[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Dennis  changed:

   What|Removed |Added

   See Also||https://issues.dlang.org/sh
   ||ow_bug.cgi?id=22027

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Steven Schveighoffer  changed:

   What|Removed |Added

 Resolution|INVALID |FIXED

--- Comment #15 from Steven Schveighoffer  ---
Fixing the resolution, as the original bug was not invalid. If I have time,
I'll try to remember what this was about and open another enhancement request.

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Walter Bright  changed:

   What|Removed |Added

 Status|REOPENED|RESOLVED
 Resolution|--- |INVALID

--- Comment #14 from Walter Bright  ---
(In reply to Steven Schveighoffer from comment #12)
> ref inout should NOT be inferred as return. inout is a pattern match
> on the mutability of the parameters, it does not necessarily imply that it
> is part of the return type.

inout is deliberately inferred as return. It's the way the language currently
works. To change it please make an enhancement request, as such should be
discussed on its own merits.

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Mike Franklin  changed:

   What|Removed |Added

   See Also||https://issues.dlang.org/sh
   ||ow_bug.cgi?id=20156

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Mike Franklin  changed:

   What|Removed |Added

 CC||slavo5...@yahoo.com

--- Comment #13 from Mike Franklin  ---
Inferring `return` on `this` for anything marked with `inout` appears to be the
cause of issue 20149.

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Mike Franklin  changed:

   What|Removed |Added

   See Also||https://issues.dlang.org/sh
   ||ow_bug.cgi?id=20149

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Les De Ridder  changed:

   What|Removed |Added

 CC||dl...@lesderid.net

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Steven Schveighoffer  changed:

   What|Removed |Added

 Status|RESOLVED|REOPENED
 CC||schvei...@yahoo.com
 Resolution|FIXED   |---

--- Comment #12 from Steven Schveighoffer  ---
(In reply to Walter Bright from comment #4)
> It turns out that:
> 
>   struct String {
> inout(char)* mem2() inout scope @safe { return ptr; }
> char* ptr;
>   }
> 
> not issuing an error is actually correct, because a parameter that is `ref
> inout` is inferred to be `return`, and the `this` parameter for `mem2` is
> `ref inout`.


What? ref inout should NOT be inferred as return. inout is a pattern match on
the mutability of the parameters, it does not necessarily imply that it is part
of the return type.

This can be handy when trying avoid code duplication when the const/immutable
is nested under several indirections (including ref).

Reopening, the original problem is not fixed. The error case added tests for
compiling the functions, but doesn't test that the result of the inout function
is scope (it should be).

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Atila Neves  changed:

   What|Removed |Added

 CC||atila.ne...@gmail.com

--- Comment #11 from Atila Neves  ---
I don't understand how it's possible that making it `inout` is correct
inference. This allows for code that looks @safe but isn't. This really
shouldn't compile:

@safe:

const(int)* gInt;

void main() {
auto s = Struct();
gInt = s.ptr;  // ARGH!
}

struct Struct {

int* ints;

this(int size) {
import core.stdc.stdlib;
ints = () @trusted { return cast(int*) malloc(size); }();
}

~this() {
import core.stdc.stdlib;
() @trusted { free(ints); }();
}

scope inout(int)* ptr() inout {
return ints;
}
}



And yet it does. I guess I'll have to define 3 methods for mutable, const and
immutable if I want to not crash.

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

--- Comment #10 from Martin Nowak  ---
Thanks for investigating, so now it's reduced to the old problem that the scope
system does not allow to define entry points.
Of course in real life this is using malloc instead of GC'ed dup, but it's not
possible to contain the former.

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

--- Comment #9 from github-bugzi...@puremagic.com ---
Commits pushed to stable at https://github.com/dlang/dmd

https://github.com/dlang/dmd/commit/3f7544f355eacc0ad390a89b1bc07ca2dbcf835e
fix Issue 17927 - [scope]  parameter value can be escaped via return

https://github.com/dlang/dmd/commit/b46ac59c637723877b52b98ed50167e0f68aca5d
Merge pull request #7235 from WalterBright/fix17927

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

--- Comment #8 from github-bugzi...@puremagic.com ---
Commits pushed to master at https://github.com/dlang/dmd

https://github.com/dlang/dmd/commit/3f7544f355eacc0ad390a89b1bc07ca2dbcf835e
fix Issue 17927 - [scope]  parameter value can be escaped via return

https://github.com/dlang/dmd/commit/b46ac59c637723877b52b98ed50167e0f68aca5d
Merge pull request #7235 from WalterBright/fix17927

fix Issue 17927 - [scope]  'scope inout' parameter value can be escaped via
return

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

--- Comment #7 from Walter Bright  ---
Spec pull: https://github.com/dlang/dlang.org/pull/1914

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

--- Comment #6 from Walter Bright  ---
https://github.com/dlang/dmd/pull/7235

--

[Issue 17927] [scope] `scope inout` parameter value can be escaped via return

[d-bugmail--- via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=17927

Walter Bright  changed:

   What|Removed |Added

Summary|[scope] scope input return  |[scope] `scope inout`
   |value can be escaped|parameter value can be
   ||escaped via return

--