[Issue 14125] @trusted nested helper functions in std.file

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14125

John Colvin <john.loughran.colvin at gmail.com> changed:

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--- Comment #75 from John Colvin <john.loughran.colvin at gmail.com> ---
Walter and Andrei are completely right here.

If you can't factor out the @system code to a function providing a truly safe
interface (marked with @trusted), then the code clearly depends on its
surrounding context to make it safe. So *all* of that code needs to be manually
verified with the same scrutiny, together with the core bit that actually
appeared to be @system.

It becoming a maintenance nightmare is just unveiling the true difficulty of
safely using @system code, as opposed to papering over it.

It might become good practice in robust @trusted code to add static asserts to
ensure that changes to @system (explicit or inferred) further down the call
tree aren't accidentally missed. static assert(isTrusted!func) or similar.

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