On 2/21/15 9:27 PM, Peter Alexander wrote:
On Sunday, 22 February 2015 at 01:24:09 UTC, Almighty Bob wrote:
a += b; // Compiles with no ERROR!
Please tell me that's a bug?
Not a bug. From spec:
http://dlang.org/expression.html#AssignExpression
Assignment operator expressions, such as:
a op= b
are semantically equivalent to:
a = cast(typeof(a))(a op b)
Seems questionable to me. Anyone know the rationale? If a = b; is
disallowed, I don't see why a += b; should be more acceptable.
I think the docs are misleading.
For example, this doesn't work:
int a;
int *b = &a;
a += b;
Error: incompatible types for ((a) += (b)): 'int' and 'int*'
But this does:
a = cast(typeof(a))(a + b);
I think it only works if it's a numeric narrowing conversion, but I
don't know for sure. I would be happy if this behavior changed as the OP
expected. But I'm glad there isn't exactly an unfettered implicit cast
in every op= operation.
Does anyone know the true rules for this, and can they please file an PR
on the docs?
-Steve
