tests: add test that roughly ensures that our lint messages conform with the diagnostics convention of the rustc dev guide

Cargo.toml

@@ -42,6 +42,7 @@ tester = "0.9"
 clippy-mini-macro-test = { version = "0.2", path = "mini-macro" }
 serde = { version = "1.0", features = ["derive"] }
 derive-new = "0.5"
+regex = "1.4"
 
 # A noop dependency that changes in the Rust repository, it's a bit of a hack.
 # See the `src/tools/rustc-workspace-hack/README.md` file in `rust-lang/rust`

clippy_lints/src/assign_ops.rs

@@ -209,7 +209,7 @@ fn lint_misrefactored_assign_op(
                 diag.span_suggestion(
                     expr.span,
                     &format!(
-                        "Did you mean `{} = {} {} {}` or `{}`? Consider replacing it with",
+                        "did you mean `{} = {} {} {}` or `{}`? Consider replacing it with",
                         snip_a,
                         snip_a,
                         op.node.as_str(),

clippy_lints/src/attrs.rs

@@ -639,7 +639,7 @@ fn check_mismatched_target_os(cx: &EarlyContext<'_>, attr: &Attribute) {
                     diag.span_suggestion(span, "try", sugg, Applicability::MaybeIncorrect);
 
                     if !unix_suggested && is_unix(os) {
-                        diag.help("Did you mean `unix`?");
+                        diag.help("did you mean `unix`?");
                         unix_suggested = true;
                     }
                 }

clippy_lints/src/await_holding_invalid.rs

@@ -116,7 +116,7 @@ fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorType
                     cx,
                     AWAIT_HOLDING_LOCK,
                     ty_cause.span,
-                    "this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await.",
+                    "this MutexGuard is held across an 'await' point. Consider using an async-aware Mutex type or ensuring the MutexGuard is dropped before calling await",
                     ty_cause.scope_span.or(Some(span)),
                     "these are all the await points this lock is held through",
                 );
@@ -126,7 +126,7 @@ fn check_interior_types(cx: &LateContext<'_>, ty_causes: &[GeneratorInteriorType
                         cx,
                         AWAIT_HOLDING_REFCELL_REF,
                         ty_cause.span,
-                        "this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await.",
+                        "this RefCell Ref is held across an 'await' point. Consider ensuring the Ref is dropped before calling await",
                         ty_cause.scope_span.or(Some(span)),
                         "these are all the await points this ref is held through",
                     );

clippy_lints/src/comparison_chain.rs

@@ -117,7 +117,7 @@ impl<'tcx> LateLintPass<'tcx> for ComparisonChain {
             expr.span,
             "`if` chain can be rewritten with `match`",
             None,
-            "Consider rewriting the `if` chain to use `cmp` and `match`.",
+            "consider rewriting the `if` chain to use `cmp` and `match`",
         )
     }
 }

clippy_lints/src/drop_forget_ref.rs

@@ -98,13 +98,13 @@ declare_clippy_lint! {
 }
 
 const DROP_REF_SUMMARY: &str = "calls to `std::mem::drop` with a reference instead of an owned value. \
-                                Dropping a reference does nothing.";
+                                Dropping a reference does nothing";
 const FORGET_REF_SUMMARY: &str = "calls to `std::mem::forget` with a reference instead of an owned value. \
-                                  Forgetting a reference does nothing.";
+                                  Forgetting a reference does nothing";
 const DROP_COPY_SUMMARY: &str = "calls to `std::mem::drop` with a value that implements `Copy`. \
-                                 Dropping a copy leaves the original intact.";
+                                 Dropping a copy leaves the original intact";
 const FORGET_COPY_SUMMARY: &str = "calls to `std::mem::forget` with a value that implements `Copy`. \
-                                   Forgetting a copy leaves the original intact.";
+                                   Forgetting a copy leaves the original intact";
 
 declare_lint_pass!(DropForgetRef => [DROP_REF, FORGET_REF, DROP_COPY, FORGET_COPY]);
 

