From 5920f0953c9e7f4683d8c6f90a15497c95870076 Mon Sep 17 00:00:00 2001
From: k-hara <k.hara.pg@gmail.com>
Date: Sat, 17 May 2014 16:33:13 +0900
Subject: [PATCH] fix Issue 12798 - constant folding should optimize subsequent
 concatenations

---
 src/optimize.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/optimize.c b/src/optimize.c
index ce7c76343b6f..d9ca87c50465 100644
--- a/src/optimize.c
+++ b/src/optimize.c
@@ -1212,6 +1212,21 @@ Expression *Expression_optimize(Expression *e, int result, bool keepLvalue)
             //printf("CatExp::optimize(%d) %s\n", result, e->toChars());
             e->e1 = e->e1->optimize(result);
             e->e2 = e->e2->optimize(result);
+
+            if (e->e1->op == TOKcat)
+            {
+                // Bugzilla 12798: optimize ((expr ~ str1) ~ str2)
+                CatExp *ce1 = (CatExp *)e->e1;
+                CatExp cex(e->loc, ce1->e2, e->e2);
+                cex.type = e->type;
+                Expression *ex = cex.optimize(result);
+                if (ex != &cex)
+                {
+                    e->e1 = ce1->e1;
+                    e->e2 = ex;
+                }
+            }
+
             ret = Cat(e->type, e->e1, e->e2);
             if (ret == EXP_CANT_INTERPRET)
                 ret = e;