Move StatementAsExpression to where it's actually used.

Also minimize some visibilities in the destination file.

compiler/rustc_middle/src/traits/mod.rs

@@ -514,12 +514,6 @@ impl<'tcx> ObligationCauseCode<'tcx> {
 #[cfg(target_pointer_width = "64")]
 rustc_data_structures::static_assert_size!(ObligationCauseCode<'_>, 48);
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
-pub enum StatementAsExpression {
-    CorrectType,
-    NeedsBoxing,
-}
-
 #[derive(Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
 #[derive(TypeVisitable, TypeFoldable)]
 pub struct MatchExpressionArmCause<'tcx> {

compiler/rustc_trait_selection/src/error_reporting/infer/suggest.rs

@@ -10,7 +10,6 @@ use rustc_hir::def::Res;
 use rustc_hir::{MatchSource, Node};
 use rustc_middle::traits::{
     IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
-    StatementAsExpression,
 };
 use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::print::with_no_trimmed_paths;
@@ -26,8 +25,14 @@ use crate::errors::{
     SuggestTuplePatternMany, SuggestTuplePatternOne, TypeErrorAdditionalDiags,
 };
 
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+enum StatementAsExpression {
+    CorrectType,
+    NeedsBoxing,
+}
+
 #[derive(Clone, Copy)]
-pub enum SuggestAsRefKind {
+enum SuggestAsRefKind {
     Option,
     Result,
 }
@@ -382,7 +387,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         }
     }
 
-    pub fn suggest_function_pointers_impl(
+    pub(crate) fn suggest_function_pointers_impl(
         &self,
         span: Option<Span>,
         exp_found: &ty::error::ExpectedFound<Ty<'tcx>>,
@@ -518,7 +523,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         }
     }
 
-    pub fn should_suggest_as_ref_kind(
+    fn should_suggest_as_ref_kind(
         &self,
         expected: Ty<'tcx>,
         found: Ty<'tcx>,
@@ -588,8 +593,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     ) -> Option<TypeErrorAdditionalDiags> {
         /// Find the if expression with given span
         struct IfVisitor {
-            pub found_if: bool,
+            found_if: bool,
-            pub err_span: Span,
+            err_span: Span,
         }
 
         impl<'v> Visitor<'v> for IfVisitor {
@@ -736,7 +741,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     /// Be helpful when the user wrote `{... expr; }` and taking the `;` off
     /// is enough to fix the error.
-    pub fn could_remove_semicolon(
+    fn could_remove_semicolon(
         &self,
         blk: &'tcx hir::Block<'tcx>,
         expected_ty: Ty<'tcx>,
@@ -816,7 +821,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
     /// Suggest returning a local binding with a compatible type if the block
     /// has no return expression.
-    pub fn consider_returning_binding_diag(
+    fn consider_returning_binding_diag(
         &self,
         blk: &'tcx hir::Block<'tcx>,
         expected_ty: Ty<'tcx>,