3 ms·

This craziness (a belief that if you don't specify what something means it must have some "obvious" behaviour that is coincidentally always whatever the program

This craziness (a belief that if you don't specify what something means it must have some "obvious" behaviour that is coincidentally always whatever the programmer wanted) is endemic in C and C++ communities. Right now, notionally serious people are making the case that C++ should enshrine the "bag-of-bits" model of pointers which is exactly this sort of stupidity. At first it looks like they want pointers are addresses which is kinda dumb but whatever, and you keep reading and they're like aha, also I should be able to dereference my bag-of-bits and have that work too... Full blown Provenance Via Integers, expect to spend the next forty years trying to specify how any of the optimisations you rely on can survive the resulting tangle, say hi to anybody who wanted Consume ordering and is still waiting.

marssaxman 3y ago
> This craziness (a belief that if you don't specify what something means it must have some "obvious" behaviour that is coincidentally always whatever the programmer wanted) is endemic in C and C++ communities. That belief is endemic because that is the way things actually worked for many years! Compilers used to give us the obvious behavior, because they weren't smart enough to outfox us by doing anything else, because the CPUs we used were not fast enough to let them do the kinds of comprehensive optimization analyses which are now routine.
- gpderetta 3y ago
  No. The reality is that every new generation of programmers is completely comfortable with optimizations that existed before it started programming and surprised by optimizations added after that. Today we take for granted SSA, extensive interprocedural optimizations, value-range propagation and LTO. Before that was aggressive inlining and SRA; before that was smart register allocation and stack optimizations. Even before that it was instruction scheduling. Each one of these optimizations have broken someone's code.

marssaxman 3y ago

> This craziness (a belief that if you don't specify what something means it must have some "obvious" behaviour that is coincidentally always whatever the programmer wanted) is endemic in C and C++ communities. That belief is endemic because that is the way things actually worked for many years! Compilers used to give us the obvious behavior, because they weren't smart enough to outfox us by doing anything else, because the CPUs we used were not fast enough to let them do the kinds of comprehensive optimization analyses which are now routine.

gpderetta 3y ago
No. The reality is that every new generation of programmers is completely comfortable with optimizations that existed before it started programming and surprised by optimizations added after that. Today we take for granted SSA, extensive interprocedural optimizations, value-range propagation and LTO. Before that was aggressive inlining and SRA; before that was smart register allocation and stack optimizations. Even before that it was instruction scheduling. Each one of these optimizations have broken someone's code.