On Sunday, 25 February 2018 at 04:47:47 UTC, Nicholas Wilson
wrote:
On Sunday, 25 February 2018 at 04:06:43 UTC, Meta wrote:
I just filed this bug:
https://issues.dlang.org/show_bug.cgi?id=18520
Not only does the following code compile and link
successfully, it prints 0 three times when ran:
alias f = (int n) => 0;
alias f = (char c) => 'a';
alias f = (bool b) => false;
void main()
{
import std.stdio;
writeln(f(int.init)); //Prints 0
writeln(f(char.init)); //Prints 0
writeln(f(bool.init)); //Prints 0
}
[...]
4. Is there any different semantically or mechanically between
my first and second examples?
Type promotions to int maybe?
Have you tried casting them?
void main()
{
import std.stdio;
writeln(f(cast(int)int.init));
writeln(f(cast(char)char.init));
writeln(f(cast(bool)bool.init));
}
Ah, I tried changing it to the following:
struct NoPromote {}
alias f = (int n) => 0;
alias f = (char c) => 'a';
alias f = (NoPromote np) => NoPromote();
void main()
{
import std.stdio;
writeln(f(int.init)); //Prints 0
writeln(f(char.init)); //Prints 0
writeln(f(NoPromote.init)); //Prints 0
}
And I get "Error: function literal __lambda5 (int n) is not
callable using argument types (NoPromote)". It was already
apparent from the fact that the program printed 0 each time, but
this confirms that the first function literal is the only one
that _really_ gets aliased to f. Actually, this is unnecessary,
because if I just change the order and move the bool function up
to be the first, I get "Error: function literal __lambda4 (bool
b) is not callable using argument types (char)".
Did I mention how much I hate the fact that char and bool
implicitly convert to int?
