vcc: Give the REGEX treatment to ACL expressions

Except that we shouldn't start from expr0 since both use cases clearly
need expr4 parsing. Instead of making assumptions based on the type in
expr0, we split the final expression type check in its own function and
use it to confirm that we are matching a regex or an acl.

Fixes #3628

bin/varnishtest/tests/v00021.vtc

@@ -151,6 +151,15 @@ varnish v1 -errvcl {Symbols named 'vcl_*' are reserved.} {
 	}
 }
 
+# 3628
+varnish v1 -vcl {
+	backend be none;
+	acl foo { }
+	sub vcl_recv {
+		if (client.ip ~ foo || server.ip ~ foo) { }
+	}
+}
+
 varnish v1 -errvcl {Expression has type BOOL, expected ACL} {
 	sub vcl_recv {
 		if (client.ip ~ true) { }

lib/libvcc/vcc_expr.c

@@ -83,6 +83,8 @@ vcc_utype(vcc_type_t t)
 
 static void vcc_expr0(struct vcc *tl, struct expr **e, vcc_type_t fmt);
 static void vcc_expr_cor(struct vcc *tl, struct expr **e, vcc_type_t fmt);
+static void vcc_expr_typecheck(struct vcc *tl, struct expr **e, vcc_type_t fmt,
+    struct token *t1);
 
 static struct expr *
 vcc_new_expr(vcc_type_t fmt)
@@ -1107,12 +1109,16 @@ cmp_simple(struct vcc *tl, struct expr **e, const struct cmps *cp)
 static void v_matchproto_(cmp_f)
 cmp_regexp(struct vcc *tl, struct expr **e, const struct cmps *cp)
 {
+	struct token *t1;
 	struct expr *e2;
 	char buf[128];
 
 	*e = vcc_expr_edit(tl, STRING, "\vS", *e, NULL);
 	vcc_NextToken(tl);
-	vcc_expr0(tl, &e2, REGEX);
+	t1 = tl->t;
+	vcc_expr4(tl, &e2, REGEX);
+	ERRCHK(tl);
+	vcc_expr_typecheck(tl, &e2, REGEX, t1);
 	ERRCHK(tl);
 	bprintf(buf, "%sVRT_re_match(ctx, \v1, \v2)", cp->emit);
 	*e = vcc_expr_edit(tl, BOOL, buf, *e, e2);
@@ -1121,11 +1127,15 @@ cmp_regexp(struct vcc *tl, struct expr **e, const struct cmps *cp)
 static void v_matchproto_(cmp_f)
 cmp_acl(struct vcc *tl, struct expr **e, const struct cmps *cp)
 {
+	struct token *t1;
 	struct expr *e2;
 	char buf[256];
 
 	vcc_NextToken(tl);
-	vcc_expr0(tl, &e2, ACL);
+	t1 = tl->t;
+	vcc_expr4(tl, &e2, ACL);
+	ERRCHK(tl);
+	vcc_expr_typecheck(tl, &e2, ACL, t1);
 	ERRCHK(tl);
 	bprintf(buf, "%sVRT_acl_match(ctx, \v1, \v2)", cp->emit);
 	*e = vcc_expr_edit(tl, BOOL, buf, e2, *e);
@@ -1366,8 +1376,6 @@ vcc_expr0(struct vcc *tl, struct expr **e, vcc_type_t fmt)
 	t1 = tl->t;
 	if (fmt->stringform)
 		vcc_expr_cor(tl, e, STRINGS);
-	else if (fmt == REGEX)
-		vcc_expr4(tl, e, REGEX);
 	else
 		vcc_expr_cor(tl, e, fmt);
 	ERRCHK(tl);
@@ -1406,11 +1414,21 @@ vcc_expr0(struct vcc *tl, struct expr **e, vcc_type_t fmt)
 		ERRCHK(tl);
 	}
 
+	vcc_expr_typecheck(tl, e, fmt, t1);
+}
+
+static void
+vcc_expr_typecheck(struct vcc *tl, struct expr **e, vcc_type_t fmt,
+    struct token *t1)
+{
+
+	assert(fmt != VOID);
+	assert(fmt != STRINGS);
+
 	if (fmt != (*e)->fmt)  {
 		VSB_printf(tl->sb, "Expression has type %s, expected %s\n",
 		    vcc_utype((*e)->fmt), vcc_utype(fmt));
 		vcc_ErrWhere2(tl, t1, tl->t);
-		return;
 	}
 }