case *Basic:
		if !isValid(u) {
			// error is reported elsewhere
			return &emptyInterface
		}
	case *Interface:
		if isTypeParam(bound) {
			// error is reported in Checker.collectTypeParams
			return &emptyInterface
		}
		ityp = u
	}

	// If we don't have an interface, wrap constraint into an implicit interface.
	if ityp == nil {
		ityp = NewInterfaceType(nil, []Type{bound})

	case *Basic:
		if !isValid(u) {
			// error is reported elsewhere
			return &emptyInterface
		}
	case *Interface:
		if isTypeParam(bound) {
			// error is reported in Checker.collectTypeParams
			return &emptyInterface
		}
		ityp = u
	}

	// If we don't have an interface, wrap constraint into an implicit interface.
	if ityp == nil {
		ityp = NewInterfaceType(nil, []Type{bound})

					versionErr = true
				}
				check.openScope(tdecl, "type parameters")
				defer check.closeScope()
				check.collectTypeParams(&alias.tparams, tdecl.TParamList)
			}

			rhs = check.definedType(tdecl.Type, obj)
			assert(rhs != nil)
			alias.fromRHS = rhs
			Unalias(alias) // resolve alias.actual
		} else {

					versionErr = true
				}
				check.openScope(tdecl, "type parameters")
				defer check.closeScope()
				check.collectTypeParams(&alias.tparams, tdecl.TypeParams)
			}

			rhs = check.definedType(tdecl.Type, obj)
			assert(rhs != nil)
			alias.fromRHS = rhs
			Unalias(alias) // resolve alias.actual
		} else {

			}
		}
	}

	if tparams != nil {
		// The parser will complain about invalid type parameters for methods.
		check.collectTypeParams(&sig.tparams, tparams)
	}

	// Use a temporary scope for all parameter declarations and then
	// squash that scope into the parent scope (and report any
	// redeclarations at that time).
	//

				got := measure(len(tparams), "type parameter")
				check.errorf(recvPar, BadRecv, "got %s, but receiver base type declares %d", got, len(recvTParams))
			}
		}
	}

	if ftyp.TypeParams != nil {
		check.collectTypeParams(&sig.tparams, ftyp.TypeParams)
		// Always type-check method type parameters but complain that they are not allowed.
		// (A separate check is needed when type-checking interface method signatures because