Entt: resource_cache move ctor

[NullBy7e]

Hey,

With the latest src of entt (master) I'm getting an error in resource/cache.hpp on line 39 related to the default move constructor that's defined there:

resource_cache(resource_cache &&) ENTT_NOEXCEPT = default;

`1>entt/resource/cache.hpp(39): error : exception specification of explicitly defaulted move constructor does not match the calculated one
1>./managers/texture_manager.hpp(47): note: in instantiation of template class 'entt::resource_cache<sf::Texture>' requested here`

This is the line in texture_manager.hpp:

using texture_cache = entt::resource_cache<sf::Texture>;
texture_cache textures;

The issue no longer appears when I comment out the move ctor but I'm sure that it's there for a reason?

I'm compilling my project on x64 with CLANG/LLVM.

[skypjack]

Uhm... Have you exceptions turned on? Try to remove the ENTT_NOEXCEPT part only and let me know what happens, please.

[NullBy7e]

Uhm... Have you exceptions turned on? Try to remove the ENTT_NOEXCEPT part only and let me know what happens, please.

Removed ENTT_NOEXCEPT and it compiles succesfully.

[NullBy7e]

Seems to be related to CLANG, it compiles with ENTT_NOEXCEPT using MSVC (Visual Studio 2017 (v141) toolset)

[skypjack]

What version of clang?

[NullBy7e]

What version of clang?

Version 8.0.0
http://releases.llvm.org/8.0.0/tools/clang/docs/index.html

[skypjack]

I think clang is right in this case. The exception specification from the std::unordered_map is incompatible with that of the cache actually.
Good point. :+1:

[NullBy7e]

I think clang is right in this case. The exception specification from the std::unordered_map is incompatible with that of the cache actually.
Good point. 👍

Is that something that you can address by changing the code or should I just keep the NOEXCEPT commented out?

[ColinH]

The problem is that the cache marks its move-c'tor as noexcept. Its a problem because it invokes the move-c'tor from std::unordered_map which is however _not_ marked noexcept. The compiler is complaining about this discrepancy (don't want to call a non-noexcept-marked, i.e. potentially throwing, function from a noexcept-marked one). Once the cache's move-c'tor is no longer noexcept the warning or error should go away, so just a small change to EnTT.

[skypjack]

Yep, confirmed, a change to EnTT is required.
You've to wait until I'm back home, then I'll do it directly upstream.
I'm marking this as a bug to give it higher priority. :+1:

[NullBy7e]

Great! No rush, I've adjusted it locally in the src for the time being.

Outlook voor Android downloadenhttps://aka.ms/ghei36

---

From: Michele Caini [e-mail]
Sent: Monday, April 29, 2019 12:01:41 AM
To: skypjack/entt
Cc: NullBy7e; Author
Subject: Re: [skypjack/entt] resource_cache move ctor (#233)

Yep, confirmed, a change to EnTT is required.
You've to wait until I'm back home, then I'll do it directly upstream.

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