Polish linter diagnostics (#285)

This makes a few small improvements to the diagnostics of the linter so
they're simpler, clearer, and more consistent. If you're reviewing, I
recommend going through each commit individually!

Part of #284.

bevy_lint/src/lints/borrowed_reborrowable.rs

@@ -99,9 +99,9 @@
 use std::ops::ControlFlow;
 
 use crate::{declare_bevy_lint, declare_bevy_lint_pass};
-use clippy_utils::{diagnostics::span_lint_and_sugg, ty::match_type};
+use clippy_utils::{diagnostics::span_lint_and_sugg, source::snippet_opt, ty::match_type};
 use rustc_errors::Applicability;
-use rustc_hir::{Body, FnDecl, Mutability, intravisit::FnKind};
+use rustc_hir::{Body, FnDecl, MutTy, Mutability, intravisit::FnKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::{Interner, Ty, TyKind, TypeVisitable, TypeVisitor};
 use rustc_span::{
@@ -113,7 +113,7 @@ use rustc_span::{
 declare_bevy_lint! {
     pub BORROWED_REBORROWABLE,
     PEDANTIC,
-    "parameter takes a mutable reference to a re-borrowable type",
+    "function parameter takes a mutable reference to a re-borrowable type",
 }
 
 declare_bevy_lint_pass! {
@@ -184,13 +184,31 @@ impl<'tcx> LateLintPass<'tcx> for BorrowedReborrowable {
 
             let span = decl.inputs[arg_index].span.to(arg_ident.span);
 
+            // This tries to get the user-written form of `T` given the HIR representation for `&T`
+            // / `&mut T`. If we cannot for whatever reason, we fallback to using
+            // `Ty::to_string()` to get the fully-qualified form of `T`.
+            //
+            // For example, given a function signature like `fn(&mut Commands)`, we try to get the
+            // snippet for just `Commands` but default to `bevy::prelude::Commands<'_, '_>` if we
+            // cannot.
+            let ty_snippet = match decl.inputs[arg_index].kind {
+                // The `Ty` should be a `Ref`, since we proved that above.
+                rustc_hir::TyKind::Ref(_, MutTy { ty: inner_ty, .. }) => {
+                    // Get the snippet for the inner type.
+                    snippet_opt(cx, inner_ty.span)
+                }
+                // If it's not a `Ref` for whatever reason, fallback to our default value.
+                _ => None,
+            }
+            .unwrap_or_else(|| ty.to_string());
+
             span_lint_and_sugg(
                 cx,
                 BORROWED_REBORROWABLE.lint,
                 span,
                 reborrowable.message(),
                 reborrowable.help(),
-                reborrowable.suggest(arg_ident, ty.to_string()),
+                reborrowable.suggest(arg_ident, ty_snippet),
                 // Not machine-applicable since the function body may need to
                 // also be updated to account for the removed ref
                 Applicability::MaybeIncorrect,

bevy_lint/src/lints/cargo/duplicate_bevy_dependencies.rs

@@ -167,14 +167,11 @@ fn lint_with_target_version(
                 cx,
                 DUPLICATE_BEVY_DEPENDENCIES.lint,
                 toml_span(cargo_toml_reference.span(), file),
-                format!(
-                    "Mismatching versions of `bevy` found, {} used bevy version {}",
-                    mismatching_dependency.0, mismatching_dependency.1
-                ),
+                DUPLICATE_BEVY_DEPENDENCIES.lint.desc,
                 |diag| {
                     diag.span_help(
                         bevy_cargo_toml_span,
-                        format!("Expected all crates to use `bevy` {target_version}"),
+                        format!("expected all crates to use `bevy` {target_version}, but `{}` uses `bevy` {}", mismatching_dependency.0, mismatching_dependency.1),
                     );
                 },
             );

