From 704e9579f785a42c3950f911b7ee16a4c1916b5e Mon Sep 17 00:00:00 2001
From: David Anderson <dvander@alliedmods.net>
Date: Sat, 8 Nov 2014 20:27:39 -0800
Subject: [PATCH] Fix comparisons of derived tags (bug 6239).

---
 sourcepawn/compiler/sc.h                       |  1 +
 sourcepawn/compiler/sc3.cpp                    |  4 ++--
 .../compiler/tests/ok-coerce-on-operators.sp   | 18 ++++++++++++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 sourcepawn/compiler/tests/ok-coerce-on-operators.sp

diff --git a/sourcepawn/compiler/sc.h b/sourcepawn/compiler/sc.h
index b46a6baa..5b611599 100644
--- a/sourcepawn/compiler/sc.h
+++ b/sourcepawn/compiler/sc.h
@@ -647,6 +647,7 @@ char *itoh(ucell val);
 #define MATCHTAG_COERCE       0x1 // allow coercion
 #define MATCHTAG_SILENT       0x2 // silence the error(213) warning
 #define MATCHTAG_COMMUTATIVE  0x4 // order does not matter
+#define MATCHTAG_DEDUCE       0x8 // correct coercion
 
 /* function prototypes in SC3.C */
 int check_userop(void (*oper)(void),int tag1,int tag2,int numparam,
diff --git a/sourcepawn/compiler/sc3.cpp b/sourcepawn/compiler/sc3.cpp
index c8584e87..1d70fe67 100644
--- a/sourcepawn/compiler/sc3.cpp
+++ b/sourcepawn/compiler/sc3.cpp
@@ -550,7 +550,7 @@ int matchtag(int formaltag, int actualtag, int flags)
     return TRUE;
   }
 
-  if (flags & MATCHTAG_COERCE) {
+  if (flags & (MATCHTAG_COERCE|MATCHTAG_DEDUCE)) {
     // See if the tag has a methodmap associated with it. If so, see if the given
     // tag is anywhere on the inheritance chain.
     methodmap_t *map = methodmap_find_by_tag(actualtag);
@@ -888,7 +888,7 @@ static void plnge2(void (*oper)(void),
     } else {
       // For the purposes of tag matching, we consider the order to be irrelevant.
       if (!checktag_string(lval1, lval2))
-        matchtag(lval1->tag, lval2->tag, MATCHTAG_COMMUTATIVE);
+        matchtag(lval1->tag, lval2->tag, MATCHTAG_COMMUTATIVE|MATCHTAG_DEDUCE);
       (*oper)();                /* do the (signed) operation */
       lval1->ident=iEXPRESSION;
     } /* if */
diff --git a/sourcepawn/compiler/tests/ok-coerce-on-operators.sp b/sourcepawn/compiler/tests/ok-coerce-on-operators.sp
new file mode 100644
index 00000000..643124dd
--- /dev/null
+++ b/sourcepawn/compiler/tests/ok-coerce-on-operators.sp
@@ -0,0 +1,18 @@
+enum Handle {
+	INVALID_HANDLE,
+};
+
+methodmap Handle {};
+methodmap ArrayList < Handle {};
+
+public void MyCommand()
+{
+    ArrayList myList;
+    if (INVALID_HANDLE == myList)
+    {
+    }
+    if (myList == INVALID_HANDLE)
+    {
+    }
+}
+