[Issue 22539] New: [dip1000] slicing of returned ref scope static array should not be allowed
d-bugmail at puremagic.com
d-bugmail at puremagic.com
Tue Nov 23 19:38:16 UTC 2021
https://issues.dlang.org/show_bug.cgi?id=22539
Issue ID: 22539
Summary: [dip1000] slicing of returned ref scope static array
should not be allowed
Product: D
Version: D2
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P1
Component: dmd
Assignee: nobody at puremagic.com
Reporter: dkorpel at live.nl
Because there is no transitive scope, taking the address of a scope variable is
not allowed. There are 4 cases:
- ref param &pointer: rejected with `checkAddresVar`
- ref param slice[]: rejected with `checkAddresVar`
- ref return &pointer: too restrictive (issue 22519)
- ref return slice[]: too lenient (this issue)
This allows you to escape scope pointers:
```
// REQUIRED_ARGS -preview=dip1000
@safe:
ref int*[1] identity(ref return scope int*[1] x)
{
return x;
}
int* escape()
{
int stackVar = 0xFF;
scope int*[1] x = [&stackVar];
int*[] y = identity(x)[];
return y[0];
}
void main()
{
int* dangling = escape();
}
```
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