https://issues.dlang.org/show_bug.cgi?id=17138

Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
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                 CC|                            |bugzilla@digitalmars.com

--- Comment #1 from Walter Bright <bugzilla@digitalmars.com> ---
What does the declaration of someObject look like?

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https://issues.dlang.org/show_bug.cgi?id=17138

--- Comment #2 from Eyal <eyal@weka.io> ---
struct Object {
   auto acquired() {
     struct Acquired {
         Object obj;
         this(Object* obj) { this.obj = obj; obj.acquire(); }
         ~this() { obj.release(); }
     }
     return Acquired(&this);
   }
   ...
}

Resource someObject;
with(someObject.acquired()) { // <-- makes sense
  ..
}

Resource someObject;
with(someObject) { // Oops! Accidental senseless 'with' statement
  ..
}

The latter can be detected as senseless, since it doesn't affect the code in any way.

If dropping the with() statement (and keeping its body instead) would result in
the exact same semantics -- warn about superfluous 'with' statement.

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https://issues.dlang.org/show_bug.cgi?id=17138

--- Comment #3 from Walter Bright <bugzilla@digitalmars.com> ---
Are you suggesting:

---
struct S {
    int field;
}

void foo(S s) {
    with (s)      // no error
        ++field;

    with (s)      // error
        ++s.field;
}
---

?

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https://issues.dlang.org/show_bug.cgi?id=17138

--- Comment #4 from Eyal <eyal@weka.io> ---
Yes, that would be great.

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https://issues.dlang.org/show_bug.cgi?id=17138

--- Comment #5 from Eyal <eyal@weka.io> ---
Another case that is beneficial and should not be an error:

If the expression results in an object that scopes over the block and has a destructor.

Example:

with(someMutex.acquired) {

  // No use of any fields from the MutexAcquired object

} // dtor of MutexAcquired called here, releasing the mutex

So here you'd want no error either.

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https://issues.dlang.org/show_bug.cgi?id=17138

Iain Buclaw <ibuclaw@gdcproject.org> changed:

           What    |Removed                     |Added
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           Priority|P1                          |P4

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