> Maybe it's because the C was four times older, but I think it's because in the real world you don't end up writing that mythical portable C code too often.
It's because C, over time, went from a bunch of almost compatible implementations, to a standard that differed a little from every existing implementation, to a standard that is updated every decade or so, which is then implemented by a bunch of different products, with enough ambiguity in the standard (UB) that there will be differences between compilers and versions of compilers.
Rust is a single implementation. Always has been.
It's a single product, so you code to the product. The product has no external forcing function, like a language standard, that produces changes every decade. When you write Rust, you aren't thinking "Wait, lets make sure this works on the Watcom compiler too".
If Rust code cannot compile 30 years later, that's a failure on the language, because the single implementation is in full control of compatibility. If C code cannot compile 30 years later, that's not a failure of the language, because the implementation in 30 years has had external pressure forcing changes.
People often forget that Rust is a product, C is a specification.
In practice the cadence is exactly half that of WG21's breakneck C++ pace. Every six years. C11, C17, C23 so far and C2y is expected to land before the end of this decade.
But anyway, all I can do is report the observable fact. If you want to say it's because GCC 15 is a different product from GCC 4 whereas rustc 1.99 is the same product as rustc 1.49 then I guess you can re-phrase my position as "In C you will keep needing new products and that sucks" if you like.
In theory, in practice many C developers only know "My C Compiler standard", and are usually surprised that some of their expectations aren't even part of ISO C PDF specification.
Then they get irritated that not all C compiler vendors have the same language extensions or implementation defined behaviours they got used to rely on.
True. In C, it's hard to know what's defined where and what dependencies one is even using unknowingly. The only help is to build on multiple platforms from early on, this will reduce the pain of porting to new platforms later.
It's because C, over time, went from a bunch of almost compatible implementations, to a standard that differed a little from every existing implementation, to a standard that is updated every decade or so, which is then implemented by a bunch of different products, with enough ambiguity in the standard (UB) that there will be differences between compilers and versions of compilers.
Rust is a single implementation. Always has been.
It's a single product, so you code to the product. The product has no external forcing function, like a language standard, that produces changes every decade. When you write Rust, you aren't thinking "Wait, lets make sure this works on the Watcom compiler too".
If Rust code cannot compile 30 years later, that's a failure on the language, because the single implementation is in full control of compatibility. If C code cannot compile 30 years later, that's not a failure of the language, because the implementation in 30 years has had external pressure forcing changes.
People often forget that Rust is a product, C is a specification.
In practice the cadence is exactly half that of WG21's breakneck C++ pace. Every six years. C11, C17, C23 so far and C2y is expected to land before the end of this decade.
But anyway, all I can do is report the observable fact. If you want to say it's because GCC 15 is a different product from GCC 4 whereas rustc 1.99 is the same product as rustc 1.49 then I guess you can re-phrase my position as "In C you will keep needing new products and that sucks" if you like.
Then they get irritated that not all C compiler vendors have the same language extensions or implementation defined behaviours they got used to rely on.