revert a little bit, fix distinct types in static instantiation

compiler/semexprs.nim

@@ -394,11 +394,7 @@ proc semConv(c: PContext, n: PNode; flags: TExprFlags = {}, expectedType: PType
       targetType = targetType.base
   of tyAnything, tyUntyped, tyTyped:
     localError(c.config, n.info, "illegal type conversion to '$1'" % typeToString(targetType))
-  elif c.inGenericContext > 0 and targetType.containsGenericType and 
-      not (targetType.sym != nil and targetType.sym.magic != mNone):
-    result = semGenericStmt(c, n)
-    result.typ = makeTypeFromExpr(c, copyTree(result))
-    return
+  else: discard
 
   maybeLiftType(targetType, c, n[0].info)
 

compiler/semtypinst.nim

@@ -702,6 +702,7 @@ proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType =
     if not cl.allowMetaTypes and result.n != nil and
         result.base.kind != tyNone:
       result.n = cl.c.semConstExpr(cl.c, result.n)
+      result.n.typ = result.base
 
   of tyGenericInst, tyUserTypeClassInst:
     bailout()

compiler/sigmatch.nim

@@ -1969,6 +1969,10 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
   of tyFromExpr:
     # fix the expression, so it contains the already instantiated types
     if f.n == nil or f.n.kind == nkEmpty: return isGeneric
+    if c.c.inGenericContext > 0:
+      # need to delay until instantiation
+      # also prevent infinite recursion below
+      return isNone
     inc c.c.inGenericContext # to generate tyFromExpr again if unresolved
     let reevaluated = tryResolvingStaticExpr(c, f.n, allowCalls = true).typ
     dec c.c.inGenericContext
@@ -2180,7 +2184,10 @@ proc paramTypesMatchAux(m: var TCandidate, f, a: PType,
       return argSemantized
 
     if a.kind == tyStatic:
-      discard
+      if m.callee.kind == tyGenericBody and
+         a.n == nil and
+         tfGenericTypeParam notin a.flags:
+        return newNodeIT(nkType, argOrig.info, makeTypeFromExpr(c, arg))
     elif arg.kind != nkEmpty:
       var evaluated = c.semTryConstExpr(c, arg)
       if evaluated != nil: