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The problem is that this group of programmers are operating on a language that is almost-but-not-quite C. They would very much like to believe that there is a

The problem is that this group of programmers are operating on a language that is almost-but-not-quite C. They would very much like to believe that there is a set of flags which make the compiler run in the mode of almost-C that the application engineers thought they were working with all those years ago. But the fact of the matter is that the ISO C standard is the only contract which has been written down between application authors and compiler authors. No amount of flags are enough to guarantee that a particular individual's expectation of almost-C will be equal to what their compiler is producing. What the industry needs to move forward are two things. A set of tools that can help identify more cases of almost-C that need to be ported to C. We're getting this, in the form of UBSAN, ASAN, and their kin. The other thing is for the veterans to accept that their particular brand of almost-C doens't actually exist. There's only ISO C. For almost three decades now, that's all we've had. the engineering cost of trying to keep almost-C alive is just too high to keep paying.

mpweiher 8y ago
This is a common trope ("language users are just ignorant"), but couldn't be more wrong. There actually is explicit language in the C standard that gives a range of "permissible behaviours": Permissible undefined behavior ranges from ignoring the situation completely with unpredictable results, to behaving during translation or program execution in a documented manner characteristic of the environment (with or without the issuance of a diagnostic message), to terminating a translation or execution (with the issuance of a diagnostic message). This gives a range of permissible behaviours, and what current compilers do with UB clearly does not fall into that range, whereas it closely matches the expectations of those "ignorant" language users. In the first ANSI/ISO C standard, this language was binding, it was only in later version that it was declared non-binding. So the language is in the standard, but implementers are free to ignore it and still call themselves standards-compliant, which they do with abandon. > the ISO C standard is the only contract This is also a common trope, and also not (completely) true. In fact, the C standard very explicitly says that the standard by itself is not sufficient to make a useful/usable implementation! There is a way in which this sentiment is becoming true, which is that we used to have a different contract between user and compiler writer: a sales contract. Users were also customers, and if you produced a compiler that only conformed to the standard, your customers would stop giving you money. Today, compilers are largely free for users, and therefore the standard actually is in many ways the only "contract" between user and writer. So that's a problem, as the goals and incentives aren't aligned.
- brandmeyer 8y ago
  > This is a common trope ("language users are just ignorant"), but couldn't be more wrong. It isn't a matter of ignorance; using those switches to get a vendor-specific version of not-quite-C is a matter of willful disobedience.
  - mpweiher 8y ago
    Hmmm...actually, those switches turn the no-longer-C back into C.

mpweiher 8y ago

This is a common trope ("language users are just ignorant"), but couldn't be more wrong. There actually is explicit language in the C standard that gives a range of "permissible behaviours": Permissible undefined behavior ranges from ignoring the situation completely with unpredictable results, to behaving during translation or program execution in a documented manner characteristic of the environment (with or without the issuance of a diagnostic message), to terminating a translation or execution (with the issuance of a diagnostic message). This gives a range of permissible behaviours, and what current compilers do with UB clearly does not fall into that range, whereas it closely matches the expectations of those "ignorant" language users. In the first ANSI/ISO C standard, this language was binding, it was only in later version that it was declared non-binding. So the language is in the standard, but implementers are free to ignore it and still call themselves standards-compliant, which they do with abandon. > the ISO C standard is the only contract This is also a common trope, and also not (completely) true. In fact, the C standard very explicitly says that the standard by itself is not sufficient to make a useful/usable implementation! There is a way in which this sentiment is becoming true, which is that we used to have a different contract between user and compiler writer: a sales contract. Users were also customers, and if you produced a compiler that only conformed to the standard, your customers would stop giving you money. Today, compilers are largely free for users, and therefore the standard actually is in many ways the only "contract" between user and writer. So that's a problem, as the goals and incentives aren't aligned.

brandmeyer 8y ago
> This is a common trope ("language users are just ignorant"), but couldn't be more wrong. It isn't a matter of ignorance; using those switches to get a vendor-specific version of not-quite-C is a matter of willful disobedience.
- mpweiher 8y ago
  Hmmm...actually, those switches turn the no-longer-C back into C.