implemented and documented the new typedesc binding rules

2 files changed, 13 insertions, 5 deletions

diff --git a/compiler/semtypes.nim b/compiler/semtypes.nim
index e5d9058b4..b02fa7c31 100644
--- a/compiler/semtypes.nim
+++ b/compiler/semtypes.nim
@@ -589,6 +589,8 @@ proc addParamOrResult(c: PContext, param: PSym, kind: TSymKind) =
   else:
     if sfGenSym notin param.flags: addDecl(c, param)
 
+let typedescId = getIdent"typedesc"
+
 proc liftParamType(c: PContext, procKind: TSymKind, genericParams: PNode,
                    paramType: PType, paramName: string,
                    info: TLineInfo, anon = false): PType =
@@ -636,6 +638,9 @@ proc liftParamType(c: PContext, procKind: TSymKind, genericParams: PNode,
       result = addImplicitGeneric(c.newTypeWithSons(tyExpr, paramType.sons))
   of tyTypeDesc:
     if tfUnresolved notin paramType.flags:
+      # naked typedescs are not bindOnce types
+      if paramType.sonsLen == 0 and paramTypId != nil and
+         paramTypId.id == typedescId.id: paramTypId = nil
       result = addImplicitGeneric(c.newTypeWithSons(tyTypeDesc, paramType.sons))
   of tyDistinct:
     if paramType.sonsLen == 1:
@@ -762,7 +767,7 @@ proc semProcTypeNode(c: PContext, n, genericParams: PNode,
         r.flags.incl tfRetType
       result.sons[0] = skipIntLit(r)
       res.typ = result.sons[0]
- 
+
 proc semStmtListType(c: PContext, n: PNode, prev: PType): PType =
   checkMinSonsLen(n, 1)
   var length = sonsLen(n)
@@ -1078,8 +1083,9 @@ proc semGenericParamList(c: PContext, n: PNode, father: PType = nil): PNode =
     if constraint.kind != nkEmpty:
       typ = semTypeNode(c, constraint, nil)
       if typ.kind != tyExpr or typ.len == 0:
-        if typ.len == 0 and typ.kind == tyTypeDesc:
-          typ = newTypeS(tyGenericParam, c)
+        if typ.kind == tyTypeDesc:
+          if typ.len == 0:
+            typ = newTypeS(tyTypeDesc, c)
         else:
           typ = semGenericConstraints(c, typ)
     
diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index 4483b1f8b..5766aa164 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -655,7 +655,7 @@ proc typeRel(c: var TCandidate, f, a: PType): TTypeRelation =
       result = typeRel(c, x, a) # check if it fits
   of tyTypeDesc:
     var prev = PType(idTableGet(c.bindings, f))
-    if prev == nil or true:
+    if prev == nil:
       if a.kind == tyTypeDesc:
         if f.sonsLen == 0:
           result = isGeneric
@@ -667,7 +667,9 @@ proc typeRel(c: var TCandidate, f, a: PType): TTypeRelation =
         result = isNone
     else:
       InternalAssert prev.sonsLen == 1
-      result = typeRel(c, prev.sons[0], a)
+      let toMatch = if tfUnresolved in f.flags: a
+                    else: a.sons[0]
+      result = typeRel(c, prev.sons[0], toMatch)
   of tyExpr, tyStmt:
     result = isGeneric
   of tyProxy: