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by instig007 207 days ago
> Once you get to that point, you might as well create and learn a different language.

Nope, it's still incredibly valuable to be able to c++14 and c++26 two different translation units and then later link them together (all without leaving the familiar toolchains and ecosystems). That's how big legacy projects can evolve towards better safety incrementally.
2 comments
MontagFTB 207 days ago
If the Standard has anything to say about compatibility between different language versions, I doubt many developers know those details. This is breeding ground for ODR violations, as you’re likely using compilers with different output (as they are built in different eras of the language’s lifetime) especially at higher optimization settings.

This flies in the face of modern principles like building all your C++, from source, at the same time, with the same settings.

Languages like Rust include these settings in symbol names as a hash to prevent these kinds of issues by design. Unless your whole team is a moderate-level language lawyer, you must enforce this by some other means or risk some really gnarly issues.

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PaulDavisThe1st 207 days ago
> Languages like Rust include these settings in symbol names as a hash to prevent these kinds of issues by design.

Historically, C++ compilers' name mangling scheme for symbols did precisely the same thing. The 2000-2008 period for gcc was particularly painful since the compiler developers really used it very frequently, to "prevent these kinds of issues by design". The only reason most C++ developers don't think about this much any more is that most C++ compilers haven't needed to change their demangling algorithm for a decade or more.

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MontagFTB 207 days ago
C++’s name mangling scheme handles some things like namespaces and overloading, but it does not account for other settings that can affect the ABI layer of the routine, like compile time switches or optimization level.
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PaulDavisThe1st 207 days ago
The name mangling scheme was changed to reflect things other than namespaces and overloading, it was modified to reflect fundamental compiler version incompatibilities (i.e. the ABI)

Optimization level should never cause link time or run time issues; if it does I'd consider that a compiler/linker bug, not an issue with the language.

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gwbas1c 206 days ago
Many languages have ways to call into old code. C++ allows calling C; so does Objective C.
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