Add stable_mir::ty::GenericParamDefKind conversion

Author: spastorino

Cargo.lock

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+formality-types = { path = "../formality-types" }

crates/formality-smir/Cargo.toml

@@ -1,7 +1,28 @@
+#![feature(rustc_private)]
+
+extern crate rustc_driver;
+extern crate rustc_smir;
+
+use rustc_smir::stable_mir;
+
 /// Trait used to convert from Stable MIR to Formality types.
 pub trait ToFormality {
     /// The formality representation of the stable MIR type implementing ToFormality.
     type T;
     /// Converts an object to the equivalent Formality representation.
     fn formality(&self) -> Self::T;
 }
+
+impl ToFormality for stable_mir::ty::GenericParamDefKind {
+    type T = formality_types::derive_links::ParameterKind;
+
+    fn formality(&self) -> Self::T {
+        use formality_types::derive_links::ParameterKind;
+
+        match self {
+            stable_mir::ty::GenericParamDefKind::Lifetime => ParameterKind::Lt,
+            stable_mir::ty::GenericParamDefKind::Type { .. } => ParameterKind::Ty,
+            stable_mir::ty::GenericParamDefKind::Const { .. } => ParameterKind::Const,
+        }
+    }
+}