Diagnostics should start lowercase

src/librustc/traits/error_reporting.rs

@@ -1156,7 +1156,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 err.span_help(impl_span, "trait impl with same name found");
                 let trait_crate = self.tcx.crate_name(trait_with_same_path.krate);
                 let crate_msg = format!(
-                    "Perhaps two different versions of crate `{}` are being used?",
+                    "perhaps two different versions of crate `{}` are being used?",
                     trait_crate
                 );
                 err.note(&crate_msg);

src/librustc_ast_passes/feature_gate.rs

@@ -413,7 +413,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                 self.check_extern(bare_fn_ty.ext);
             }
             ast::TyKind::Never => {
-                gate_feature_post!(&self, never_type, ty.span, "The `!` type is experimental");
+                gate_feature_post!(&self, never_type, ty.span, "the `!` type is experimental");
             }
             _ => {}
         }

src/librustc_builtin_macros/test.rs

@@ -325,7 +325,7 @@ fn should_panic(cx: &ExtCtxt<'_>, i: &ast::Item) -> ShouldPanic {
                              `expected = \"error message\"`",
                         )
                         .note(
-                            "Errors in this attribute were erroneously \
+                            "errors in this attribute were erroneously \
                                 allowed and will become a hard error in a \
                                 future release.",
                         )

src/librustc_lint/builtin.rs

@@ -657,7 +657,7 @@ impl EarlyLintPass for AnonymousParameters {
                                 )
                                 .span_suggestion(
                                     arg.pat.span,
-                                    "Try naming the parameter or explicitly \
+                                    "try naming the parameter or explicitly \
                                     ignoring it",
                                     format!("_: {}", ty_snip),
                                     appl,
@@ -1934,21 +1934,21 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidValue {
             use rustc::ty::TyKind::*;
             match ty.kind {
                 // Primitive types that don't like 0 as a value.
-                Ref(..) => Some((format!("References must be non-null"), None)),
+                Ref(..) => Some((format!("references must be non-null"), None)),
                 Adt(..) if ty.is_box() => Some((format!("`Box` must be non-null"), None)),
-                FnPtr(..) => Some((format!("Function pointers must be non-null"), None)),
-                Never => Some((format!("The never type (`!`) has no valid value"), None)),
+                FnPtr(..) => Some((format!("function pointers must be non-null"), None)),
+                Never => Some((format!("the `!` type has no valid value"), None)),
                 RawPtr(tm) if matches!(tm.ty.kind, Dynamic(..)) =>
                 // raw ptr to dyn Trait
                 {
-                    Some((format!("The vtable of a wide raw pointer must be non-null"), None))
+                    Some((format!("the vtable of a wide raw pointer must be non-null"), None))
                 }
                 // Primitive types with other constraints.
                 Bool if init == InitKind::Uninit => {
-                    Some((format!("Booleans must be `true` or `false`"), None))
+                    Some((format!("booleans must be either `true` or `false`"), None))
                 }
                 Char if init == InitKind::Uninit => {
-                    Some((format!("Characters must be a valid unicode codepoint"), None))
+                    Some((format!("characters must be a valid Unicode codepoint"), None))
                 }
                 // Recurse and checks for some compound types.
                 Adt(adt_def, substs) if !adt_def.is_union() => {

src/librustc_mir/borrow_check/nll.rs

@@ -360,7 +360,7 @@ pub(super) fn dump_annotation<'a, 'tcx>(
     // better.
 
     if let Some(closure_region_requirements) = closure_region_requirements {
-        let mut err = tcx.sess.diagnostic().span_note_diag(body.span, "External requirements");
+        let mut err = tcx.sess.diagnostic().span_note_diag(body.span, "external requirements");
 
         regioncx.annotate(tcx, &mut err);
 
@@ -379,7 +379,7 @@ pub(super) fn dump_annotation<'a, 'tcx>(
 
         err.buffer(errors_buffer);
     } else {
-        let mut err = tcx.sess.diagnostic().span_note_diag(body.span, "No external requirements");
+        let mut err = tcx.sess.diagnostic().span_note_diag(body.span, "no external requirements");
         regioncx.annotate(tcx, &mut err);
 
         err.buffer(errors_buffer);

src/librustc_typeck/check/cast.rs

@@ -381,7 +381,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
                     if unknown_cast_to { "to" } else { "from" }
                 );
                 err.note(
-                    "The type information given here is insufficient to check whether \
+                    "the type information given here is insufficient to check whether \
                           the pointer cast is valid",
                 );
                 if unknown_cast_to {

