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> I think we should try to transition code to the current ISO standard and in almost all cases this will just work without problems. In the few cases, where it

by sgbeal 3y ago

> I think we should try to transition code to the current ISO standard and in almost all cases this will just work without problems. In the few cases, where it does not, it is usually for a very good reason. Microsoft's C compiler did not support C99 until something like 15 years after the standard came out (and reportedly (according to colleagues who use that platform) still doesn't support certain features of it). It happens with surprising frequency that someone reports to the sqlite project that The Latest Version no longer works on their pre-2005 environment and they'd like to see it patched to work there. My point is: users of a given platform might not be able to use The Latest Stuff (or anywhere near it, for that matter) because their OS vendor is reticent, because they have to support an old platform which is not targeted by newer tools, or for whatever other reason. > Now, nobody is stopping compilers from supporting old language modes, but it adds a lot of complexity, ... i don't doubt that, and i do sympathize with the maintainers. i'm not saying they should never ever remove C89 support, but if they do then there needs to be an alternative, like a fork of the last compiler version which supported it, maintained at least to the extent that the rare genuine compiler bugs can be resolved.

uecker 3y ago
Microsoft declared C dead and wanted that everybody transitions to C++. Luckily this changed a bit and MSVC now supports newer standards. Also there are now other alternatives on Windows. So I do not think there is a good reason to put everything on standstill anymore. C needs to evolve and old code must be maintained. For me, this this means that code should be transitioned to newer standards. In no other industry would it be acceptable to ignore current industry standards. Now, I do understand that some projects do not want to use newer features for portability reasons. But this does not mean that they couldn't be compatible with a newer ISO C modes as well. Being compliant with C 17 does not necessarily mean one has to use new features.
pjmlp 3y ago
Microsoft considered C done, as clarified by Herb Sutter. https://herbsutter.com/2012/05/03/reader-qa-what-about-vc-and-c99/ https://herbsutter.com/2012/05/03/reader-qa-what-about-vc-an... They only kept updating their C support to the extent required by ISO C++ requirements, and some key customers. Anyone else still dependent on C was suggested to use clang, this is also why clang is part of Visual Studio compiler suite nowadays. Around the time the Microsoft <3 Linux stuff started, they decided to backtrack on this matter, and started updating their C support, however since C11 made a couple of stuff from C99 optional, they decided to skip on those. VLAs have anyway been proven a rich source of exploits, to the extent Google has sponsored the work to clean up the Linux kernel from all uses of them. https://www.phoronix.com/news/Linux-Kills-The-VLA https://www.phoronix.com/news/Linux-Kills-The-VLA
- uecker 3y ago
  The VLA security problems are a bit of a myth. In the kernel it may be some problem, but with stack clash protection (which one should activate anyway) there isn't really a inherent security issue anymore. The code quality improvements of using VLAs usually make it worth using them IMHO.
  - pjmlp 3y ago
    A myth that was worth every penny fixing it, as per Google.
    - uecker 3y ago
      Do you have link? BTW: I was tangentially involved in this effort...
      - pjmlp 3y ago
        It was on my original comment. Also there were a couple of talks from Linux Plumbers Conference given by Kees Cook, if I recall correctly.
        uecker 3y ago
        I now regret helping with this effort, since people use it as arguments against using VLAs in general, although in my opinion this is clearly the wrong conclusion outside of the kernel. VLAs are basically always superior to the next best alternative: They are safer than alloca() (and standard's compliant), they are faster than heap allocation (and similar safe), and use less stack and allow better bounds checking than a worst-case fixed-size arrays on the stack (but are slower).

by sgbeal 3y ago

uecker 3y ago

Microsoft declared C dead and wanted that everybody transitions to C++. Luckily this changed a bit and MSVC now supports newer standards. Also there are now other alternatives on Windows. So I do not think there is a good reason to put everything on standstill anymore. C needs to evolve and old code must be maintained. For me, this this means that code should be transitioned to newer standards. In no other industry would it be acceptable to ignore current industry standards. Now, I do understand that some projects do not want to use newer features for portability reasons. But this does not mean that they couldn't be compatible with a newer ISO C modes as well. Being compliant with C 17 does not necessarily mean one has to use new features.

pjmlp 3y ago

Microsoft considered C done, as clarified by Herb Sutter. https://herbsutter.com/2012/05/03/reader-qa-what-about-vc-and-c99/ https://herbsutter.com/2012/05/03/reader-qa-what-about-vc-an... They only kept updating their C support to the extent required by ISO C++ requirements, and some key customers. Anyone else still dependent on C was suggested to use clang, this is also why clang is part of Visual Studio compiler suite nowadays. Around the time the Microsoft <3 Linux stuff started, they decided to backtrack on this matter, and started updating their C support, however since C11 made a couple of stuff from C99 optional, they decided to skip on those. VLAs have anyway been proven a rich source of exploits, to the extent Google has sponsored the work to clean up the Linux kernel from all uses of them. https://www.phoronix.com/news/Linux-Kills-The-VLA https://www.phoronix.com/news/Linux-Kills-The-VLA

uecker 3y ago
The VLA security problems are a bit of a myth. In the kernel it may be some problem, but with stack clash protection (which one should activate anyway) there isn't really a inherent security issue anymore. The code quality improvements of using VLAs usually make it worth using them IMHO.
- pjmlp 3y ago
  A myth that was worth every penny fixing it, as per Google.
  - uecker 3y ago
    Do you have link? BTW: I was tangentially involved in this effort...
    - pjmlp 3y ago
      It was on my original comment. Also there were a couple of talks from Linux Plumbers Conference given by Kees Cook, if I recall correctly.
      - uecker 3y ago
        I now regret helping with this effort, since people use it as arguments against using VLAs in general, although in my opinion this is clearly the wrong conclusion outside of the kernel. VLAs are basically always superior to the next best alternative: They are safer than alloca() (and standard's compliant), they are faster than heap allocation (and similar safe), and use less stack and allow better bounds checking than a worst-case fixed-size arrays on the stack (but are slower).