go/test/typeparam/fact.go
Dan Scales 0fbde54ea6 [dev.typeparams] cmd/compile: allow generic funcs to call other generic funcs for stenciling
- Handle generic function calling itself or another generic function in
   stenciling. This is easy - after it is created, just scan an
   instantiated generic function for function instantiations (that may
   needed to be stenciled), just like non-generic functions. The types
   in the function instantiation will already have been set by the
   stenciling.

 - Handle OTYPE nodes in subster.node() (allows for generic type
   conversions).

 - Eliminated some duplicated work in subster.typ().

 - Added new test case fact.go that tests a generic function calling
   itself, and simple generic type conversions.

 - Cause an error if a generic function is to be exported (which we
   don't handle yet).

 - Fixed some suggested changes in the add.go test case that I missed in
   the last review.

Change-Id: I5d61704254c27962f358d5a3d2e0c62a5099f148
Reviewed-on: https://go-review.googlesource.com/c/go/+/290469
Trust: Dan Scales <danscales@google.com>
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
2021-02-08 19:32:55 +00:00

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659 B
Go

// run -gcflags=-G=3
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"fmt"
)
func fact[T interface { type float64 }](n T) T {
if n == T(1) {
return T(1)
}
return n * fact(n - T(1))
}
func main() {
got := fact(4.0)
want := 24.0
if got != want {
panic(fmt.Sprintf("Got %f, want %f", got, want))
}
// Re-enable when types2 bug is fixed (can't do T(1) with more than one
// type in the type list).
//got = fact(5)
//want = 120
//if want != got {
// panic(fmt.Sprintf("Want %d, got %d", want, got))
//}
}