src/test/ui/anon-params-deprecated.stderr

@@ -2,7 +2,7 @@ warning: anonymous parameters are deprecated and will be removed in the next edi
   --> $DIR/anon-params-deprecated.rs:9:12
    |
 LL |     fn foo(i32);
-   |            ^^^ help: Try naming the parameter or explicitly ignoring it: `_: i32`
+   |            ^^^ help: try naming the parameter or explicitly ignoring it: `_: i32`
    |
 note: lint level defined here
   --> $DIR/anon-params-deprecated.rs:1:9
@@ -16,7 +16,7 @@ warning: anonymous parameters are deprecated and will be removed in the next edi
   --> $DIR/anon-params-deprecated.rs:12:30
    |
 LL |     fn bar_with_default_impl(String, String) {}
-   |                              ^^^^^^ help: Try naming the parameter or explicitly ignoring it: `_: String`
+   |                              ^^^^^^ help: try naming the parameter or explicitly ignoring it: `_: String`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue #41686 <https://github.com/rust-lang/rust/issues/41686>
@@ -25,7 +25,7 @@ warning: anonymous parameters are deprecated and will be removed in the next edi
   --> $DIR/anon-params-deprecated.rs:12:38
    |
 LL |     fn bar_with_default_impl(String, String) {}
-   |                                      ^^^^^^ help: Try naming the parameter or explicitly ignoring it: `_: String`
+   |                                      ^^^^^^ help: try naming the parameter or explicitly ignoring it: `_: String`
    |
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in the 2018 edition!
    = note: for more information, see issue #41686 <https://github.com/rust-lang/rust/issues/41686>

src/test/ui/consts/const-eval/validate_uninhabited_zsts.stderr

@@ -34,7 +34,7 @@ LL |     unsafe { std::mem::transmute(()) }
    |              help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
    |
    = note: `#[warn(invalid_value)]` on by default
-   = note: The never type (`!`) has no valid value
+   = note: the `!` type has no valid value
 
 warning: the type `Empty` does not permit zero-initialization
   --> $DIR/validate_uninhabited_zsts.rs:17:35

src/test/ui/feature-gates/feature-gate-never_type.stderr

@@ -1,4 +1,4 @@
-error[E0658]: The `!` type is experimental
+error[E0658]: the `!` type is experimental
   --> $DIR/feature-gate-never_type.rs:7:17
    |
 LL | type Ma = (u32, !, i32);
@@ -7,7 +7,7 @@ LL | type Ma = (u32, !, i32);
    = note: for more information, see https://github.com/rust-lang/rust/issues/35121
    = help: add `#![feature(never_type)]` to the crate attributes to enable
 
-error[E0658]: The `!` type is experimental
+error[E0658]: the `!` type is experimental
   --> $DIR/feature-gate-never_type.rs:8:20
    |
 LL | type Meeshka = Vec<!>;
@@ -16,7 +16,7 @@ LL | type Meeshka = Vec<!>;
    = note: for more information, see https://github.com/rust-lang/rust/issues/35121
    = help: add `#![feature(never_type)]` to the crate attributes to enable
 
-error[E0658]: The `!` type is experimental
+error[E0658]: the `!` type is experimental
   --> $DIR/feature-gate-never_type.rs:9:24
    |
 LL | type Mow = &'static fn(!) -> !;
@@ -25,7 +25,7 @@ LL | type Mow = &'static fn(!) -> !;
    = note: for more information, see https://github.com/rust-lang/rust/issues/35121
    = help: add `#![feature(never_type)]` to the crate attributes to enable
 
-error[E0658]: The `!` type is experimental
+error[E0658]: the `!` type is experimental
   --> $DIR/feature-gate-never_type.rs:10:27
    |
 LL | type Skwoz = &'static mut !;
@@ -34,7 +34,7 @@ LL | type Skwoz = &'static mut !;
    = note: for more information, see https://github.com/rust-lang/rust/issues/35121
    = help: add `#![feature(never_type)]` to the crate attributes to enable
 
-error[E0658]: The `!` type is experimental
+error[E0658]: the `!` type is experimental
   --> $DIR/feature-gate-never_type.rs:13:16
    |
 LL |     type Wub = !;

src/test/ui/future-incompatible-lint-group.stderr

@@ -2,7 +2,7 @@ error: anonymous parameters are deprecated and will be removed in the next editi
   --> $DIR/future-incompatible-lint-group.rs:4:10
    |
 LL |     fn f(u8) {}
-   |          ^^ help: Try naming the parameter or explicitly ignoring it: `_: u8`
+   |          ^^ help: try naming the parameter or explicitly ignoring it: `_: u8`
    |
 note: lint level defined here
   --> $DIR/future-incompatible-lint-group.rs:1:9

src/test/ui/issues/issue-45730.stderr

@@ -6,7 +6,7 @@ LL |     let x: *const _ = 0 as _;
    |                            |
    |                            help: consider giving more type information
    |
-   = note: The type information given here is insufficient to check whether the pointer cast is valid
+   = note: the type information given here is insufficient to check whether the pointer cast is valid
 
 error[E0641]: cannot cast to a pointer of an unknown kind
   --> $DIR/issue-45730.rs:5:23
@@ -16,7 +16,7 @@ LL |     let x: *const _ = 0 as *const _;
    |                            |
    |                            help: consider giving more type information
    |
-   = note: The type information given here is insufficient to check whether the pointer cast is valid
+   = note: the type information given here is insufficient to check whether the pointer cast is valid
 
 error[E0641]: cannot cast to a pointer of an unknown kind
   --> $DIR/issue-45730.rs:8:13
@@ -26,7 +26,7 @@ LL |     let x = 0 as *const i32 as *const _ as *mut _;
    |                                            |
    |                                            help: consider giving more type information
    |
-   = note: The type information given here is insufficient to check whether the pointer cast is valid
+   = note: the type information given here is insufficient to check whether the pointer cast is valid
 
 error: aborting due to 3 previous errors