loadfn does not need to be mutable?

[hofstee]

I'm seeing this warning on rust nightly:

warning: variable does not need to be mutable
 --> out/gl_bindings.rs:9:23
  |
9 |         fn metaloadfn(mut loadfn: &mut FnMut(&str) -> *const __gl_imports::raw::c_void,
  |                       ----^^^^^^
  |                       |
  |                       help: remove this `mut`
  |
  = note: #[warn(unused_mut)] on by default

Is this necessary or am I doing something wrong? Is there a way I can configure it to not have this warning in my build.rs?

[brendanzab]

Hmm, this might be an issue with how we are generating the bindings. What is the source code around out/gl_bindings.rs:9:23?

[brendanzab]

In the interim you'll be able to suppress this by adding the #[allow(unused_mut)] attribute to wherever you reference the bindings, but we should really fix this in the generator.

[hofstee]

Here's the first few lines of the generated code:

        mod __gl_imports {
            pub use std::mem;
            pub use std::os::raw;
        }
    

        #[inline(never)]
        fn metaloadfn(mut loadfn: &mut FnMut(&str) -> *const __gl_imports::raw::c_void,
                      symbol: &str,
                      fallbacks: &[&str]) -> *const __gl_imports::raw::c_void {
            let mut ptr = loadfn(symbol);
            if ptr.is_null() {
                for &sym in fallbacks {
                    ptr = loadfn(sym);
                    if !ptr.is_null() { break; }
                }
            }
            ptr
        }
    

        pub mod types {
            #![allow(non_camel_case_types, non_snake_case, dead_code, missing_copy_implementations)]

[brendanzab]

Yeah, it seems that the mut on mut loadfn is unnecessary, due to the &mut on the type! We should fix the generator to not generate this 🤔