Issue with C++20 because of struct concept

[sxh07241]

concept/requires are new keyword in c++20.
in benchmark_function.h++ it would help to replace struct concept with something like struct concept_layer or which ever makes sense.

[sehe]

Is there a particular problem you're running into? I use Nonius in c++23/c++26 code without ever noticing an issue.

[sxh07241]

Thanks for looking into this. It doesn't compile in ubuntu 20.04 when using gcc 10.5 and selecting C++20. I patched the file with a "struct conceptBase" and I was able to compile. Maybe this is an issue with gcc 10.5 that I'm using in this project. I don't have an issue in C++17 but I need to prepare for a move to ubuntu 24.04. I thought avoiding keyword from the language would be a good idea.

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________________________________ From: sehe ***@***.***> Sent: Thursday, September 18, 2025 10:45 AM To: libnonius/nonius ***@***.***> Cc: Stephane Harnois ***@***.***>; Author ***@***.***> Subject: [EXTERNAL] Re: [libnonius/nonius] Issue with C++20 because of struct concept (Issue #115) External Message:Use caution before opening links or attachments [https://avatars.githubusercontent.com/u/324097?s=20&v=4]sehe left a comment (libnonius/nonius#115)<https://urldefense.com/v3/__https://github.com/libnonius/nonius/issues/115*issuecomment-3307892739__;Iw!!A4SSUj6ze24l42k!d-tsR6iEzIYz_GcZBNZhMLEe3eqOGUcYQDbYoqd6YGCitDdIS_KmBoqYSEPW7xyqRGwHd4Us9d598XttCfDf-dbmiM4wGSpXlw$> Is there a particular problem you're running into? I use Nonius in c++23/c++26 code without ever noticing an issue. — Reply to this email directly, view it on GitHub<https://urldefense.com/v3/__https://github.com/libnonius/nonius/issues/115*issuecomment-3307892739__;Iw!!A4SSUj6ze24l42k!d-tsR6iEzIYz_GcZBNZhMLEe3eqOGUcYQDbYoqd6YGCitDdIS_KmBoqYSEPW7xyqRGwHd4Us9d598XttCfDf-dbmiM4wGSpXlw$>, or unsubscribe<https://urldefense.com/v3/__https://github.com/notifications/unsubscribe-auth/BEZZMKAG6BCYBM2EGK4GV233TLAPVAVCNFSM6AAAAACGY5ZLXSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGMBXHA4TENZTHE__;!!A4SSUj6ze24l42k!d-tsR6iEzIYz_GcZBNZhMLEe3eqOGUcYQDbYoqd6YGCitDdIS_KmBoqYSEPW7xyqRGwHd4Us9d598XttCfDf-dbmiM4pufTMaQ$>. You are receiving this because you authored the thread.Message ID: ***@***.***> ********************************************************************** DISCLAIMER: Privileged and/or Confidential information may be contained in this message. If you are not the addressee of this message, you may not copy, use or deliver this message to anyone. In such event, you should destroy the message and kindly notify the sender by reply e-mail. It is understood that opinions or conclusions that do not relate to the official business of the company are neither given nor endorsed by the company. Thank You.

[rmartinho]

To be completely honest, I consider this project abandonware: I don't use nonius, I no longer work with C++, I don't even work as a programmer anymore. Maybe I should find someone to take over as maintainer.

This seems simple amd serious enough that I'll look into it, though.

[sehe]

To be even more honest, I think it's a non-issue, seemingly arising from the use of GCC 10.5 (this release series is no longer supported).

With "regular" GCC versions, there doesn't seem to be an issue. I recently posted a stackoverflow answer using Nonius:

https://coliru.stacked-crooked.com/a/89945d13ee109b2f (c++20)

which also works fine with c++23

https://coliru.stacked-crooked.com/a/0055046afc58724b (c++23)

or even c++26

https://coliru.stacked-crooked.com/a/568b3463ebeb8863

EDIT/UPDATE

I was able to check with gcc 10.5.0 and the same versions of boost/nonius and (despite a bunch of deprecation warnings that were apparently spurious), it still worked just fine

[sxh07241]

Np, I can patch locally until we move up to a newer gcc.