bevy_lint/src/lints/insert_event_resource.rs

@@ -70,6 +70,8 @@ declare_bevy_lint_pass! {
     },
 }
 
+const HELP_MESSAGE: &str = "inserting an `Events` resource does not fully setup that event";
+
 impl<'tcx> LateLintPass<'tcx> for InsertEventResource {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
         // Find a method call.
@@ -128,7 +130,7 @@ fn check_insert_resource(cx: &LateContext<'_>, method_call: &MethodCall) {
                 format!(
                     "called `App::insert_resource{generics_snippet}({receiver_snippet}, {args_snippet})` instead of `App::add_event::<{event_ty_snippet}>({receiver_snippet})`"
                 ),
-                "inserting an `Events` resource does not fully setup that event",
+                HELP_MESSAGE,
                 format!("App::add_event::<{event_ty_snippet}>({receiver_snippet})"),
                 applicability,
             );
@@ -140,7 +142,7 @@ fn check_insert_resource(cx: &LateContext<'_>, method_call: &MethodCall) {
                 format!(
                     "called `App::insert_resource{generics_snippet}({args_snippet})` instead of `App::add_event::<{event_ty_snippet}>()`"
                 ),
-                "inserting an `Events` resource does not fully setup that event",
+                HELP_MESSAGE,
                 format!("add_event::<{event_ty_snippet}>()"),
                 applicability,
             );
@@ -208,7 +210,7 @@ fn check_init_resource<'tcx>(cx: &LateContext<'tcx>, method_call: &MethodCall<'t
                     format!(
                         "called `App::init_resource{generics_snippet}({receiver_snippet})` instead of `App::add_event::<{event_ty_snippet}>({receiver_snippet})`"
                     ),
-                    "inserting an `Events` resource does not fully setup that event",
+                    HELP_MESSAGE,
                     format!("App::add_event::<{event_ty_snippet}>({receiver_snippet})"),
                     applicability,
                 );
@@ -220,7 +222,7 @@ fn check_init_resource<'tcx>(cx: &LateContext<'tcx>, method_call: &MethodCall<'t
                     format!(
                         "called `App::init_resource{generics_snippet}({args_snippet})` instead of `App::add_event::<{event_ty_snippet}>()`"
                     ),
-                    "inserting an `Events` resource does not fully setup that event",
+                    HELP_MESSAGE,
                     format!("add_event::<{event_ty_snippet}>()"),
                     applicability,
                 );

bevy_lint/src/lints/zst_query.rs

@@ -68,10 +68,10 @@ use rustc_middle::ty::{
 
 declare_bevy_lint! {
     pub ZST_QUERY,
-    // This will eventually be a `RESTRICTION` lint, but due to <https://github.com/TheBevyFlock/bevy_cli/issues/252>
-    // it is not yet ready for production.
+    // This will eventually be a `RESTRICTION` lint, but due to
+    // <https://github.com/TheBevyFlock/bevy_cli/issues/279> it is not yet ready for production.
     NURSERY,
-    "query for a zero-sized type",
+    "queried a zero-sized type",
 }
 
 declare_bevy_lint_pass! {
@@ -136,7 +136,11 @@ impl QueryKind {
         // In the future, we might want to span the usage site of `is_added()`/`is_changed()`
         // and suggest to use `Added<Foo>`/`Changed<Foo>` instead.
         match self {
-            Self::Query => format!("consider using a filter instead: `With<{ty}>`"),
+            Self::Query => format!(
+                // NOTE: This isn't actually true, please see #279 for more info and how this will
+                // be fixed!
+                "zero-sized types do not retrieve any data, consider using a filter instead: `With<{ty}>`"
+            ),
         }
     }
 }

bevy_lint/tests/ui-cargo/duplicate_bevy_dependencies/long_version_format/fail/Cargo.stderr

@@ -1,10 +1,10 @@
-error: Mismatching versions of `bevy` found, leafwing-input-manager used bevy version ^0.13
+error: multiple versions of the `bevy` crate found
   --> Cargo.toml:12:26
    |
 12 | leafwing-input-manager = "0.13"
    |                          ^^^^^^
    |
-help: Expected all crates to use `bevy` 0.14.2
+help: expected all crates to use `bevy` 0.14.2, but `leafwing-input-manager` uses `bevy` ^0.13
   --> Cargo.toml:11:8
    |
 11 | bevy = { version = "0.14.2" }

bevy_lint/tests/ui-cargo/duplicate_bevy_dependencies/short_version_format/fail/Cargo.stderr

@@ -1,10 +1,10 @@
-error: Mismatching versions of `bevy` found, leafwing-input-manager used bevy version ^0.13
+error: multiple versions of the `bevy` crate found
   --> Cargo.toml:12:26
    |
 12 | leafwing-input-manager = "0.13"
    |                          ^^^^^^
    |
-help: Expected all crates to use `bevy` 0.14.2
+help: expected all crates to use `bevy` 0.14.2, but `leafwing-input-manager` uses `bevy` ^0.13
   --> Cargo.toml:11:8
    |
 11 | bevy = "0.14.2"

bevy_lint/tests/ui-cargo/duplicate_bevy_dependencies/with_feature/fail/Cargo.stderr

