fixes #2659

tests/ccgbugs/tgeneric_closure.nim

@@ -0,0 +1,28 @@
+
+
+# bug 2659
+
+type
+  GenProcType[T,U] = proc(x:T, y:var U)
+  IntProcType = proc(x:int, y:var int)
+
+proc mult(x:int, y:var int) =
+  y = 2 * x
+
+when isMainModule:
+
+  var input = 1
+  var output = 0
+
+  var someIntProc:IntProcType = mult
+  var someGenProc:GenProcType[int,int] = mult
+
+  mult(input, output)
+  echo output
+
+  someIntProc(input, output)
+  echo output
+
+  # Uncommenting causes an error in the C compiler.
+  someGenProc(input, output)
+  echo output