[Issue 14618] can break immutable with inout and a delegate

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

https://issues.dlang.org/show_bug.cgi?id=14618

Iain Buclaw  changed:

   What|Removed |Added

   Priority|P1  |P3

--

[Issue 14618] can break immutable with inout and a delegate

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

https://issues.dlang.org/show_bug.cgi?id=14618

--- Comment #4 from ag0ae...@gmail.com ---
(In reply to Walter Bright from comment #2)
> If I prepend:
> 
>   @safe:
> 
> to the code:
[...]
>Error: cannot take address of local x in @safe function main

Compile with `-dip1000` and add `scope` to `f`'s parameter and it compiles
again:


@safe:

struct S
{
immutable(int)* p;
}

inout(int)* f(scope inout S s)
{
inout(int)* result;
auto dg = (inout(int)* p) {result = p;};
dg(s.p);
return result;
}

void main()
{
immutable int x = 42;
immutable int* p = 
assert(*p == 42); /* passes */
scope(exit) assert(*p == 42); /* fails */
int* m = f(S(p)); /* uh-oh */
*m = 13; /* writing over immutable *p */
}


The `scope` on the parameter is wrong here, of course, but the compiler doesn't
catch it.

--

[Issue 14618] can break immutable with inout and a delegate

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

https://issues.dlang.org/show_bug.cgi?id=14618

--- Comment #3 from Walter Bright  ---
The second example is still a bug.

--

[Issue 14618] can break immutable with inout and a delegate

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

https://issues.dlang.org/show_bug.cgi?id=14618

Walter Bright  changed:

   What|Removed |Added

 CC||bugzi...@digitalmars.com

--- Comment #2 from Walter Bright  ---
If I prepend:

  @safe:

to the code:

(In reply to ag0aep6g from comment #0)
> struct S
> {
> immutable(int)* p;
> }
> 
> inout(int)* f(inout S s)
> {
> inout(int)* result;
> auto dg = (inout(int)* p) {result = p;};
> dg(s.p);
> return result;
> }
> 
> void main()
> {
> immutable int x = 42;
> immutable int* p = 

   Error: cannot take address of local x in @safe function main

> assert(*p == 42); /* passes */
> scope(exit) assert(*p == 42); /* fails */
> int* m = f(S(p)); /* uh-oh */
> *m = 13; /* writing over immutable *p */
> }

--

[Issue 14618] can break immutable with inout and a delegate

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14618

ag0ae...@gmail.com changed:

   What|Removed |Added

   Keywords||safe

--- Comment #1 from ag0ae...@gmail.com ---
Also possible in @safe code:


struct S
{
immutable(int)* p;
}

inout(int)* f(inout S s) @safe
{
inout(int)* result;
auto dg = (inout(int)* p) {result = p;};
dg(s.p);
return result;
}

void main() @safe
{
immutable int* p = new int(42);
assert(*p == 42); /* passes */
scope(exit) assert(*p == 42); /* fails */
int* m = f(S(p)); /* uh-oh */
*m = 13; /* writing over immutable *p */
}


--