@@ -1,10 +1,10 @@
-error: Mismatching versions of `bevy` found, leafwing-input-manager used bevy version ^0.13
+error: multiple versions of the `bevy` crate found
   --> Cargo.toml:12:26
    |
 12 | leafwing-input-manager = "0.13"
    |                          ^^^^^^
    |
-help: Expected all crates to use `bevy` 0.14.2
+help: expected all crates to use `bevy` 0.14.2, but `leafwing-input-manager` uses `bevy` ^0.13
   --> Cargo.toml:11:8
    |
 11 | bevy = { version = "0.14.2", features = ["android_shared_stdcxx"] }

bevy_lint/tests/ui/borrowed_reborrowable/closures.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut Commands` instead of a re-borrowed `Commands`
   --> tests/ui/borrowed_reborrowable/closures.rs:15:20
    |
 15 |     let closure = |commands: &mut Commands| {
-   |                    ^^^^^^^^^^^^^^^^^^^^^^^ help: use `Commands` instead: `mut commands: bevy::prelude::Commands<'_, '_>`
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^ help: use `Commands` instead: `mut commands: Commands`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/closures.rs:5:9

bevy_lint/tests/ui/borrowed_reborrowable/commands.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut Commands` instead of a re-borrowed `Commands`
   --> tests/ui/borrowed_reborrowable/commands.rs:17:22
    |
 17 | fn mutable_reference(commands: &mut Commands) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^ help: use `Commands` instead: `mut commands: bevy::prelude::Commands<'_, '_>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^ help: use `Commands` instead: `mut commands: Commands`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/commands.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut Commands` instead of a re-borrowed `Commands`
   --> tests/ui/borrowed_reborrowable/commands.rs:23:33
    |
 23 | fn mutable_reference_return<'a>(_commands: &'a mut Commands) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `Commands` instead: `mut _commands: bevy::prelude::Commands<'_, '_>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `Commands` instead: `mut _commands: Commands`
 
 error: aborting due to 2 previous errors
 

bevy_lint/tests/ui/borrowed_reborrowable/deferred.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut Deferred` instead of a re-borrowed `Deferred`
   --> tests/ui/borrowed_reborrowable/deferred.rs:17:22
    |
 17 | fn mutable_reference(_param: &mut Deferred<CommandQueue>) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `Deferred` instead: `mut _param: bevy::prelude::Deferred<'_, bevy::bevy_ecs::world::CommandQueue>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `Deferred` instead: `mut _param: Deferred<CommandQueue>`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/deferred.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut Deferred` instead of a re-borrowed `Deferred`
   --> tests/ui/borrowed_reborrowable/deferred.rs:23:33
    |
 23 | fn mutable_reference_return<'a>(_param: &'a mut Deferred<CommandQueue>) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `Deferred` instead: `mut _param: bevy::prelude::Deferred<'_, bevy::bevy_ecs::world::CommandQueue>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `Deferred` instead: `mut _param: Deferred<CommandQueue>`
 
 error: aborting due to 2 previous errors
 

bevy_lint/tests/ui/borrowed_reborrowable/deferred_world.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut DeferredWorld` instead of a re-borrowed `DeferredWo
   --> tests/ui/borrowed_reborrowable/deferred_world.rs:17:22
    |
 17 | fn mutable_reference(_param: &mut DeferredWorld) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `DeferredWorld` instead: `mut _param: bevy::bevy_ecs::world::DeferredWorld<'_>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `DeferredWorld` instead: `mut _param: DeferredWorld`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/deferred_world.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut DeferredWorld` instead of a re-borrowed `DeferredWo
   --> tests/ui/borrowed_reborrowable/deferred_world.rs:23:33
    |
 23 | fn mutable_reference_return<'a>(_param: &'a mut DeferredWorld) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `DeferredWorld` instead: `mut _param: bevy::bevy_ecs::world::DeferredWorld<'_>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `DeferredWorld` instead: `mut _param: DeferredWorld`
 
 error: aborting due to 2 previous errors
 

bevy_lint/tests/ui/borrowed_reborrowable/entity_commands.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut EntityCommands` instead of a re-borrowed `EntityCom
   --> tests/ui/borrowed_reborrowable/entity_commands.rs:17:22
    |
 17 | fn mutable_reference(_param: &mut EntityCommands) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `EntityCommands` instead: `mut _param: bevy::prelude::EntityCommands<'_>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `EntityCommands` instead: `mut _param: EntityCommands`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/entity_commands.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut EntityCommands` instead of a re-borrowed `EntityCom
   --> tests/ui/borrowed_reborrowable/entity_commands.rs:23:33
    |
 23 | fn mutable_reference_return<'a>(_param: &'a mut EntityCommands) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `EntityCommands` instead: `mut _param: bevy::prelude::EntityCommands<'_>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `EntityCommands` instead: `mut _param: EntityCommands`
 
 error: aborting due to 2 previous errors
 

bevy_lint/tests/ui/borrowed_reborrowable/entity_mut.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut EntityMut` instead of a re-borrowed `EntityMut`
   --> tests/ui/borrowed_reborrowable/entity_mut.rs:17:22
    |
 17 | fn mutable_reference(_param: &mut EntityMut) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^ help: use `EntityMut` instead: `mut _param: bevy::prelude::EntityMut<'_>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^ help: use `EntityMut` instead: `mut _param: EntityMut`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/entity_mut.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut EntityMut` instead of a re-borrowed `EntityMut`
   --> tests/ui/borrowed_reborrowable/entity_mut.rs:23:33
    |
 23 | fn mutable_reference_return<'a>(_param: &'a mut EntityMut) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `EntityMut` instead: `mut _param: bevy::prelude::EntityMut<'_>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `EntityMut` instead: `mut _param: EntityMut`
 
