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go/test/escape_calls.go
Matthew Dempsky e99e9a6e01 [dev.typeparams] cmd/compile: simplify ~r/~b naming
The compiler renames anonymous and blank result parameters to ~rN or
~bN, but the current semantics for computing N are rather annoying and
difficult to reproduce cleanly. They also lead to difficult to read
escape analysis results in tests.

This CL changes N to always be calculated as the parameter's index
within the function's result parameter tuple. E.g., if a function has
a single result, it will now always be named "~r0".

The normative change to this CL is fairly simple, but it requires
updating a lot of test expectations.

Change-Id: I58a3c94de00cb822cb94efe52d115531193c993c
Reviewed-on: https://go-review.googlesource.com/c/go/+/323010
Trust: Matthew Dempsky <mdempsky@google.com>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>
2021-05-26 23:50:32 +00:00

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Go

// errorcheck -0 -m -l
// Copyright 2015 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.
// Test escape analysis for function parameters.
// In this test almost everything is BAD except the simplest cases
// where input directly flows to output.
package foo
func f(buf []byte) []byte { // ERROR "leaking param: buf to result ~r0 level=0$"
return buf
}
func g(*byte) string
func h(e int) {
var x [32]byte // ERROR "moved to heap: x$"
g(&f(x[:])[0])
}
type Node struct {
s string
left, right *Node
}
func walk(np **Node) int { // ERROR "leaking param content: np"
n := *np
w := len(n.s)
if n == nil {
return 0
}
wl := walk(&n.left)
wr := walk(&n.right)
if wl < wr {
n.left, n.right = n.right, n.left // ERROR "ignoring self-assignment"
wl, wr = wr, wl
}
*np = n
return w + wl + wr
}
// Test for bug where func var f used prototype's escape analysis results.
func prototype(xyz []string) {} // ERROR "xyz does not escape"
func bar() {
var got [][]string
f := prototype
f = func(ss []string) { got = append(got, ss) } // ERROR "leaking param: ss" "func literal does not escape"
s := "string"
f([]string{s}) // ERROR "\[\]string{...} escapes to heap"
}