7232 – Warning: statement is not reachable has no line number

When the following is compiled with -w or -wi, it will give a warning without a line number
----
bool addArticle()
{
 scope(failure) return false;
 return true;
}
----
Tested on dmd 2.057 on OS X 64 and Ubuntu 32.
$ dmd -w test.d
Warning: statement is not reachable

https://github.com/D-Programming-Language/dmd/pull/610
In addArticle function, dmd translates the body code like follows:
try {
 return true;
}
catch (Throwable __o) {
 return false;
 throw __o; // #1 rethrow catched exception object
}
The "statement is not reachable" warning is caused by line #1.
After my patch, the translation result would change like follows:
try {
 return true;
}
catch (Throwable __o) {
 return false; // this statement never fall through next.
 // so next unreachable rethrowing is implicitly removed.
}
Finally, original warning would never be generated.

Technical note:
Maybe, the original issue by Robert Clipsham is "unreachable scope(failure) should warn "statement is not reachable" _with line number_.
But today it is technically enhancement. Because:
1. Current D2 dmd does only check Exception throwing possibilities in flow analysis.
That means Throwable is not the target of the analysis. In above code,
 scope(failure) return false;
 return true; // (a)
dmd does not consider the statement (a) throws Throwable or not.
2. scope(failure) catches Throwable object and rethrow it. Therefore the scope(failure) statement is always analysed as *may be reachable*.
From the two reasons, current dmd cannot detect that the `scope(failure) return false;` is not reachable.

Posted bug 7240 as an enhancement.

https://github.com/D-Programming-Language/dmd/commit/458065293bd4cf990fb99bcd01fc294e7df21c17
https://github.com/D-Programming-Language/dmd/commit/986404479ea9eac7a9caa32be1f92c22a8aee38a 

There's a missing line number with -w here also (recent dmd):
import std.stdio;
void f()
{
 throw new Exception("msg");
 scope(exit) write("5");
 scope(success) write("6");
}