Changing the name of that identifier is easy so maybe it’s possible to warn programmers about it and just introduce it if it’s going to help us.

A bit of uncomfortable phase, sure, but maybe it’s better that way for everyone.

Cheers, Filip

> Wiadomość napisana przez Sebastian Wittmeier via Std-Proposals <std-proposals_at_[hidden]> w dniu 19 mar 2025, o godz. 09:26:
>
> 
> It would, but with its own cost.
>
> All current programs using fn as an identifier would malfunction.
>
>
>
> There are far less common and longer potential keywords, which have been rejected for that reason.
>
>
> -----Ursprüngliche Nachricht-----
> Von: Filip <fph2137_at_[hidden]>
> Gesendet: Mi 19.03.2025 09:22
> Betreff: Re: [std-proposals] Proposal: Making The auto Keyword Optional in Trailing Return Types
> An: std-proposals_at_[hidden];
> CC: Sebastian Wittmeier <wittmeier_at_[hidden]>; std-proposals_at_[hidden];
> Just a thought but wouldn’t introducing keyword ‘fn’
> Simplify compilation?
> It would be easier for the compiler to know if what is being written is specifically a function or a variable.
>
> Cheers, Filip
>
>>> Wiadomość napisana przez Sebastian Wittmeier via Std-Proposals <std-proposals_at_[hidden]> w dniu 19 mar 2025, o godz. 07:02:
>>>
>> 
>> See
>>
>> https://www.reddit.com/r/cpp/comments/cn863t/why_is_auto_required_when_using_a_trailing_return/?rdt=44901
>>
>> with
>>
>> https://godbolt.org/z/2jXUG9
>>
>>
>> -----Ursprüngliche Nachricht-----
>> Von: Fady al Dhaim via Std-Proposals <std-proposals_at_[hidden]>
>> Gesendet: Mi 19.03.2025 02:57
>> Betreff: [std-proposals] Proposal: Making The auto Keyword Optional in Trailing Return Types
>> An: std-proposals_at_[hidden];
>> CC: Fady al Dhaim <fadyaldhaim_at_[hidden]>;
>> Hello,
>>
>> I’d like to propose a small but meaningful change to C++: making auto optional in trailing return types.
>>
>> 1. Motivation
>> Currently, auto is required in functions that use trailing return types:
>>
>> auto func() -> int; // Required
>> However, this requirement is redundant and misleading because:
>>
>> The return type is explicitly specified (int), so auto adds no value.
>> auto implies type deduction, but no deduction is happening here.
>> A more natural syntax would allow:
>>
>> func() -> int; // More intuitive Right?
>
> Not only does this improve readability and consistency with standard function declarations, but it also aligns well with Software Engineering Structural Diagrams, such as UML Class Diagrams and Object Diagrams.
>
>
>
> In UML Class Diagrams, method return types are typically represented after the function name, similar to how trailing return types work in C++. Allowing func() -> int; without auto makes the C++ syntax closer to UML representations, enhancing clarity and traceability between a codebase and its corresponding UML models.
>
> 2. Why This Won’t Break Existing Code
> This proposal is backward-compatible because:
>
> auto is already optional in normal return types:
>
> int func();
> This change is purely syntactic—it does not affect semantics.
>
> Existing code using auto remains fully valid.
> auto func() -> int; // Remains valid
> auto func() -> decltype(some_expression); // Also valid
>
> Thus, this proposal only removes an unnecessary restriction without introducing breaking changes.
>
> 3. Proposed Change
> Modify the C++ grammar so that functions using trailing return types no longer require auto.
> This would allow:
>
> Current (C++ Standard Today)
> auto func() -> int; // Required
> Proposed (New Syntax Allowance)
> func() -> int; // Allowed
> This makes the syntax more consistent with regular function declarations.
>
> 4. Next Steps
> Would this be a reasonable proposal for a future C++ standard update?
> I’d love to hear your thoughts and suggestions on how this could be refined further.
>
> Best regards,
> Fady al Dhaim
>
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