The main problem here is that getInt closure escapes when it can be folded into outer (even with call).

The issue here is we don't currently support inlining functions that contain closures. We'd first need to inline callFn into callInt to be able to inline getInt into outer.

Escape analysis is a red herring here. Escape analysis runs after inlining and doesn't affect inlining decisions.

/cc @danscales , who's working on making functions that contain closures inlinable

Yes, I will look at this bug, after I submit the base change that allows inlining of functions with closures.

Still reproduces on 1.17:

package main

import (
	"fmt"
	"testing"
)

func callInt(val int) int {
	getInt := func() int { return val }
	return callFn(getInt)
}

func callFn(getInt func() int) int {
	outer := func() int { return getInt() }
	return globalFunc(outer)
}

var globalFunc = func(f func() int) int {
	return f()
}

func main() {
	result := testing.Benchmark(Bench)
	fmt.Println("result.AllocsPerOp()", result.AllocsPerOp())
}

func Bench(b *testing.B) {
	for i := 0; i < b.N; i++ {
		callInt(i)
	}
}

Thank you, will take a look if any improvement is possible for 1.18.