Rollup merge of rust-lang#68096 - varkor:diagnostic-cleanup, r=Centril

Clean up some diagnostics by making them more consistent

In general:

- Diagnostic should start with a lowercase letter.
- Diagnostics should not end with a full stop.
- Ellipses contain three dots.
- Backticks should encode Rust code.

I also reworded a couple of messages to make them read more clearly.

It might be sensible to create a style guide for diagnostics, so these informal conventions are written down somewhere, after which we could audit the existing diagnostics.

r? @Centril

Author: Dylan-DPC

src/libcore/lib.rs

@@ -44,7 +44,7 @@
 // Here we explicitly #[cfg]-out this whole crate when testing. If we don't do
 // this, both the generated test artifact and the linked libtest (which
 // transitively includes libcore) will both define the same set of lang items,
-// and this will cause the E0152 "duplicate lang item found" error. See
+// and this will cause the E0152 "found duplicate lang item" error. See
 // discussion in #50466 for details.
 //
 // This cfg won't affect doc tests.

src/librustc/middle/lang_items.rs

@@ -184,7 +184,7 @@ impl LanguageItemCollector<'tcx> {
                         self.tcx.sess,
                         span,
                         E0152,
-                        "duplicate lang item found: `{}`.",
+                        "found duplicate lang item `{}`",
                         name
                     ),
                     None => {
@@ -206,12 +206,12 @@ impl LanguageItemCollector<'tcx> {
                     },
                 };
                 if let Some(span) = self.tcx.hir().span_if_local(original_def_id) {
-                    err.span_note(span, "first defined here.");
+                    err.span_note(span, "first defined here");
                 } else {
                     match self.tcx.extern_crate(original_def_id) {
                         Some(ExternCrate {dependency_of, ..}) => {
                             err.note(&format!(
-                            "first defined in crate `{}` (which `{}` depends on).",
+                            "first defined in crate `{}` (which `{}` depends on)",
                                       self.tcx.crate_name(original_def_id.krate),
                                       self.tcx.crate_name(*dependency_of)));
                         },

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() => {
@@ -1959,21 +1959,24 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidValue {
                         // return `Bound::Excluded`.  (And we have tests checking that we
                         // handle the attribute correctly.)
                         (Bound::Included(lo), _) if lo > 0 => {
-                            return Some((format!("{} must be non-null", ty), None));
+                            return Some((format!("`{}` must be non-null", ty), None));
                         }
                         (Bound::Included(_), _) | (_, Bound::Included(_))
                             if init == InitKind::Uninit =>
                         {
                             return Some((
-                                format!("{} must be initialized inside its custom valid range", ty),
+                                format!(
+                                    "`{}` must be initialized inside its custom valid range",
+                                    ty,
+                                ),
                                 None,
                             ));
                         }
                         _ => {}
                     }
                     // Now, recurse.
                     match adt_def.variants.len() {
-                        0 => Some((format!("0-variant enums have no valid value"), None)),
+                        0 => Some((format!("enums with no variants have no valid value"), None)),
                         1 => {
                             // Struct, or enum with exactly one variant.
                             // Proceed recursively, check all fields.

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_parse/parser/attr.rs

@@ -236,8 +236,8 @@ impl<'a> Parser<'a> {
             self.struct_span_err(lit.span, msg)
                 .help(
                     "instead of using a suffixed literal \
-                                    (1u8, 1.0f32, etc.), use an unsuffixed version \
-                                    (1, 1.0, etc.).",
+                                    (`1u8`, `1.0f32`, etc.), use an unsuffixed version \
+                                    (`1`, `1.0`, etc.)",
                 )
                 .emit()
         }

src/librustc_parse/parser/pat.rs

@@ -209,13 +209,13 @@ impl<'a> Parser<'a> {
         if let Ok(seq_snippet) = self.span_to_snippet(seq_span) {
             err.span_suggestion(
                 seq_span,
-                "try adding parentheses to match on a tuple..",
+                "try adding parentheses to match on a tuple...",
                 format!("({})", seq_snippet),
                 Applicability::MachineApplicable,
             )
             .span_suggestion(
                 seq_span,
-                "..or a vertical bar to match on multiple alternatives",
+                "...or a vertical bar to match on multiple alternatives",
                 format!("{}", seq_snippet.replace(",", " |")),
                 Applicability::MachineApplicable,
             );

src/librustc_passes/diagnostic_items.rs

@@ -73,7 +73,7 @@ fn collect_item(
                 )),
             };
             if let Some(span) = tcx.hir().span_if_local(original_def_id) {
-                err.span_note(span, "first defined here.");
+                err.span_note(span, "first defined here");
             } else {
                 err.note(&format!(
                     "first defined in crate `{}`.",