Rbrack: rbrack,
		}
	default:
		return &ast.IndexListExpr{
			X:       x,
			Lbrack:  lbrack,
			Indices: indices,
			Rbrack:  rbrack,
		}
	}
}

// IsTypeParam reports whether t is a type parameter (or an alias of one).
func IsTypeParam(t types.Type) bool {
	_, ok := aliases.Unalias(t).(*types.TypeParam)
	return ok
}

// GenericAssignableTo is a generalization of types.AssignableTo that

	// and their pointer base types are not type parameters"
	if V, ok := V.(*Pointer); ok {
		if T, ok := T.(*Pointer); ok {
			if IdenticalIgnoreTags(under(V.base), under(T.base)) && !isTypeParam(V.base) && !isTypeParam(T.base) {
				return true
			}
		}
	}

	// "V and T are both integer or floating point types"
	if isIntegerOrFloat(Vu) && isIntegerOrFloat(Tu) {
		return true
	}

	return ok
}

// isNonTypeParamInterface reports whether t is an interface type but not a type parameter.
func isNonTypeParamInterface(t Type) bool {
	return !isTypeParam(t) && IsInterface(t)
}

// isTypeParam reports whether t is a type parameter.
func isTypeParam(t Type) bool {
	_, ok := Unalias(t).(*TypeParam)
	return ok
}

// hasEmptyTypeset reports whether t is a type parameter with an empty type set.

		// Multiword data structures are effectively structs
		// in which each element has size WordSize.
		// Type parameters lead to variable sizes/alignments;
		// StdSizes.Alignof won't be called for them.
		assert(!isTypeParam(T))
		return s.WordSize
	case *Basic:
		// Strings are like slices and interfaces.
		if t.Info()&IsString != 0 {
			return s.WordSize
		}
	case *TypeParam, *Union:
		panic("unreachable")
	}

	return ok
}

// isNonTypeParamInterface reports whether t is an interface type but not a type parameter.
func isNonTypeParamInterface(t Type) bool {
	return !isTypeParam(t) && IsInterface(t)
}

// isTypeParam reports whether t is a type parameter.
func isTypeParam(t Type) bool {
	_, ok := Unalias(t).(*TypeParam)
	return ok
}

// hasEmptyTypeset reports whether t is a type parameter with an empty type set.

		// Multiword data structures are effectively structs
		// in which each element has size WordSize.
		// Type parameters lead to variable sizes/alignments;
		// StdSizes.Alignof won't be called for them.
		assert(!isTypeParam(T))
		return s.WordSize
	case *Basic:
		// Strings are like slices and interfaces.
		if t.Info()&IsString != 0 {
			return s.WordSize
		}
	case *TypeParam, *Union:
		panic("unreachable")
	}

	// and their pointer base types are not type parameters"
	if V, ok := V.(*Pointer); ok {
		if T, ok := T.(*Pointer); ok {
			if IdenticalIgnoreTags(under(V.base), under(T.base)) && !isTypeParam(V.base) && !isTypeParam(T.base) {
				return true
			}
		}
	}

	// "V and T are both integer or floating point types"
	if isIntegerOrFloat(Vu) && isIntegerOrFloat(Tu) {
		return true
	}

		S := x.typ
		var T Type
		if s, _ := coreType(S).(*Slice); s != nil {
			T = s.elem
		} else {
			var cause string
			switch {
			case x.isNil():
				cause = "have untyped nil"
			case isTypeParam(S):
				if u := coreType(S); u != nil {
					cause = check.sprintf("%s has core type %s", x, u)
				} else {
					cause = check.sprintf("%s has no core type", x)
				}
			default:

		// Multiword data structures are effectively structs
		// in which each element has size WordSize.
		// Type parameters lead to variable sizes/alignments;
		// StdSizes.Alignof won't be called for them.
		assert(!isTypeParam(T))
		return s.WordSize
	case *Basic:
		// Strings are like slices and interfaces.
		if t.Info()&IsString != 0 {
			return s.WordSize
		}
	case *TypeParam, *Union:
		panic("unreachable")
	}

		// Multiword data structures are effectively structs
		// in which each element has size WordSize.
		// Type parameters lead to variable sizes/alignments;
		// StdSizes.Alignof won't be called for them.
		assert(!isTypeParam(T))
		return s.WordSize
	case *Basic:
		// Strings are like slices and interfaces.
		if t.Info()&IsString != 0 {
			return s.WordSize
		}
	case *TypeParam, *Union:
		panic("unreachable")
	}