From 5efa203c22ba4b49f2366f71d1104c2aaf37b144 Mon Sep 17 00:00:00 2001
From: k-hara <k.hara.pg@gmail.com>
Date: Wed, 27 Aug 2014 14:42:48 +0900
Subject: [PATCH] fix Issue 13379 - Latest dmd fails with recursive template
 expansion in std.regex

---
 src/template.c            | 28 ++++++++++++---------------
 test/runnable/template9.d | 40 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 16 deletions(-)

diff --git a/src/template.c b/src/template.c
index cd19deae003b..70d9a919ef31 100644
--- a/src/template.c
+++ b/src/template.c
@@ -5946,10 +5946,15 @@ void TemplateInstance::semantic(Scope *sc, Expressions *fargs)
             }
 
             // If the first instantiation was in speculative context, but this is not:
-            if (!inst->tinst && inst->speculative && !(sc->flags & (SCOPEstaticif | SCOPEstaticassert | SCOPEcompile)))
+            if (!inst->tinst && inst->speculative &&
+                tinst && !(sc->flags & (SCOPEstaticif | SCOPEstaticassert | SCOPEcompile)))
             {
                 // Reconnect the chain if this instantiation is not in speculative context.
-                inst->tinst = tinst;
+                TemplateInstance *tix = tinst;
+                while (tix && tix != inst)
+                    tix = tix->tinst;
+                if (tix != inst)    // Bugzilla 13379: Prevent circular chain
+                    inst->tinst = tinst;
             }
 
 #if LOG
@@ -6279,8 +6284,6 @@ void TemplateInstance::semantic(Scope *sc, Expressions *fargs)
         while (ti && !ti->deferred && ti->tinst)
         {
             ti = ti->tinst;
-            if (ti == tinst)
-                break;
             if (++nest > 500)
             {
                 global.gag = 0;            // ensure error message gets printed
@@ -7823,21 +7826,14 @@ bool TemplateInstance::needsCodegen()
         }
     }
 
-    if (speculative)
+    for (TemplateInstance *ti = this; ti; ti = ti->tinst)
     {
-        //printf("\tti = %s spec = %d\n", toChars(), speculative);
-        TemplateInstance *ti = this;
-        while (ti->tinst && ti->tinst != this)
-        {
-            ti = ti->tinst;
-            //printf("\tti = %s spec = %d\n", ti->toChars(), ti->speculative);
-            if (!ti->speculative)
-                return true;
-        }
-        return false;
+        //printf("\tti = %s spec = %d\n", ti->toChars(), ti->speculative);
+        if (!ti->speculative)
+            return true;
     }
 
-    return true;
+    return false;
 }
 
 /* ======================== TemplateMixin ================================ */
diff --git a/test/runnable/template9.d b/test/runnable/template9.d
index feb9e5f12dc9..f6f66f9de589 100644
--- a/test/runnable/template9.d
+++ b/test/runnable/template9.d
@@ -4149,6 +4149,45 @@ void test13378()
     doSome13378(v);
 }
 
+/******************************************/
+// 13379
+
+void test13379()
+{
+    match13379("");
+}
+
+auto match13379(RegEx )(RegEx  re)
+if (is(RegEx == Regex13379!char))       // #1 Regex!char (speculative && tinst == NULL)
+{}
+auto match13379(String)(String re)
+{}
+
+struct Regex13379(Char)
+{
+    ShiftOr13379!Char kickstart;        // #2 ShiftOr!char (speculative && tinst == Regex!char)
+}
+struct ShiftOr13379(Char)
+{
+    this(ref Regex13379!Char re)        // #3 Regex!Char (speculative && tinst == ShiftOr!char)
+    {
+        uint n_length;
+        uint idx;
+        n_length = min13379(idx, n_length);
+    }
+}
+
+template MinType13379(T...)
+{
+    alias MinType13379 = T[0];
+}
+MinType13379!T min13379(T...)(T args)   // #4 MinType!uint (speculative && thist == ShiftOr!char)
+{
+    alias a = args[0];
+    alias b = args[$-1];
+    return cast(typeof(return)) (a < b ? a : b);
+}
+
 /******************************************/
 
 int main()
@@ -4253,6 +4292,7 @@ int main()
     test13299();
     test13374();
     test13378();
+    test13379();
 
     printf("Success\n");
     return 0;