Miscellaneous small diagnostics cleanup

compiler/rustc_trait_selection/src/traits/const_evaluatable.rs

@@ -117,7 +117,7 @@ pub fn is_const_evaluatable<'cx, 'tcx>(
                         {
                             err.span_help(
                                 tcx.def_span(def.did),
-                                &format!("try adding a `where` bound using this expression: where [u8; {}]: Sized", snippet),
+                                &format!("try adding a `where` bound using this expression: `where [u8; {}]: Sized`", snippet),
                             );
                         } else {
                             err.span_help(

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1780,7 +1780,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'tcx> for InferCtxt<'a, 'tcx> {
                             multispan.push_span_label(
                                 sp,
                                 format!(
-                                    "...if indirection was used here: `Box<{}>`",
+                                    "...if indirection were used here: `Box<{}>`",
                                     param.name.ident(),
                                 ),
                             );

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -1103,7 +1103,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 // This is currently not possible to trigger because E0038 takes precedence, but
                 // leave it in for completeness in case anything changes in an earlier stage.
                 err.note(&format!(
-                    "if trait `{}` was object safe, you could return a trait object",
+                    "if trait `{}` were object-safe, you could return a trait object",
                     trait_obj,
                 ));
             }

compiler/rustc_typeck/src/check/mod.rs

@@ -838,7 +838,7 @@ fn missing_items_err(
     // Obtain the level of indentation ending in `sugg_sp`.
     let indentation = tcx.sess.source_map().span_to_margin(sugg_sp).unwrap_or(0);
     // Make the whitespace that will make the suggestion have the right indentation.
-    let padding: String = (0..indentation).map(|_| " ").collect();
+    let padding: String = std::iter::repeat(" ").take(indentation).collect();
 
     for trait_item in missing_items {
         let snippet = suggestion_signature(&trait_item, tcx);

src/test/ui/const-generics/const_evaluatable_checked/cross_crate_predicate.stderr

@@ -4,7 +4,7 @@ error: unconstrained generic constant
 LL |     let _ = const_evaluatable_lib::test1::<T>();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: try adding a `where` bound using this expression: where [u8; std::mem::size_of::<T>() - 1]: Sized
+help: try adding a `where` bound using this expression: `where [u8; std::mem::size_of::<T>() - 1]: Sized`
   --> $DIR/auxiliary/const_evaluatable_lib.rs:6:10
    |
 LL |     [u8; std::mem::size_of::<T>() - 1]: Sized,
@@ -16,7 +16,7 @@ error: unconstrained generic constant
 LL |     let _ = const_evaluatable_lib::test1::<T>();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: try adding a `where` bound using this expression: where [u8; std::mem::size_of::<T>() - 1]: Sized
+help: try adding a `where` bound using this expression: `where [u8; std::mem::size_of::<T>() - 1]: Sized`
   --> $DIR/auxiliary/const_evaluatable_lib.rs:4:27
    |
 LL | pub fn test1<T>() -> [u8; std::mem::size_of::<T>() - 1]
@@ -28,7 +28,7 @@ error: unconstrained generic constant
 LL |     let _ = const_evaluatable_lib::test1::<T>();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: try adding a `where` bound using this expression: where [u8; std::mem::size_of::<T>() - 1]: Sized
+help: try adding a `where` bound using this expression: `where [u8; std::mem::size_of::<T>() - 1]: Sized`
   --> $DIR/auxiliary/const_evaluatable_lib.rs:6:10
    |
 LL |     [u8; std::mem::size_of::<T>() - 1]: Sized,
@@ -40,7 +40,7 @@ error: unconstrained generic constant
 LL |     let _ = const_evaluatable_lib::test1::<T>();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: try adding a `where` bound using this expression: where [u8; std::mem::size_of::<T>() - 1]: Sized
+help: try adding a `where` bound using this expression: `where [u8; std::mem::size_of::<T>() - 1]: Sized`
   --> $DIR/auxiliary/const_evaluatable_lib.rs:4:27
    |
 LL | pub fn test1<T>() -> [u8; std::mem::size_of::<T>() - 1]

src/test/ui/const-generics/const_evaluatable_checked/different-fn.stderr

@@ -4,7 +4,7 @@ error: unconstrained generic constant
 LL |     [0; size_of::<Foo<T>>()]
    |         ^^^^^^^^^^^^^^^^^^^
    |
-help: try adding a `where` bound using this expression: where [u8; size_of::<Foo<T>>()]: Sized
+help: try adding a `where` bound using this expression: `where [u8; size_of::<Foo<T>>()]: Sized`
   --> $DIR/different-fn.rs:10:9
    |
 LL |     [0; size_of::<Foo<T>>()]

src/test/ui/const_evaluatable/needs_where_clause.stderr

@@ -4,7 +4,7 @@ error: unconstrained generic constant
 LL |   b: [f32; complex_maths::<T>(N)],
    |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: try adding a `where` bound using this expression: where [u8; complex_maths::<T>(N)]: Sized
+help: try adding a `where` bound using this expression: `where [u8; complex_maths::<T>(N)]: Sized`
   --> $DIR/needs_where_clause.rs:11:12
    |
 LL |   b: [f32; complex_maths::<T>(N)],

