[Issue 16218] Windows std.file.readImpl should be marked @system

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=16218

--- Comment #2 from anonymous4 <dfj1esp02 at sneakemail.com> ---
The "private @trusted" pattern is sort of a gray zone, it's used here for
safety inference. If readImpl was @system, all users will have to carefully
infer attributes, which is error-prone. That said, the huge trusted islands
make no sense indeed, whole readImpl should be a normal @trusted function, like
the posix variant. It takes a pointer, because tempCString returns a voldemort
type which is needlessly templated on the source range type.
BTW messing with trusted code is a rather cruel task for DSS.

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