[master] ee29af937 Teach libvcc how to set STRING += STRING;

[Dridi Boukelmoune]

commit ee29af937a898d549287125b96c66688c68a829e
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Tue Nov 5 18:24:00 2019 +0100

    Teach libvcc how to set STRING += STRING;
    
    Refs #3100

diff --git a/bin/varnishtest/tests/v00018.vtc b/bin/varnishtest/tests/v00018.vtc
index 3ce6bd051..cd5fc41db 100644
--- a/bin/varnishtest/tests/v00018.vtc
+++ b/bin/varnishtest/tests/v00018.vtc
@@ -27,11 +27,6 @@ varnish v1 -errvcl {Expected '=' got '+='} {
 	sub vcl_backend_fetch { set bereq.backend += b; }
 }
 
-varnish v1 -errvcl {Expected '=' got '+='} {
-	backend b { .host = "127.0.0.1"; }
-	sub vcl_recv { set req.url += now; }
-}
-
 varnish v1 -errvcl {Expected ';' got 'if'} {
 	backend b { .host = "127.0.0.1"; }
 	/* XXX: This should not really be an synth */
diff --git a/lib/libvcc/vcc_action.c b/lib/libvcc/vcc_action.c
index e4ccd2e10..9d7f621cc 100644
--- a/lib/libvcc/vcc_action.c
+++ b/lib/libvcc/vcc_action.c
@@ -80,6 +80,7 @@ static const struct arith {
 	{ DURATION,	T_DIV,		REAL, "\v / " },
 	{ DURATION,	'=',		DURATION },
 	{ DURATION,	0,		DURATION },
+	{ STRING,	T_INCR,		STRING, "\v,\n" },
 	{ VOID,		'=',		VOID }
 };