make: avoid segfault on parse error

["Simon J. Gerraty" <sjg%crufty.net@localhost>]

While trying to trick make into handling something like:

VAR += ${${X:U0} > 0:?Use $X:}

I came accross the need for something like this.

Index: parse.c
===================================================================
RCS file: /cvsroot/src/usr.bin/make/parse.c,v
retrieving revision 1.147
diff -u -p -r1.147 parse.c
--- parse.c     6 Oct 2008 22:09:21 -0000       1.147
+++ parse.c     21 Oct 2008 18:19:01 -0000
@@ -392,7 +392,7 @@ ParseVErrorInternal(FILE *f, const char 
 
        (void)fprintf(f, "%s: \"", progname);
 
-       if (*cfname != '/' && strcmp(cfname, "(stdin)") != 0) {
+       if (*cfname != '/' && *cfname != '(') {
                char *cp;
                const char *dir;
 
@@ -471,6 +471,15 @@ Parse_Error(int type, const char *fmt, .
        va_list ap;
 
        va_start(ap, fmt);
+       if (curFile == (IFile *)NIL) {
+               /* avoid segfault */
+               static IFile intFile = {
+                       .fname = "(unknown)",
+                       .lineno = 0,
+                       .fd = -1,
+               };
+               curFile = &intFile;
+       }
        ParseVErrorInternal(stderr, curFile->fname, curFile->lineno,
                    type, fmt, ap);
        va_end(ap);
Index: unit-tests/cond1
===================================================================
RCS file: /cvsroot/src/usr.bin/make/unit-tests/cond1,v
retrieving revision 1.3
diff -u -p -r1.3 cond1
--- unit-tests/cond1    13 Apr 2004 16:06:23 -0000      1.3
+++ unit-tests/cond1    21 Oct 2008 18:19:01 -0000
@@ -100,3 +100,4 @@ all:
        @echo "A='$A' B='$B' C='$C' o='$o,${o2}'"
        @echo "Passed:${.newline} ${Ok:S/,/${.newline}/}"
        @echo "${NUMBERS:@n@$n is ${("${PRIMES:M$n}" == ""):?not:} 
prime${.newline}@}"
+       @echo "${"${NoSuch:U0}" > 0:?OK:No}"
Index: unit-tests/test.exp
===================================================================
RCS file: /cvsroot/src/usr.bin/make/unit-tests/test.exp,v
retrieving revision 1.25
diff -u -p -r1.25 test.exp
--- unit-tests/test.exp 15 May 2008 21:05:55 -0000      1.25
+++ unit-tests/test.exp 21 Oct 2008 18:19:01 -0000
@@ -20,6 +20,9 @@ Passed:
 4 is not prime
 5 is  prime
 
+make: "(unknown)" line 0: warning: String comparison operator should be either 
== or !=
+make: Bad conditional expression `"0" > 0' in "0" > 0?OK:No
+
 UT_DOLLAR=This is $UT_FU
 UT_FOO=foobar is fubar
 UT_FU=fubar