clippy_lints/src/fallible_impl_from.rs

@@ -133,7 +133,7 @@ fn lint_impl_body<'tcx>(cx: &LateContext<'tcx>, impl_span: Span, impl_items: &[h
                         move |diag| {
                             diag.help(
                                 "`From` is intended for infallible conversions only. \
-                                Use `TryFrom` if there's a possibility for the conversion to fail.");
+                                Use `TryFrom` if there's a possibility for the conversion to fail");
                             diag.span_note(fpu.result, "potential failure(s)");
                         });
                 }

clippy_lints/src/indexing_slicing.rs

@@ -132,13 +132,13 @@ impl<'tcx> LateLintPass<'tcx> for IndexingSlicing {
                 }
 
                 let help_msg = match (range.start, range.end) {
-                    (None, Some(_)) => "Consider using `.get(..n)`or `.get_mut(..n)` instead",
-                    (Some(_), None) => "Consider using `.get(n..)` or .get_mut(n..)` instead",
-                    (Some(_), Some(_)) => "Consider using `.get(n..m)` or `.get_mut(n..m)` instead",
+                    (None, Some(_)) => "consider using `.get(..n)`or `.get_mut(..n)` instead",
+                    (Some(_), None) => "consider using `.get(n..)` or .get_mut(n..)` instead",
+                    (Some(_), Some(_)) => "consider using `.get(n..m)` or `.get_mut(n..m)` instead",
                     (None, None) => return, // [..] is ok.
                 };
 
-                span_lint_and_help(cx, INDEXING_SLICING, expr.span, "slicing may panic.", None, help_msg);
+                span_lint_and_help(cx, INDEXING_SLICING, expr.span, "slicing may panic", None, help_msg);
             } else {
                 // Catchall non-range index, i.e., [n] or [n << m]
                 if let ty::Array(..) = ty.kind() {
@@ -153,9 +153,9 @@ impl<'tcx> LateLintPass<'tcx> for IndexingSlicing {
                     cx,
                     INDEXING_SLICING,
                     expr.span,
-                    "indexing may panic.",
+                    "indexing may panic",
                     None,
-                    "Consider using `.get(n)` or `.get_mut(n)` instead",
+                    "consider using `.get(n)` or `.get_mut(n)` instead",
                 );
             }
         }

clippy_lints/src/integer_division.rs

@@ -39,7 +39,7 @@ impl<'tcx> LateLintPass<'tcx> for IntegerDivision {
                 expr.span,
                 "integer division",
                 None,
-                "division of integers may cause loss of precision. consider using floats.",
+                "division of integers may cause loss of precision. consider using floats",
             );
         }
     }

clippy_lints/src/loops.rs

@@ -1625,10 +1625,7 @@ fn check_for_loop_range<'tcx>(
                         cx,
                         NEEDLESS_RANGE_LOOP,
                         expr.span,
-                        &format!(
-                            "the loop variable `{}` is only used to index `{}`.",
-                            ident.name, indexed
-                        ),
+                        &format!("the loop variable `{}` is only used to index `{}`", ident.name, indexed),
                         |diag| {
                             multispan_sugg(
                                 diag,
@@ -1763,7 +1760,7 @@ fn check_arg_type(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>) {
             arg.span,
             &format!(
                 "for loop over `{0}`, which is an `Option`. This is more readably written as an \
-                `if let` statement.",
+                `if let` statement",
                 snippet(cx, arg.span, "_")
             ),
             None,
@@ -1780,7 +1777,7 @@ fn check_arg_type(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>) {
             arg.span,
             &format!(
                 "for loop over `{0}`, which is a `Result`. This is more readably written as an \
-                `if let` statement.",
+                `if let` statement",
                 snippet(cx, arg.span, "_")
             ),
             None,
@@ -1826,7 +1823,7 @@ fn check_for_loop_explicit_counter<'tcx>(
                         cx,
                         EXPLICIT_COUNTER_LOOP,
                         for_span.with_hi(arg.span.hi()),
-                        &format!("the variable `{}` is used as a loop counter.", name),
+                        &format!("the variable `{}` is used as a loop counter", name),
                         "consider using",
                         format!(
                             "for ({}, {}) in {}.enumerate()",
@@ -3055,16 +3052,16 @@ impl IterFunction {
     fn get_suggestion_text(&self) -> &'static str {
         match &self.func {
             IterFunctionKind::IntoIter => {
-                "Use the original Iterator instead of collecting it and then producing a new one"
+                "use the original Iterator instead of collecting it and then producing a new one"
             },
             IterFunctionKind::Len => {
-                "Take the original Iterator's count instead of collecting it and finding the length"
+                "take the original Iterator's count instead of collecting it and finding the length"
             },
             IterFunctionKind::IsEmpty => {
-                "Check if the original Iterator has anything instead of collecting it and seeing if it's empty"
+                "check if the original Iterator has anything instead of collecting it and seeing if it's empty"
             },
             IterFunctionKind::Contains(_) => {
-                "Check if the original Iterator contains an element instead of collecting then checking"
+                "check if the original Iterator contains an element instead of collecting then checking"
             },
         }
     }

