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Code:
constexpr std::string cs{ "hello" };
GCC is happy with it but Visual C++ does not accept the constexpr string with error:
error C2131: expression did not evaluate to a constant
std::string is a literal class since C++20. Why can't Visual C++ compile the above statement?
I am using VS2019 version 16.11.36. I have specified the C++ language standard to be C++20.
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It does seem to be an anomaly that other recent compilers handle. I suggest that you report it using VS's "Report a Problem" facility. Post a link to your bug report back here so that we can follow it.
The link of "Report a Problem" is here: https://developercommunity.visualstudio.com/t/VC-does-not-follow-the-convention-of-str/10755072
The link of "Report a Problem" is here: https://developercommunity.visualstudio.com/t/Visual-C-does-not-accept-constexpr-str/10755075
The comment containing the link does not show. What's the matter?
The link cannot be posted. It says: "This answer has been deleted due to a violation of our Code of Conduct. The answer was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information." What's the matter?
Visual Studio 2022 version 17.4 is the first version of MSVC that supports constexpr string. It's time to say goodbye to VS2019 and upgrade to VS2022. This ticket can be closed now (although I still hope VS2019 can support constexpr string in its next version released soon).
Hmm, while I can reproduce what you say in a console project with the latest VS (Version 17.12.0 Preview 2.1), a simple test on compiler explorer works as the other compilers do. Presumably some other command line option present in the console project is having an influence.
Oh, a DEBUG build exhibits this problem, while a RELEASE build doesn't.
Can you check this and if you agree, modify your bug report to mention this.
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Hi, @zzzhhh
Regarding the debug mode not being able to compile, it is by design:
https://github.com/microsoft/STL/issues/4427
Best regards,
Minxin Yu
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