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________________________________ From: sehe ***@***.***> Sent: Saturday, September 20, 2025 5:35 PM To: libnonius/nonius ***@***.***> Cc: Stephane Harnois ***@***.***>; Author ***@***.***> Subject: [EXTERNAL] Re: [libnonius/nonius] Issue with C++20 because of struct concept (Issue #115) External Message:Use caution before opening links or attachments [https://avatars.githubusercontent.com/u/324097?s=20&v=4]sehe left a comment (libnonius/nonius#115)<https://urldefense.com/v3/__https://github.com/libnonius/nonius/issues/115*issuecomment-3315276494__;Iw!!A4SSUj6ze24l42k!ZXP0fG6ChBiVjcnL_LEqZGJo89vtp7JDinNepP7DICuCPSY5dFX-7xDKTlCHfwhsFn2i2itw49KQXtaECZTU6GfTzTENVqKgjQ$> To be even more honest, I think it's a non-issue, seemingly arising from the use of GCC 10.5 (this release series is no longer supported<https://urldefense.com/v3/__https://gcc.gnu.org/gcc-10/__;!!A4SSUj6ze24l42k!ZXP0fG6ChBiVjcnL_LEqZGJo89vtp7JDinNepP7DICuCPSY5dFX-7xDKTlCHfwhsFn2i2itw49KQXtaECZTU6GfTzTHUDuICNQ$>). With "regular" GCC versions, there doesn't seem to be an issue. I recently posted a stackoverflow answer<https://urldefense.com/v3/__https://stackoverflow.com/a/79752712/85371__;!!A4SSUj6ze24l42k!ZXP0fG6ChBiVjcnL_LEqZGJo89vtp7JDinNepP7DICuCPSY5dFX-7xDKTlCHfwhsFn2i2itw49KQXtaECZTU6GfTzTFx4ZRtqw$> using Nonius: https://coliru.stacked-crooked.com/a/89945d13ee109b2f<https://urldefense.com/v3/__https://coliru.stacked-crooked.com/a/89945d13ee109b2f__;!!A4SSUj6ze24l42k!ZXP0fG6ChBiVjcnL_LEqZGJo89vtp7JDinNepP7DICuCPSY5dFX-7xDKTlCHfwhsFn2i2itw49KQXtaECZTU6GfTzTEMZ9nExw$> (c++20) which also works fine with c++23 https://coliru.stacked-crooked.com/a/0055046afc58724b<https://urldefense.com/v3/__https://coliru.stacked-crooked.com/a/0055046afc58724b__;!!A4SSUj6ze24l42k!ZXP0fG6ChBiVjcnL_LEqZGJo89vtp7JDinNepP7DICuCPSY5dFX-7xDKTlCHfwhsFn2i2itw49KQXtaECZTU6GfTzTEt6j8llw$> (c++23) or even c++26 https://coliru.stacked-crooked.com/a/568b3463ebeb8863<https://urldefense.com/v3/__https://coliru.stacked-crooked.com/a/568b3463ebeb8863__;!!A4SSUj6ze24l42k!ZXP0fG6ChBiVjcnL_LEqZGJo89vtp7JDinNepP7DICuCPSY5dFX-7xDKTlCHfwhsFn2i2itw49KQXtaECZTU6GfTzTG1Iw4lKQ$> — Reply to this email directly, view it on GitHub<https://urldefense.com/v3/__https://github.com/libnonius/nonius/issues/115*issuecomment-3315276494__;Iw!!A4SSUj6ze24l42k!ZXP0fG6ChBiVjcnL_LEqZGJo89vtp7JDinNepP7DICuCPSY5dFX-7xDKTlCHfwhsFn2i2itw49KQXtaECZTU6GfTzTENVqKgjQ$>, or unsubscribe<https://urldefense.com/v3/__https://github.com/notifications/unsubscribe-auth/BEZZMKHOUSSHR2B5AGFO4ZD3TXCD5AVCNFSM6AAAAACGY5ZLXSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGMJVGI3TMNBZGQ__;!!A4SSUj6ze24l42k!ZXP0fG6ChBiVjcnL_LEqZGJo89vtp7JDinNepP7DICuCPSY5dFX-7xDKTlCHfwhsFn2i2itw49KQXtaECZTU6GfTzTGMofRfaw$>. You are receiving this because you authored the thread.Message ID: ***@***.***> ********************************************************************** DISCLAIMER: Privileged and/or Confidential information may be contained in this message. If you are not the addressee of this message, you may not copy, use or deliver this message to anyone. In such event, you should destroy the message and kindly notify the sender by reply e-mail. It is understood that opinions or conclusions that do not relate to the official business of the company are neither given nor endorsed by the company. Thank You.