On Friday, 1 April 2016 at 01:21:32 UTC, Walter Bright wrote:
On 3/16/2016 4:18 AM, Johan Engelen wrote:
I've found discussions, but not an actual "recommended"
solution for the
problem of "statement is not reachable" warnings in templates
with early
returns, e.g.:
```
bool nobool(T...)() {
foreach (i, U; T) {
static if (is(U == bool)) {
return false;
}
}
return true; // emits "Warning: statement is not
reachable"
}
bool nobool(T...)() {
bool result = true;
foreach (i, U; T) {
static if (is(U == bool)) {
result = false;
break;
}
else
{
...
}
}
return result; // emits "Warning: statement is not
reachable"
}
As you can see from my first post, that is the solution I used
first (without the "break;" addition), but it works until...
Note that the optimizer will remove the dead loads.
... until someone adds a (imho useful) diagnostic of dead
stores/loads. :-)
In that case, I guess inverting all bools and then inverting the
return value at the end will work (using default initialization
of result); but this is not possible in a slightly more
complicated case with non-bool return types.
In another piece of code, the return type is a struct with an
immutable member. That's when I gave up on working around the
warning and just disabled it.
Simplified, something like this:
struct IMM {
immutable bool result;
}
IMM immut(T...)() {
IMM retval = IMM(true);
foreach (i, U; T) {
static if (is(U == bool)) {
retval = IMM(false); // "Error: cannot modify
struct retval IMM with immutable member".
}
}
return retval;
}
