Re: variable _param_0 cannot be read at compile time

[learnfirst1 via Digitalmars-d-learn]

On Wednesday, 8 August 2018 at 13:13:42 UTC, Simen Kjærås wrote:
On Wednesday, 8 August 2018 at 12:57:43 UTC, learnfirst1 wrote:
Why this is a error ?
```
struct S {
        bool v;
        string x;
}

S* add(A...)(ref A a) {
        __gshared s = S(a);
        return &s;
}

void main(){
        auto p = add(true);
}
```

test.d(9): Error: variable _param_0 cannot be read at compile 
time

__gshared and static need to be initialized with a value known 
at compile-time. You're trying to give it a run-time value. You 
can set this after it's first created:

S* add(A...)(ref A a) {
    __gshared S s;
    s = S(a);
    return &s;
}

That's a little kludgy, but apparently that's how it be.

You also get another error message:
Error: function test.add!bool.add(ref bool _param_0) is not 
callable using argument types (bool)

That's because add takes its arguments by ref, and true is a 
literal that has no canonical address, and thus can't be passed 
by ref. You might consider using auto ref.

--
  Simen

is there a way to pass A a... as alias into template ? so the 
code can be just like this:

__gshared S s = S(&m, false);


the binary size is short since in this case the s is static build 
int. and run a bit fast.