clippy_lints/src/matches.rs

@@ -1173,9 +1173,9 @@ fn check_wild_in_or_pats(cx: &LateContext<'_>, arms: &[Arm<'_>]) {
                     cx,
                     WILDCARD_IN_OR_PATTERNS,
                     arm.pat.span,
-                    "wildcard pattern covers any other pattern as it will match anyway.",
+                    "wildcard pattern covers any other pattern as it will match anyway",
                     None,
-                    "Consider handling `_` separately.",
+                    "consider handling `_` separately",
                 );
             }
         }

clippy_lints/src/methods/mod.rs

@@ -2569,7 +2569,7 @@ fn lint_step_by<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>, args: &'tcx
                 cx,
                 ITERATOR_STEP_BY_ZERO,
                 expr.span,
-                "Iterator::step_by(0) will panic at runtime",
+                "`Iterator::step_by(0)` will panic at runtime",
             );
         }
     }
@@ -3081,7 +3081,7 @@ fn lint_filter_next<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, fil
     // lint if caller of `.filter().next()` is an Iterator
     if match_trait_method(cx, expr, &paths::ITERATOR) {
         let msg = "called `filter(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
-                   `.find(..)` instead.";
+                   `.find(..)` instead";
         let filter_snippet = snippet(cx, filter_args[1].span, "..");
         if filter_snippet.lines().count() <= 1 {
             let iter_snippet = snippet(cx, filter_args[0].span, "..");
@@ -3209,7 +3209,7 @@ fn lint_filter_map_next<'tcx>(
         }
 
         let msg = "called `filter_map(..).next()` on an `Iterator`. This is more succinctly expressed by calling \
-                   `.find_map(..)` instead.";
+                   `.find_map(..)` instead";
         let filter_snippet = snippet(cx, filter_args[1].span, "..");
         if filter_snippet.lines().count() <= 1 {
             let iter_snippet = snippet(cx, filter_args[0].span, "..");

clippy_lints/src/methods/unnecessary_lazy_eval.rs

@@ -50,7 +50,7 @@ pub(super) fn lint<'tcx>(
                     UNNECESSARY_LAZY_EVALUATIONS,
                     expr.span,
                     msg,
-                    &format!("Use `{}` instead", simplify_using),
+                    &format!("use `{}` instead", simplify_using),
                     format!(
                         "{0}.{1}({2})",
                         snippet(cx, args[0].span, ".."),

clippy_lints/src/misc.rs

@@ -292,7 +292,7 @@ impl<'tcx> LateLintPass<'tcx> for MiscLints {
                     TOPLEVEL_REF_ARG,
                     arg.pat.span,
                     "`ref` directly on a function argument is ignored. \
-                    Consider using a reference type instead.",
+                    Consider using a reference type instead",
                 );
             }
         }
@@ -422,7 +422,7 @@ impl<'tcx> LateLintPass<'tcx> for MiscLints {
                 expr.span,
                 &format!(
                     "used binding `{}` which is prefixed with an underscore. A leading \
-                     underscore signals that a binding will not be used.",
+                     underscore signals that a binding will not be used",
                     binding
                 ),
             );

clippy_lints/src/needless_question_mark.rs

@@ -142,7 +142,7 @@ fn emit_lint(cx: &LateContext<'_>, expr: &SomeOkCall<'_>) {
         cx,
         NEEDLESS_QUESTION_MARK,
         entire_expr.span,
-        "Question mark operator is useless here",
+        "question mark operator is useless here",
         "try",
         format!("{}", utils::snippet(cx, inner_expr.span, r#""...""#)),
         Applicability::MachineApplicable,

