derive Copy, Clone, PartialEq, Eq for ImplTraitContext

Author: spastorino

compiler/rustc_ast_lowering/src/lib.rs

@@ -246,7 +246,7 @@ pub trait ResolverAstLowering {
 
 /// Context of `impl Trait` in code, which determines whether it is allowed in an HIR subtree,
 /// and if so, what meaning it has.
-#[derive(Debug)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 enum ImplTraitContext {
     /// Treat `impl Trait` as shorthand for a new universal generic parameter.
     /// Example: `fn foo(x: impl Debug)`, where `impl Debug` is conceptually