 error: aborting due to 2 previous errors
 

bevy_lint/tests/ui/borrowed_reborrowable/filtered_entity_mut.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut FilteredEntityMut` instead of a re-borrowed `Filter
   --> tests/ui/borrowed_reborrowable/filtered_entity_mut.rs:17:22
    |
 17 | fn mutable_reference(_param: &mut FilteredEntityMut) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `FilteredEntityMut` instead: `mut _param: bevy::bevy_ecs::world::FilteredEntityMut<'_>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `FilteredEntityMut` instead: `mut _param: FilteredEntityMut`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/filtered_entity_mut.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut FilteredEntityMut` instead of a re-borrowed `Filter
   --> tests/ui/borrowed_reborrowable/filtered_entity_mut.rs:23:33
    |
 23 | fn mutable_reference_return<'a>(_param: &'a mut FilteredEntityMut) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `FilteredEntityMut` instead: `mut _param: bevy::bevy_ecs::world::FilteredEntityMut<'_>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `FilteredEntityMut` instead: `mut _param: FilteredEntityMut`
 
 error: aborting due to 2 previous errors
 

bevy_lint/tests/ui/borrowed_reborrowable/mut_typed.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut Mut` instead of a re-borrowed `Mut`
   --> tests/ui/borrowed_reborrowable/mut_typed.rs:17:22
    |
 17 | fn mutable_reference(_param: &mut Mut<Name>) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^ help: use `Mut` instead: `mut _param: bevy::prelude::Mut<'_, bevy::prelude::Name>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^ help: use `Mut` instead: `mut _param: Mut<Name>`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/mut_typed.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut Mut` instead of a re-borrowed `Mut`
   --> tests/ui/borrowed_reborrowable/mut_typed.rs:23:33
    |
 23 | fn mutable_reference_return<'a>(_param: &'a mut Mut<Name>) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `Mut` instead: `mut _param: bevy::prelude::Mut<'_, bevy::prelude::Name>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `Mut` instead: `mut _param: Mut<Name>`
 
 error: aborting due to 2 previous errors
 

bevy_lint/tests/ui/borrowed_reborrowable/mut_untyped.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut MutUntyped` instead of a re-borrowed `MutUntyped`
   --> tests/ui/borrowed_reborrowable/mut_untyped.rs:18:22
    |
 18 | fn mutable_reference(_param: &mut MutUntyped) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^ help: use `MutUntyped` instead: `mut _param: bevy::bevy_ecs::change_detection::MutUntyped<'_>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^ help: use `MutUntyped` instead: `mut _param: MutUntyped`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/mut_untyped.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut MutUntyped` instead of a re-borrowed `MutUntyped`
   --> tests/ui/borrowed_reborrowable/mut_untyped.rs:24:33
    |
 24 | fn mutable_reference_return<'a>(_param: &'a mut MutUntyped) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `MutUntyped` instead: `mut _param: bevy::bevy_ecs::change_detection::MutUntyped<'_>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `MutUntyped` instead: `mut _param: MutUntyped`
 
 error: aborting due to 2 previous errors
 

bevy_lint/tests/ui/borrowed_reborrowable/non_send_mut.stderr

@@ -2,7 +2,7 @@ error: parameter takes `&mut NonSendMut` instead of a re-borrowed `NonSendMut`
   --> tests/ui/borrowed_reborrowable/non_send_mut.rs:19:22
    |
 19 | fn mutable_reference(_param: &mut NonSendMut<MyResource>) {
-   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `NonSendMut` instead: `mut _param: bevy::prelude::NonSendMut<'_, MyResource>`
+   |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `NonSendMut` instead: `mut _param: NonSendMut<MyResource>`
    |
 note: the lint level is defined here
   --> tests/ui/borrowed_reborrowable/non_send_mut.rs:5:9
@@ -14,7 +14,7 @@ error: parameter takes `&mut NonSendMut` instead of a re-borrowed `NonSendMut`
   --> tests/ui/borrowed_reborrowable/non_send_mut.rs:25:33
    |
 25 | fn mutable_reference_return<'a>(_param: &'a mut NonSendMut<MyResource>) -> usize {
-   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `NonSendMut` instead: `mut _param: bevy::prelude::NonSendMut<'_, MyResource>`
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `NonSendMut` instead: `mut _param: NonSendMut<MyResource>`
 
 error: aborting due to 2 previous errors