
-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

// Test of repeated use of wildcard in pattern.

// NB: multiple patterns would be required to handle variants such as
// s[:len(s)], s[x:len(s)], etc, since a wildcard can't match nothing at all.
// TODO(adonovan): support multiple templates in a single pass.

func before(s string) string { return s[:len(s)] }
func after(s string) string  { return s }

-- in/c1/c1.go --
package C1

import "strings"

func example() {
	x := "foo"
	println(x[:len(x)])

	// Match, but the transformation is not sound w.r.t. possible side effects.
	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 3))])

	// No match, since second use of wildcard doesn't match first.
	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 2))])

	// Recursive match demonstrating bottom-up rewrite:
	// only after the inner replacement occurs does the outer syntax match.
	println((x[:len(x)])[:len(x[:len(x)])])
	// -> (x[:len(x)])
	// -> x
}

-- out/c1/c1.go --
package C1

import "strings"

func example() {
	x := "foo"
	println(x)

	// Match, but the transformation is not sound w.r.t. possible side effects.
	println(strings.Repeat("*", 3))

	// No match, since second use of wildcard doesn't match first.
	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 2))])

	// Recursive match demonstrating bottom-up rewrite:
	// only after the inner replacement occurs does the outer syntax match.
	println(x)
	// -> (x[:len(x)])
	// -> x
}