You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: specializer.rs
    path of file: ./repos/rust-gpu/crates/rustc_codegen_spirv/src/linker
    
    the code of the file until where you have to start completion: //! Specialize globals (types, constants and module-scoped variables) and functions,
//! to legalize a SPIR-V module representing a "family" of types with a single type,
//! by treating some globals and functions as "generic", inferring minimal sets
//! of "generic parameters", and "monomorphizing" them (i.e. expanding them into
//! one specialized copy per distinctly parameterized instance required).
//!
//! For now, this is only used for pointer type storage classes, because
//! Rust's pointer/reference types don't have an "address space" distinction,
//! and we also wouldn't want users to annotate every single type anyway.
//!
//! # Future plans
//!
//! Recursive data types (using `OpTypeForwardPointer`) are not supported, but
//! here is an outline of how that could work:
//! * groups of mutually-recursive `OpTypeForwardPointer`s are computed via SCCs
//! * each mutual-recursive group gets a single "generic" parameter count, that all
//!   pointer types in the group will use, and which is the sum of the "generic"
//!   parameters of all the leaves referenced by the pointer types in the group,
//!   ignoring the pointer types in the group themselves
/
    
    fn infer_function(&mut self, func: &Function) -> Option<Replacements> {
        let func_id = func.def_id().unwrap();

        let param_count = self
            .generics
            .get(&func_id)
            .map_or(0, |generic| generic.param_count);

        let (param_values, replacements) = {
            let mut infer_cx = InferCx::new(self);
            infer_cx.instantiate_function(func);

            // FIXME(eddyb) dedup this with `collect_generics`.
            let param_values = infer_cx.infer_var_values[..param_count as usize]
                .iter()
                .map(|v| v.map_var(|InferVar(i)| Param(i)));
            // Only allocate `param_values` if they constrain parameters.
            let param_values = if param_values.clone().any(|v| v != Value::Unknown) {
                Some(param_values.collect())
            } else {
                None
            };

            (
                param_values,
                infer_cx.into_replacements(..Param(param_count)),
            )
        };

        if let Some(generic) = self.generics.get_mut(&func_id) {
            // All constraints `func` could have from `collect_generics`
            // would have to come from its `OpTypeFunction`, but types don't have
            // internal constraints like e.g. `OpConstant*` and `OpVariable` do.
            assert!(generic.param_values.is_none());

            generic.param_values = param_values;
            generic.replacements = replacements;

            None
        } else {
            Some(replacements)
        }
    }