In this update, we continue the tradition of bucketing bugs into helpful categories for you all to filter through along with even more<\/em> notes from the compiler team as to what, exactly, was fixed. This blog is also complemented by the recent Pure Virtual C++<\/a> pre-conference talk by RanDair Porter; so please check out RanDair’s talk, “MSVC C++23 Conformance”<\/a>, if you have not already to get a better view of MSVC’s conformance status for Visual Studio 2022 overall.<\/p>\n 17.13 notes for reference.<\/a><\/p>\n Note:<\/strong> C++23 features can be used by either adding C++23 Features<\/h2>\n
\/std:c++latest<\/code> or\n\/std:c++23preview<\/code> to the command line. In addition, features used from unfinished standards may not\nhave full IntelliSense support.<\/p>\n\n
auto lambda = [] constexpr { }; \/\/ C++23: can now omit the '()' after the capture list.<\/code><\/pre>\n\n
if consteval<\/code> for C++23.<\/li>\n<\/ul>\nconstexpr int f(int) {\r\n if consteval { \/\/ C++23: previously this would be 'if (std::is_constant_evaluated()) { ... }'.\r\n return 42;\r\n }\r\n else {\r\n return 1337;\r\n }\r\n}\r\nint main(int argc, const char**) {\r\n static_assert(f(0) == 42);\r\n int x = f(argc);\r\n if (x != 1337) \/\/ Since 'f' cannot be evaluated at compile-time, the value here is '1337'\r\n \/\/ due to taking the 'else' branch in 'f'.\r\n return 1;\r\n}<\/code><\/pre>\n\n
enum Flags { Zero, One, Two };\r\nstatic_assert(One | Two);<\/code><\/pre>\n\n
auto lambda = [] [[nodiscard]] [[deprecated]] { return 10; };\r\nvoid f() {\r\n lambda(); \/\/ C++23: Attributes here will fire a deprecation warning and a discard of return value warning.\r\n}<\/code><\/pre>\n\n
static operator()<\/code>.<\/li>\nstatic operator[]<\/code>.<\/li>\n<\/ul>\nstruct Functor {\r\n static constexpr int operator()() { return 42; }\r\n static constexpr int operator[](int) { return 42; }\r\n};\r\nusing T1 = decltype(Functor::operator()()); \/\/ C++23: Deduces to 'int'.\r\nstatic_assert(Functor::operator()() == 42); \/\/ C++23: Can be used without creating a 'Functor' object.\r\n\r\nusing T2 = decltype(Functor::operator[](10)); \/\/ C++23: Deduces to 'int'.\r\nstatic_assert(Functor::operator[](10) == 42); \/\/ C++23: Can be used without creating a 'Functor' object.<\/code><\/pre>\nSmaller C++23 Items<\/h3>\n
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Compiler improvements for 17.14<\/h2>\n
C++\/CLI<\/h3>\n
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Diagnostics<\/h3>\n
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constexpr<\/code><\/h3>\n\n
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if consteval<\/code> would not properly be considered in consetxpr functions.\n\n
if consteval<\/code><\/a><\/li>\n<\/ul>\n<\/li>\n\n
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consteval<\/code> but not if it’s\nconstexpr<\/code>.<\/a><\/li>\n<\/ul>\n<\/li>\n\n
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C++ Modules<\/h3>\n
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static const<\/code> variable in a template causes C5260\nto incorrectly fire<\/a><\/li>\n<\/ul>\n<\/li>\n__declspec(dllimport)<\/code> would sometimes issue a linker\nerror when imported through a module.<\/p>\n\n
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auto<\/code> would sometimes not be resolved from a module.\n\n
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std::ranges<\/code> in modules where the compiler would issue a syntax error.\n\n
__vectorcall<\/code> functions in a module would sometimes not compile.\n\n
Conformance<\/h3>\n
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\/Zc:u8EscapeEncoding<\/code> for conformant encoding of escape sequences like u8″\\xFF”\n\n
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Reliability<\/h3>\n
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