[Issue 13781] Tuple assign should be @nogc

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13781

Kenji Hara <k.hara.pg at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|DMD                         |Phobos
           Hardware|x86                         |All
                 OS|Windows                     |All

--- Comment #2 from Kenji Hara <k.hara.pg at gmail.com> ---
(In reply to Peter Alexander from comment #1)
> Adding @nogc to Tuple.opAssign gives:
> 
> Error: @nogc function 'std.typecons.Tuple!(string,
> "s").Tuple.opAssign!(Tuple!(string, "s")).opAssign' cannot call non- at nogc
> function 'std.algorithm.swap!(Tuple!string).swap'
> 
> Adding @nogc to swap makes the code compile.
> 
> Both are templates, so @nogc should be inferred. Marking this as a DMD bug.

This is a little problem in Phobos code.

'swap' is used from the opAssign template function in Tuple, but swap checks
(hasElaborateAssign!T || !isAssignable!T) and it would see the signature of
T.opAssign. On mutual function calls, attributes are inferred as non- at nogc by
default. It's a design so this is not a compiler bug.

The correct fix is to mark std.algorithm.swap function as @nogc.

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