Does the compiler automatically pass values by reference if possible with `in` parameters in higher level of optimization flags? I would normally use `in ref` but sometimes it's not compatible with different types.

On Wednesday, 25 December 2019 at 01:24:52 UTC, Adnan wrote:
> Does the compiler automatically pass values by reference if possible with `in` parameters in higher level of optimization flags? I would normally use `in ref` but sometimes it's not compatible with different types.

No. "in" is short for "const scope" (https://dlang.org/spec/function.html#param-storage). The only mechanism D has for expressing "pass this argument by ref if possible, and by value otherwise" is "auto ref" (https://dlang.org/spec/function.html#auto-ref-functions), which requires your function to be templated.