[paulmd]

I don't remember the exact specifics, but Fortran disallows some of the constructs that C/C++ struggle with aliasing on, so Fortran can often be (safely) optimized to much higher-performance code because of this limitation/knowledge.

Like, it's always seemed like there's a certain amount of fatalism around Undefined Behavior in C/C++, like this is somehow how it has to be to write fast code but... it's not. You can just declare things as actually forbidden rather than just letting the compiler identify a boo-boo and silently do whatever the hell it wants.

Of course it's not the right tool for every task, I don't think you'd write bit-twiddling microcontroller stuff in fortran, or systems programming. But for the HPC space, and other "scientific" code? Fortran is a good match and very popular despite having an ancient legacy even by C/C++ standards (both have, of course, been updated through time). Little less flexible/general, but that allows less-skilled programmers (scientists are not good programmers) to write fast code without arcane knowledge of the gotchas of C/C++ compiler magic.

[jabl]

> I don't remember the exact specifics, but Fortran disallows some of the constructs that C/C++ struggle with aliasing on, so Fortran can often be (safely) optimized to much higher-performance code because of this limitation/knowledge.

For a crude approximation, Fortran is somewhat equivalent to C code where all pointer function arguments are marked with the restrict keyword.

> Like, it's always seemed like there's a certain amount of fatalism around Undefined Behavior in C/C++, like this is somehow how it has to be to write fast code but... it's not. You can just declare things as actually forbidden rather than just letting the compiler identify a boo-boo and silently do whatever the hell it wants.

Well, it's kind more dangerous than C, in this aspect. The aliasing restriction is a restriction on the Fortran programmer; the compiler or runtime is not required to diagnose it, meaning that the Fortran compiler is allowed to optimize assuming that two pointers don't alias.

That being said, in general I'd say Fortran has less footguns than C or C++, and is thus often a better choice for a domain expert that just wants to crunch numbers.