fix Issue 10664 - Win64: exception handling does not work with COMDAT…

… folding

src/dmd/s2ir.d

@@ -1105,6 +1105,24 @@ private extern (C++) class S2irVisitor : Visitor
                     bcatch.Bcatchtype = toSymbol(cs.type.toBasetype());
                 tryblock.appendSucc(bcatch);
                 block_goto(blx, BCjcatch, null);
+
+                if (cs.type && irs.params.isWindows && irs.params.is64bit) // Win64
+                {
+                    /* The linker will attempt to merge together identical functions,
+                     * even if the catch types differ. So add a reference to the
+                     * catch type here.
+                     * https://issues.dlang.org/show_bug.cgi?id=10664
+                     */
+                    auto tc = cs.type.toBasetype().isTypeClass();
+                    if (!tc.sym.vclassinfo)
+                        tc.sym.vclassinfo = TypeInfoClassDeclaration.create(tc);
+                    auto sinfo = toSymbol(tc.sym.vclassinfo);
+                    elem* ex = el_var(sinfo);
+                    ex.Ety = mTYvolatile | TYnptr;
+                    ex = el_una(OPind, TYint, ex);
+                    block_appendexp(irs.blx.curblock, ex);
+                }
+
                 if (cs.handler !is null)
                 {
                     StmtState catchState = StmtState(stmtstate, s);

test/runnable/test4.d

@@ -1425,6 +1425,46 @@ void test59()
 }
 
 
+/* ================================ */
+// https://issues.dlang.org/show_bug.cgi?id=10664
+
+Exception collectExceptionE(int delegate () expression, ref int result)
+{
+    try
+    {
+        result = expression();
+    }
+    catch (Exception e)
+    {
+        return e;
+    }
+    return null;
+}
+
+RangeError collectExceptionR(int delegate () expression, ref int result)
+{
+    try
+    {
+        result = expression();
+    }
+    catch (RangeError e)
+    {
+        return e;
+    }
+    return null;
+}
+
+void test10664()
+{
+    int b;
+    int foo() { throw new Exception("blah"); }
+    assert(collectExceptionE(&foo, b));
+
+    int[] a = new int[3];
+    int goo() { return a[4]; }
+    collectExceptionR(&goo, b);
+}
+
 /* ================================ */
 
 
@@ -1487,6 +1527,7 @@ int main()
     test57();
     test58();
     test59();
+    test10664();
 
     printf("Success\n");
     return 0;