On Fri, Jun 07, 2024 at 09:43:29AM +0000, Alice Ryhl wrote: > Peter Zijlstra <pet...@infradead.org> wrote: > > On Thu, Jun 06, 2024 at 09:09:00PM +0200, Miguel Ojeda wrote: > > > On Thu, Jun 6, 2024 at 7:19 PM Peter Zijlstra <pet...@infradead.org> > > > wrote: > > > > > > > > This is absolutely unreadable gibberish -- how am I supposed to keep > > > > this in sync with the rest of the static_call infrastructure? > > > > > > Yeah, they are macros, which look different from "normal" Rust code. > > > > Macros like CPP ? > > Yes, this patch series uses declarative macros, which are the closest > that Rust has to the C preprocessor. They are powerful, but just like > CPP, they can become pretty complicated and hard to read if you are > doing something non-trivial. > > The macro_rules! block is how you define a new declarative macro.
I'm sorry, but 30+ years of reading ! as NOT (or factorial) isn't going to go away. So I'm reading your macros do NOT rule. > The ($name:ident($($args:expr),* $(,)?)) part defines the arguments to > the declarative macro. This syntax means: > > 1. The input starts with any identifier, which we call $name. > 2. Then there must be a ( token. The above exaple fails, because the next token is :ident, whatever the heck that might be. Also, extra points for line-noise due to lack of whitespace. > So for example, you might invoke the macro like this: > > static_call!(tp_func_my_tracepoint(__data, &mut my_task_struct)); static_call NOT (blah dog blah); > Inside the macro, you will see things such as: > $crate::macros::paste! { $crate::bindings:: [<__SCK__ $name >]; } > > The Rust syntax for invoking a macro has an exclamation mark after the Like I said before, the creator of Rust must've been an esoteric language freak and must've wanted to make this unreadable on purpose :/ Also, why the white space beteen the :: scope operator and the [< thing? that's just weird. I would then expect the output to be: ...::bindings:: __SCK__my_static_key > name, so you know that $crate::macros::paste is a macro. The `paste` > macro just emits its input unchanged, except that any identifiers > between [< and >] are concatenated into a single identifier. So if $name > is my_static_key, then the above invocation of paste! emits: > > $crate::bindings::__SCK__my_static_key; But it doesn't, so it isn't unmodified, it seems to strip whitespace. > The $crate::bindings module is where the output of bindgen goes, so this > should correspond to the C symbol called __SCK__my_static_key. > > > > Is there something we could do to help here? I think Alice and others > > > would be happy to explain how it works and/or help maintain it in the > > > future if you prefer. > > > > Write a new language that looks more like C -- pretty please ? :-) > > > > Mostly I would just really like you to just use arm/jump_label.h, > > they're inline functions and should be doable with IR, no weirdo CPP > > involved in this case. > > I assume that you're referring to static_key_false here? I don't think > that function can be exposed using IR because it passes the function > argument called key as an "i" argument to an inline assembly block. Any > attempt to compile static_key_false without knowing the value of key at > compile time will surely fail to compile with the > > invalid operand for inline asm constraint 'i' > > error. You can have clang read the header files and compile them into Intermediate-Representation, and have it splice the lot into the Rust crap's IR and voila, compile time. You just need to extend the rust thing to be able to consume C header files.