[SR-16123] Non-escaping closure capturing inout wrongly assessed as escaping => error

[dabrahams]

Previous ID	SR-16123
Radar	None
Original Reporter	@dabrahams
Type	Bug
Status	Resolved
Resolution	Done

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug
Assignee	None
Priority	Medium

md5: 131508c8606cf9082245704a5b9fd7a9

Issue Description:

func f(a: inout Int) {
  let change: ()->Void = {
    a += 1
  }
  _ = change()
}

Diagnostics:

x.swift:2:26: error: escaping closure captures 'inout' parameter 'a'
  let change: ()->Void = {
                         ^
x.swift:1:8: note: parameter 'a' is declared 'inout'
func f(a: inout Int) {
       ^
x.swift:3:5: note: captured here
    a += 1
    ^

Yet somehow, the compiler knows that g doesn't escape in:

func call(_ f: ()->Void) {
  let g = f
  _ = g
}

func f(a: inout Int) {
  call {
    a += 1
  }
}

[benlangmuir]

@dabrahams should this be reopened? I see it was marked "resolved" on bugs.swift.org by another user within a couple hours of you filing it, and there is no comment indicating why.

[dabrahams]

🤷 Test it with the latest source I guess. I don't know why it would have been resolved.

[benlangmuir]

Still reproduces with latest compiler, reopening.