src/test/ui/const_evaluatable/no_where_clause.stderr

@@ -4,7 +4,7 @@ error: unconstrained generic constant
 LL |   b: [f32; complex_maths(N)],
    |      ^^^^^^^^^^^^^^^^^^^^^^^
    |
-help: try adding a `where` bound using this expression: where [u8; complex_maths(N)]: Sized
+help: try adding a `where` bound using this expression: `where [u8; complex_maths(N)]: Sized`
   --> $DIR/no_where_clause.rs:10:12
    |
 LL |   b: [f32; complex_maths(N)],

src/test/ui/issues/issue-18919.stderr

@@ -14,7 +14,7 @@ help: you could relax the implicit `Sized` bound on `T` if it were used through
 LL | enum Option<T> {
    |             ^ this could be changed to `T: ?Sized`...
 LL |     Some(T),
-   |          - ...if indirection was used here: `Box<T>`
+   |          - ...if indirection were used here: `Box<T>`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-23281.stderr

@@ -14,7 +14,7 @@ help: you could relax the implicit `Sized` bound on `T` if it were used through
 LL | struct Vec<T> {
    |            ^ this could be changed to `T: ?Sized`...
 LL |     t: T,
-   |        - ...if indirection was used here: `Box<T>`
+   |        - ...if indirection were used here: `Box<T>`
 
 error: aborting due to previous error
 

src/test/ui/suggestions/adt-param-with-implicit-sized-bound.stderr

@@ -13,7 +13,7 @@ help: you could relax the implicit `Sized` bound on `T` if it were used through
   --> $DIR/adt-param-with-implicit-sized-bound.rs:18:10
    |
 LL | struct X<T>(T);
-   |          ^  - ...if indirection was used here: `Box<T>`
+   |          ^  - ...if indirection were used here: `Box<T>`
    |          |
    |          this could be changed to `T: ?Sized`...
 
@@ -68,7 +68,7 @@ help: you could relax the implicit `Sized` bound on `T` if it were used through
 LL | struct Struct3<T>{
    |                ^ this could be changed to `T: ?Sized`...
 LL |     _t: T,
-   |         - ...if indirection was used here: `Box<T>`
+   |         - ...if indirection were used here: `Box<T>`
 help: consider further restricting `Self`
    |
 LL |     fn func3() -> Struct3<Self> where Self: Sized;

src/test/ui/unsized/unsized-enum.stderr

@@ -13,7 +13,7 @@ help: you could relax the implicit `Sized` bound on `U` if it were used through
   --> $DIR/unsized-enum.rs:4:10
    |
 LL | enum Foo<U> { FooSome(U), FooNone }
-   |          ^            - ...if indirection was used here: `Box<U>`
+   |          ^            - ...if indirection were used here: `Box<U>`
    |          |
    |          this could be changed to `U: ?Sized`...
 

src/test/ui/unsized/unsized-inherent-impl-self-type.stderr

@@ -13,7 +13,7 @@ help: you could relax the implicit `Sized` bound on `Y` if it were used through
   --> $DIR/unsized-inherent-impl-self-type.rs:5:11
    |
 LL | struct S5<Y>(Y);
-   |           ^  - ...if indirection was used here: `Box<Y>`
+   |           ^  - ...if indirection were used here: `Box<Y>`
    |           |
    |           this could be changed to `Y: ?Sized`...
 

src/test/ui/unsized/unsized-struct.stderr

@@ -13,7 +13,7 @@ help: you could relax the implicit `Sized` bound on `T` if it were used through
   --> $DIR/unsized-struct.rs:4:12
    |
 LL | struct Foo<T> { data: T }
-   |            ^          - ...if indirection was used here: `Box<T>`
+   |            ^          - ...if indirection were used here: `Box<T>`
    |            |
    |            this could be changed to `T: ?Sized`...
 

src/test/ui/unsized/unsized-trait-impl-self-type.stderr

@@ -13,7 +13,7 @@ help: you could relax the implicit `Sized` bound on `Y` if it were used through
   --> $DIR/unsized-trait-impl-self-type.rs:8:11
    |
 LL | struct S5<Y>(Y);
-   |           ^  - ...if indirection was used here: `Box<Y>`
+   |           ^  - ...if indirection were used here: `Box<Y>`
    |           |
    |           this could be changed to `Y: ?Sized`...
 

src/test/ui/wf/wf-fn-where-clause.stderr

@@ -28,7 +28,7 @@ help: you could relax the implicit `Sized` bound on `T` if it were used through
 LL | struct Vec<T> {
    |            ^ this could be changed to `T: ?Sized`...
 LL |     t: T,
-   |        - ...if indirection was used here: `Box<T>`
+   |        - ...if indirection were used here: `Box<T>`
 
 error[E0038]: the trait `Copy` cannot be made into an object
   --> $DIR/wf-fn-where-clause.rs:12:16