clippy_lints/src/ptr.rs

@@ -188,7 +188,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
                         PTR_ARG,
                         arg.span,
                         "writing `&Vec<_>` instead of `&[_]` involves one more reference and cannot be used \
-                         with non-Vec-based slices.",
+                         with non-Vec-based slices",
                         |diag| {
                             if let Some(ref snippet) = get_only_generic_arg_snippet(cx, arg) {
                                 diag.span_suggestion(
@@ -217,7 +217,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
                         cx,
                         PTR_ARG,
                         arg.span,
-                        "writing `&String` instead of `&str` involves a new object where a slice will do.",
+                        "writing `&String` instead of `&str` involves a new object where a slice will do",
                         |diag| {
                             diag.span_suggestion(arg.span, "change this to", "&str".into(), Applicability::Unspecified);
                             for (clonespan, suggestion) in spans {
@@ -239,7 +239,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
                         cx,
                         PTR_ARG,
                         arg.span,
-                        "writing `&PathBuf` instead of `&Path` involves a new object where a slice will do.",
+                        "writing `&PathBuf` instead of `&Path` involves a new object where a slice will do",
                         |diag| {
                             diag.span_suggestion(
                                 arg.span,
@@ -278,7 +278,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
                                 cx,
                                 PTR_ARG,
                                 arg.span,
-                                "using a reference to `Cow` is not recommended.",
+                                "using a reference to `Cow` is not recommended",
                                 "change this to",
                                 "&".to_owned() + &r,
                                 Applicability::Unspecified,

clippy_lints/src/suspicious_operation_groupings.rs

@@ -261,8 +261,8 @@ fn emit_suggestion(cx: &EarlyContext<'_>, span: Span, sugg: String, applicabilit
         cx,
         SUSPICIOUS_OPERATION_GROUPINGS,
         span,
-        "This sequence of operators looks suspiciously like a bug.",
-        "I think you meant",
+        "this sequence of operators looks suspiciously like a bug",
+        "did you mean",
         sugg,
         applicability,
     )

clippy_lints/src/transmuting_null.rs

@@ -27,7 +27,7 @@ declare_clippy_lint! {
 
 declare_lint_pass!(TransmutingNull => [TRANSMUTING_NULL]);
 
-const LINT_MSG: &str = "transmuting a known null pointer into a reference.";
+const LINT_MSG: &str = "transmuting a known null pointer into a reference";
 
 impl<'tcx> LateLintPass<'tcx> for TransmutingNull {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {

clippy_lints/src/types.rs

@@ -388,7 +388,7 @@ impl Types {
                                 hir_ty.span,
                                 "you seem to be trying to use `Box<Vec<T>>`. Consider using just `Vec<T>`",
                                 None,
-                                "`Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation.",
+                                "`Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation",
                             );
                             return; // don't recurse into the type
                         }
@@ -554,7 +554,7 @@ impl Types {
                                     cx,
                                     VEC_BOX,
                                     hir_ty.span,
-                                    "`Vec<T>` is already on the heap, the boxing is unnecessary.",
+                                    "`Vec<T>` is already on the heap, the boxing is unnecessary",
                                     "try",
                                     format!("Vec<{}>", snippet(cx, boxed_ty.span, "..")),
                                     Applicability::MachineApplicable,
@@ -578,7 +578,7 @@ impl Types {
                             cx,
                             LINKEDLIST,
                             hir_ty.span,
-                            "I see you're using a LinkedList! Perhaps you meant some other data structure?",
+                            "you seem to be using a `LinkedList`! Perhaps you meant some other data structure?",
                             None,
                             "a `VecDeque` might work",
                         );

clippy_lints/src/zero_div_zero.rs

@@ -55,7 +55,7 @@ impl<'tcx> LateLintPass<'tcx> for ZeroDiv {
                     "constant division of `0.0` with `0.0` will always result in NaN",
                     None,
                     &format!(
-                        "Consider using `{}::NAN` if you would like a constant representing NaN",
+                        "consider using `{}::NAN` if you would like a constant representing NaN",
                         float_type,
                     ),
                 );