HeroicKatora
With regards to standard use, for many users the scenario is definitely not common. I'd rather rustc be an effective screw driver and a separate hammer be built than try to mangle both into the same tool. By that I mean, it's very clear which portion of the compiler must be repurposed here. The hard question is whether the architecture is amenable to alternative linker backends that serve your use-case. I'm afraid I can't answer that conclusively. Only so much, the conceptual conflict of Rust is that linkining is a very memory-safety critical part of the process. And with its compilation module model it relinks everything into the resulting binary / library which includes a large std and dependency tree even if much of this is removed by the step. Maybe that can be changed; and relying a tool whose interface was ultimately designed with C in mind is also far from optimal to compute those outputs and inputs. It's hard to say how much of it stems from compatibility concerns and compatibility overheads and how much is fundamental to the language's design which could be shed for a pure build process.
With regards to C++, I suspect it's rooted in the fact that parsing it requires in principle the implementation of a complete consteval engine. The language has a dependency loop between parsing and codegen. This of course, is not how data should be laid out for executing fast programs on it. It's quite concerning given the specifications still contains the bold faced lie that "The disambiguation is purely syntactic" (6.8; 1) for typenames vs non-typenames to parse constructors from declarations which at the present can require arbitrary template specialization. It might be interesting to see if those two headers in your example already execute some of these dependency loops but it's hard for me to think of an experiment to validate any of this. Maybe you have ideas, is there something like time-passes?
I think the test is uultimately non-sensical for the question being posed here. It doesn't reveal anything insightful about scaling to real world program sizes, either. The time of rustc is dominated by the platform linker anyways. Sure, one might argue that this points out Rust as relying too much on the linker and creating too many unused symbols. But the question of whether this is caused by the language and in particular its syntactical choices .. should at that point be answered with probably not. It's not a benchmark you want to compare by percentage speedups anyways since it's probably dominated by constant time costs for any of the batteries included standard library languages compared to C.
In my opinion, C has tried to serve two masters and they made a screw-hammer in the process.
The rest of the field has moved on significantly. We want portable behavior, not implementation-defined vomit that will leave you doubting whether porting introduces new UB paths that you haven't already fully checked against (by, e.g. varying the size of integers in such a way some promotion is changed to something leading to signed overflow; or bounds checking is ineffective).
The paragraph further down about explicitly and swiftly rejecting a validation test suite should also read as a warning. Not only would the proposal of modern software development without a test suite get you swiftly fired today, but they're explicitly acknowledging the insurmountable difficulties in producing any code with consistent cross-implementation behavior. But in the time since then, other languages have demonstrated you can reap many of the advantages of close-to-the-metal without compromising on behavior consistency in cross-target behavior, at least for many relevant real-word cases.
They really knew what they were building, a compromise. But that gets cherry-picked into absurdity such as stating C is portable in present-tense or that any inherent properties make it assembly-like. It's neither.
> you [people; …] cannot change. Cause you're human afterall. […] So I began to compose a new story for them [aka. artificial intelligence]. It begins with […] the choices they will have to make; and the people they will decide to become.