Improve implicit self mutability suggestions.

This commit adds an `ImplicitSelfKind` to the HIR and the MIR that keeps
track of whether a implicit self argument is immutable by-value, mutable
by-value, immutable reference or mutable reference so that the addition
of the `mut` keyword can be suggested for the immutable by-value case.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/librustc/ich/impls_hir.rs b/src/librustc/ich/impls_hir.rs
index bc2eb5f442b..2097e4faf07 100644
--- a/src/librustc/ich/impls_hir.rs
+++ b/src/librustc/ich/impls_hir.rs
@@ -349,7 +349,7 @@ impl_stable_hash_for!(struct hir::FnDecl {
     inputs,
     output,
     variadic,
-    has_implicit_self
+    implicit_self
 });
 
 impl_stable_hash_for!(enum hir::FunctionRetTy {
@@ -357,6 +357,14 @@ impl_stable_hash_for!(enum hir::FunctionRetTy {
     Return(t)
 });
 
+impl_stable_hash_for!(enum hir::ImplicitSelfKind {
+    Imm,
+    Mut,
+    ImmRef,
+    MutRef,
+    None
+});
+
 impl_stable_hash_for!(struct hir::TraitRef {
     // Don't hash the ref_id. It is tracked via the thing it is used to access
     ref_id -> _,