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

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 `{}`.",

src/librustc_resolve/build_reduced_graph.rs

@@ -963,7 +963,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
                             .session
                             .struct_span_err(
                                 attr.span,
-                                "`macro_use` is not supported on `extern crate self`",
+                                "`#[macro_use]` is not supported on `extern crate self`",
                             )
                             .emit();
                     }
@@ -1054,10 +1054,10 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
     fn contains_macro_use(&mut self, attrs: &[ast::Attribute]) -> bool {
         for attr in attrs {
             if attr.check_name(sym::macro_escape) {
-                let msg = "macro_escape is a deprecated synonym for macro_use";
+                let msg = "`#[macro_escape]` is a deprecated synonym for `#[macro_use]`";
                 let mut err = self.r.session.struct_span_warn(attr.span, msg);
                 if let ast::AttrStyle::Inner = attr.style {
-                    err.help("consider an outer attribute, `#[macro_use]` mod ...").emit();
+                    err.help("try an outer attribute: `#[macro_use]`").emit();
                 } else {
                     err.emit();
                 }
@@ -1066,7 +1066,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
             }
 
             if !attr.is_word() {
-                self.r.session.span_err(attr.span, "arguments to macro_use are not allowed here");
+                self.r.session.span_err(attr.span, "arguments to `macro_use` are not allowed here");
             }
             return true;
         }

src/librustc_resolve/lib.rs

@@ -2006,7 +2006,7 @@ impl<'a> Resolver<'a> {
                             continue;
                         }
                     }
-                    let msg = "there are too many initial `super`s.".to_string();
+                    let msg = "there are too many leading `super` keywords".to_string();
                     return PathResult::Failed {
                         span: ident.span,
                         label: msg,

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/librustc_typeck/check/method/suggest.rs

@@ -479,7 +479,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     macro_rules! report_function {
                         ($span:expr, $name:expr) => {
                             err.note(&format!(
-                                "{} is a function, perhaps you wish to call it",
+                                "`{}` is a function, perhaps you wish to call it",
                                 $name
                             ));
                         };

src/librustc_typeck/check/mod.rs

@@ -1664,7 +1664,7 @@ fn check_opaque_for_cycles<'tcx>(
         if let hir::OpaqueTyOrigin::AsyncFn = origin {
             struct_span_err!(tcx.sess, span, E0733, "recursion in an `async fn` requires boxing",)
                 .span_label(span, "recursive `async fn`")
-                .note("a recursive `async fn` must be rewritten to return a boxed `dyn Future`.")
+                .note("a recursive `async fn` must be rewritten to return a boxed `dyn Future`")
                 .emit();
         } else {
             let mut err =

src/libstd/panicking.rs

@@ -199,7 +199,7 @@ fn default_hook(info: &PanicInfo<'_>) {
                     let _ = writeln!(
                         err,
                         "note: run with `RUST_BACKTRACE=1` \
-                                           environment variable to display a backtrace."
+                                           environment variable to display a backtrace"
                     );
                 }
             }

src/test/compile-fail/panic-handler-twice.rs

@@ -10,7 +10,7 @@ use core::panic::PanicInfo;
 
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
-    //~^ error duplicate lang item found: `panic_impl`
+    //~^ ERROR found duplicate lang item `panic_impl`
     loop {}
 }
 

src/test/run-make-fulldeps/libtest-json/output-default.json

@@ -2,7 +2,7 @@
 { "type": "test", "event": "started", "name": "a" }
 { "type": "test", "name": "a", "event": "ok" }
 { "type": "test", "event": "started", "name": "b" }
-{ "type": "test", "name": "b", "event": "failed", "stdout": "thread 'main' panicked at 'assertion failed: false', f.rs:9:5\nnote: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.\n" }
+{ "type": "test", "name": "b", "event": "failed", "stdout": "thread 'main' panicked at 'assertion failed: false', f.rs:9:5\nnote: run with `RUST_BACKTRACE=1` environment variable to display a backtrace\n" }
 { "type": "test", "event": "started", "name": "c" }
 { "type": "test", "name": "c", "event": "ok" }
 { "type": "test", "event": "started", "name": "d" }

src/test/run-make-fulldeps/libtest-json/output-stdout-success.json

@@ -2,7 +2,7 @@
 { "type": "test", "event": "started", "name": "a" }
 { "type": "test", "name": "a", "event": "ok", "stdout": "print from successful test\n" }
 { "type": "test", "event": "started", "name": "b" }
-{ "type": "test", "name": "b", "event": "failed", "stdout": "thread 'main' panicked at 'assertion failed: false', f.rs:9:5\nnote: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.\n" }
+{ "type": "test", "name": "b", "event": "failed", "stdout": "thread 'main' panicked at 'assertion failed: false', f.rs:9:5\nnote: run with `RUST_BACKTRACE=1` environment variable to display a backtrace\n" }
 { "type": "test", "event": "started", "name": "c" }
 { "type": "test", "name": "c", "event": "ok", "stdout": "thread 'main' panicked at 'assertion failed: false', f.rs:15:5\n" }
 { "type": "test", "event": "started", "name": "d" }

src/test/rustdoc-ui/failed-doctest-output.stdout

@@ -27,7 +27,7 @@ stderr:
 stderr 1
 stderr 2
 thread 'main' panicked at 'oh no', $DIR/failed-doctest-output.rs:7:1
-note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
 
 

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/async-await/mutually-recursive-async-impl-trait-type.stderr

@@ -4,15 +4,15 @@ error[E0733]: recursion in an `async fn` requires boxing
 LL | async fn rec_1() {
    |                  ^ recursive `async fn`
    |
-   = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`.
+   = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`
 
 error[E0733]: recursion in an `async fn` requires boxing
   --> $DIR/mutually-recursive-async-impl-trait-type.rs:9:18
    |
 LL | async fn rec_2() {
    |                  ^ recursive `async fn`
    |
-   = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`.
+   = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`
 
 error: aborting due to 2 previous errors
 

src/test/ui/async-await/recursive-async-impl-trait-type.stderr

@@ -4,7 +4,7 @@ error[E0733]: recursion in an `async fn` requires boxing
 LL | async fn recursive_async_function() -> () {
    |                                        ^^ recursive `async fn`
    |
-   = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`.
+   = note: a recursive `async fn` must be rewritten to return a boxed `dyn Future`
 
 error: aborting due to previous error
 

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
@@ -45,7 +45,7 @@ LL | const BAR: [Empty; 3] = [unsafe { std::mem::transmute(()) }; 3];
    |                                   this code causes undefined behavior when executed
    |                                   help: use `MaybeUninit<T>` instead, and only call `assume_init` after initialization is done
    |
-   = note: 0-variant enums have no valid value
+   = note: enums with no variants have no valid value
 
 error: aborting due to previous error
 

src/test/ui/consts/miri_unleashed/mutable_const2.stderr

@@ -11,7 +11,7 @@ LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *m
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:346:17
-note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
 error: internal compiler error: unexpected panic