[Issue 15166] [REG2.069-devel] spurious statement not reachable warning in static foreach loop

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15166

Steven Schveighoffer  changed:

   What|Removed |Added

 CC||schvei...@yahoo.com

--- Comment #6 from Steven Schveighoffer  ---
(In reply to Martin Nowak from comment #4)
> A workaround is to use a variable.

I think this may be the right answer.

It boils down to this:

static if(someCondition) return false;
return true;

Which you would normally write with else, but it's not so simple in this case,
because the "else" would be part of the loop.

I'm curious why the return short-circuits the loop. In other words, why aren't
all the "return false" statements besides the first one flagged for
unreachability? Is it because the compiler stops generating the statements? I
mean, if you rewrote as a bunch of static ifs, then wouldn't you have the same
problem?

Another possible answer is to do this:

private bool compare(alias Group1, alias Group2)()
{
foreach (index, element; Group!(Group1.expand, void).expand)
{
static if(index == Group1.expand.length)
return true;
else static if (!is(Group1.expand[index] == Group2.expand[index]))
return false;
}
}

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[Issue 15166] [REG2.069-devel] spurious statement not reachable warning in static foreach loop

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15166

Martin Nowak  changed:

   What|Removed |Added

 Status|NEW |RESOLVED
 Resolution|--- |DUPLICATE

--- Comment #5 from Martin Nowak  ---


*** This issue has been marked as a duplicate of issue 14835 ***

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[Issue 15166] [REG2.069-devel] spurious statement not reachable warning in static foreach loop

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15166

--- Comment #4 from Martin Nowak  ---
A workaround is to use a variable.

bool res = true;
foreach (index, element; Group1.expand)
{
static if (!is(Group1.expand[index] == Group2.expand[index]))
{
res = false;
break;
}
}
return res;

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[Issue 15166] [REG2.069-devel] spurious statement not reachable warning in static foreach loop

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15166

--- Comment #3 from Martin Nowak  ---
I think something along this line could work.

override void visit(ConditionalStatement s)
{
if (s.condition.include(null, null))
{
result = s.ifbody.blockExit(func, mustNotThrow);
// mark as conditional fallthru, see Bugzilla 14835
if (!s.elsebody) result |= BEconditional;
}
else if (s.elsebody)
result = s.elsebody.blockExit(func, mustNotThrow);
else
result = BEfallthru;
}

if (!(result & (BEfallthru | BEconditional)) && !s.comeFrom())
{
if (s.blockExit(func, mustNotThrow) != BEhalt && s.hasCode())
s.warning("statement is not reachable");
}

But for this to work ConditionalStatement must no longer be flattened before
computing blockExit, thus making this change very big (and somewhat risky).

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[Issue 15166] [REG2.069-devel] spurious statement not reachable warning in static foreach loop

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15166

--- Comment #2 from Martin Nowak  ---
This is as annoying as go's stupid "unused variable" warning, at least during
development.

> I'm not sure how we can "fix" this and issue 14835.

I guess the fix would be to mark those returns as dependent on the template
types and not account for them when computing not reachable statements, but
that sounds like quite a difficult change.
I guess we might fix this in vibe.d but it might break a lot more code.

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[Issue 15166] [REG2.069-devel] spurious statement not reachable warning in static foreach loop

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15166

Kenji Hara  changed:

   What|Removed |Added

Summary|[Ref 2.069-devel] spurious  |[REG2.069-devel] spurious
   |statement not reachable |statement not reachable
   |warning in static foreach   |warning in static foreach
   |loop|loop

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