fixes #4756 (#5557)

2017-03-17 18:11:37 +02:00 · 2017-03-17 18:11:37 +02:00 · a20a8e6adb
commit a20a8e6adb
parent d701de5733
2 changed files with 22 additions and 2 deletions
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@ -1086,8 +1086,12 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
  of tyBuiltInTypeClass:
    considerPreviousT:
      let targetKind = f.sons[0].kind
-      if targetKind == a.skipTypes({tyRange, tyGenericInst, tyBuiltInTypeClass, tyAlias}).kind or
-         (targetKind in {tyProc, tyPointer} and a.kind == tyNil):
+      let effectiveArgType = a.skipTypes({tyRange, tyGenericInst,
+                                          tyBuiltInTypeClass, tyAlias})
+      let typeClassMatches = targetKind == effectiveArgType.kind and
+                             not effectiveArgType.isEmptyContainer
+      if typeClassMatches or
+        (targetKind in {tyProc, tyPointer} and effectiveArgType.kind == tyNil):
        put(c, f, a)
        return isGeneric
      else: