exp $";
 #else
 #include <sys/cdefs.h>
 #ifndef lint
 #if 0
 static char sccsid[] = "@(#)var.c      8.3 (Berkeley) 3/19/94";
 #else
-__RCSID("$NetBSD: var.c,v 1.224 2020/06/05 19:20:46 sjg Exp $");
+__RCSID("$NetBSD: var.c,v 1.225 2020/07/01 18:02:26 sjg Exp $");
 #endif
 #endif /* not lint */
 #endif
@@ -3859,12 +3859,17 @@
                break;
            }
            /*
-            * A variable inside a variable, expand
+            * A variable inside a variable, expand.
+            * If we really started looking at a variable
+            * (str[0] == '$'), then force VARF_WANTRES
+            * since we need the nested variable expanded to
+            * get the correct name to lookup.
             */
            if (*tstr == '$') {
                int rlen;
                void *freeIt;
-               char *rval = Var_Parse(tstr, ctxt, flags,  &rlen, &freeIt);
+               char *rval = Var_Parse(tstr, ctxt,
+                   flags|((*str == '$') ? VARF_WANTRES : 0),  &rlen, &freeIt);
                if (rval != NULL) {
                    Buf_AddBytes(&buf, strlen(rval), rval);
                }