[src/trunk]: src/usr.bin/make make(1): error out if .undef has not exactly 1 ...

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

details:   https://anonhg.NetBSD.org/src/rev/5ef1076e95c4
branches:  trunk
changeset: 979217:5ef1076e95c4
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sat Dec 19 22:10:17 2020 +0000

description:
make(1): error out if .undef has not exactly 1 argument

diffstat:

 usr.bin/make/unit-tests/directive-undef.exp |   6 +++-
 usr.bin/make/unit-tests/directive-undef.mk  |  38 +++++++++++++++++++++++++---
 usr.bin/make/var.c                          |  29 +++++++++++++++++++---
 3 files changed, 64 insertions(+), 9 deletions(-)

diffs (122 lines):

diff -r 03632cedf6c6 -r 5ef1076e95c4 usr.bin/make/unit-tests/directive-undef.exp
--- a/usr.bin/make/unit-tests/directive-undef.exp       Sat Dec 19 21:54:42 2020 +0000
+++ b/usr.bin/make/unit-tests/directive-undef.exp       Sat Dec 19 22:10:17 2020 +0000
@@ -1,1 +1,5 @@
-exit status 0
+make: "directive-undef.mk" line 14: The .undef directive requires exactly 1 argument
+make: "directive-undef.mk" line 24: The .undef directive requires exactly 1 argument
+make: Fatal errors encountered -- cannot continue
+make: stopped in unit-tests
+exit status 1
diff -r 03632cedf6c6 -r 5ef1076e95c4 usr.bin/make/unit-tests/directive-undef.mk
--- a/usr.bin/make/unit-tests/directive-undef.mk        Sat Dec 19 21:54:42 2020 +0000
+++ b/usr.bin/make/unit-tests/directive-undef.mk        Sat Dec 19 22:10:17 2020 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: directive-undef.mk,v 1.7 2020/12/19 20:35:39 rillig Exp $
+# $NetBSD: directive-undef.mk,v 1.8 2020/12/19 22:10:18 rillig Exp $
 #
 # Tests for the .undef directive.
 #
@@ -16,9 +16,39 @@
 .  warning $1$2$3
 .endif
 
-# Without any arguments, .undef tries to delete the variable with the empty
-# name, which never exists; see varname-empty.mk.
-.undef                         # oops: missing argument
+
+# Without any arguments, until var.c 1.736 from 2020-12-19, .undef tried
+# to delete the variable with the empty name, which never exists; see
+# varname-empty.mk.  Since var.c 1.737 from 2020-12-19, .undef complains
+# about a missing argument.
+.undef
+
+
+# Trying to delete the variable with the empty name is ok, it just won't
+# ever do anything since that variable is never defined.
+.undef ${:U}
+
+
+# The argument of .undef is a single word, delimited by whitespace, without
+# any possibility of escaping or having variable expressions containing
+# spaces.  This word is then expanded exactly once, and the expanded string
+# is the single variable name.  This allows variable names to contain spaces,
+# as well as unbalanced single and double quotes.
+1=             1
+2=             2
+3=             3
+${:U1 2 3}=    one two three
+VARNAMES=      1 2 3
+.undef ${VARNAMES}             # undefines the variable "1 2 3"
+.if defined(${:U1 2 3})
+.  error
+.endif
+.if ${1}${2}${3} != "123"      # these are still defined
+.  error
+.endif
+.undef 1
+.undef 2
+.undef 3
 
 
 # It must be possible to undefine variables whose name includes spaces.
diff -r 03632cedf6c6 -r 5ef1076e95c4 usr.bin/make/var.c
--- a/usr.bin/make/var.c        Sat Dec 19 21:54:42 2020 +0000
+++ b/usr.bin/make/var.c        Sat Dec 19 22:10:17 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: var.c,v 1.736 2020/12/19 20:47:24 rillig Exp $ */
+/*     $NetBSD: var.c,v 1.737 2020/12/19 22:10:17 rillig Exp $ */
 
 /*
  * Copyright (c) 1988, 1989, 1990, 1993
@@ -131,7 +131,7 @@
 #include "metachar.h"
 
 /*     "@(#)var.c      8.3 (Berkeley) 3/19/94" */
-MAKE_RCSID("$NetBSD: var.c,v 1.736 2020/12/19 20:47:24 rillig Exp $");
+MAKE_RCSID("$NetBSD: var.c,v 1.737 2020/12/19 22:10:17 rillig Exp $");
 
 /* A string that may need to be freed after use. */
 typedef struct FStr {
@@ -531,18 +531,39 @@
        Var_DeleteVar(name, ctxt);
 }
 
+/*
+ * Undefine a single variable from the global scope.  The argument is
+ * expanded once.
+ */
 void
 Var_Undef(char *arg)
 {
+       /*
+        * The argument must consist of exactly 1 word.  Accepting more than
+        * 1 word would have required to split the argument into several
+        * words, and such splitting is already done subtly different in many
+        * other places of make.
+        *
+        * Using Str_Words to split the words, followed by Var_Subst to expand
+        * each variable name once would make it impossible to undefine
+        * variables whose names contain space characters or unbalanced
+        * quotes or backslashes in arbitrary positions.
+        *
+        * Using Var_Subst on the whole argument and splitting the words
+        * afterwards using Str_Words would make it impossible to undefine
+        * variables whose names contain space characters.
+        */
        char *cp = arg;
 
        for (; !ch_isspace(*cp) && *cp != '\0'; cp++)
                continue;
+       if (cp == arg || *cp != '\0') {
+               Parse_Error(PARSE_FATAL,
+                   "The .undef directive requires exactly 1 argument");
+       }
        *cp = '\0';
 
        Var_Delete(arg, VAR_GLOBAL);
-       /* TODO: undefine all variables, not only the first */
-       /* TODO: use Str_Words, like everywhere else */
 }
 
 static Boolean