https://issues.dlang.org/show_bug.cgi?id=16201

Mathias Lang <mathias.lang@sociomantic.com> changed:

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                 CC|                            |mathias.lang@sociomantic.co
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--- Comment #1 from Mathias Lang <mathias.lang@sociomantic.com> ---
I suppose this proposal only applies to function body, and not other places where `static if` might appear ?

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https://issues.dlang.org/show_bug.cgi?id=16201

--- Comment #2 from Andrei Alexandrescu <andrei@erdani.com> ---
(In reply to Mathias Lang from comment #1)
> I suppose this proposal only applies to function body, and not other places where `static if` might appear ?

Correct, sorry for being unclear.

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https://issues.dlang.org/show_bug.cgi?id=16201

Steven Schveighoffer <schveiguy@yahoo.com> changed:

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                 CC|                            |schveiguy@yahoo.com

--- Comment #3 from Steven Schveighoffer <schveiguy@yahoo.com> ---
I think this is a dup of issue 14835.

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https://issues.dlang.org/show_bug.cgi?id=16201

--- Comment #4 from Andrei Alexandrescu <andrei@erdani.com> ---
Sorry for being unclear. It's a superset, not a dupe of 14835. Consider:

void fun(T)(T obj)
{
    static if (!hasMember(T, "gun")) throw new Exception("No gun");
    obj.gun;
}

This code should just work.

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https://issues.dlang.org/show_bug.cgi?id=16201

--- Comment #5 from Steven Schveighoffer <schveiguy@yahoo.com> ---
Thanks for the example. That makes things much clearer.

Essentially, the else code should parse as valid D, but doesn't need to be semantically analyzed once it's determined that the branch will never execute (or at least the error is gagged once it's determined).

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https://issues.dlang.org/show_bug.cgi?id=16201

Steven Schveighoffer <schveiguy@yahoo.com> changed:

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           See Also|                            |https://issues.dlang.org/sh
                   |                            |ow_bug.cgi?id=14835

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https://issues.dlang.org/show_bug.cgi?id=16201

--- Comment #6 from Mathias Lang <mathias.lang@sociomantic.com> ---
Should it only work on `static if` level ?

E.g. if you have:

```
void fun(T)(T obj)
{
    throw new Exception("No gun");
    obj.gun;
}
```

Should it have the same behaviour ?
If not, that should be fixable at the same time as issue 14835 (and has the
same prerequisites).

However, it's not trivial to implement either, e.g. consider the following code:

```
void fun(T)(T obj)
{
    static if (!hasMember(T, "gun")) {
      if (bar)
         goto Label;
      throw new Exception("No gun");
    }
    // This would not be compiled in after the change, resulting in an
    // "undefined label 'Label'" error.
    Label: myFunc();
}
```

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https://issues.dlang.org/show_bug.cgi?id=16201

--- Comment #7 from Steven Schveighoffer <schveiguy@yahoo.com> ---
One thing that comes to mind on this -- successful compilation will DEPEND on the ability to determine whether a branch escapes or not.

The goto is one thing.

What about a function that always throws and is inlined? (brought up by ketmar in the forum discussion). A clever enough compiler can compile stuff that other compilers do not. In essence the language needs to be very clear to what level the implementation must go in order to prove it shouldn't look at the other pieces.

With the unreachable statement warning, it's just a warning. One can still compile without making it an error (and the warning is optional of course). For this, it's not possible to make it a warning -- the code that should be ignored won't compile.

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https://issues.dlang.org/show_bug.cgi?id=16201

Les De Ridder <dlang@lesderid.net> changed:

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                 CC|                            |dlang@lesderid.net

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https://issues.dlang.org/show_bug.cgi?id=16201

Iain Buclaw <ibuclaw@gdcproject.org> changed:

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           Priority|P1                          |P4

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