Auto merge of #113417 - flip1995:clippy_beta_backport, r=Manishearth

[beta] Clippy beta backport

Backported PRs:

- rust-lang/rust-clippy#10813
- rust-lang/rust-clippy#10865
- rust-lang/rust-clippy#10873
- rust-lang/rust-clippy#10992

Those address bugs, that were either introduced with 1.71 and that we would like to address before they get into stable or bugs that were introduced in 1.70 and that we would like to be fixed in 1.71 already.

Detailed arguments for the backports of those PRs are in the PRs (mostly).

r? `@Mark-Simulacrum`

Author: bors

src/tools/clippy/clippy_lints/src/default_constructed_unit_structs.rs

@@ -1,4 +1,4 @@
-use clippy_utils::{diagnostics::span_lint_and_sugg, match_def_path, paths};
+use clippy_utils::{diagnostics::span_lint_and_sugg, is_ty_alias, match_def_path, paths};
 use hir::{def::Res, ExprKind};
 use rustc_errors::Applicability;
 use rustc_hir as hir;
@@ -43,12 +43,23 @@ declare_clippy_lint! {
 }
 declare_lint_pass!(DefaultConstructedUnitStructs => [DEFAULT_CONSTRUCTED_UNIT_STRUCTS]);
 
+fn is_alias(ty: hir::Ty<'_>) -> bool {
+    if let hir::TyKind::Path(ref qpath) = ty.kind {
+        is_ty_alias(qpath)
+    } else {
+        false
+    }
+}
+
 impl LateLintPass<'_> for DefaultConstructedUnitStructs {
     fn check_expr<'tcx>(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
         if_chain!(
             // make sure we have a call to `Default::default`
             if let hir::ExprKind::Call(fn_expr, &[]) = expr.kind;
-            if let ExprKind::Path(ref qpath@ hir::QPath::TypeRelative(_,_)) = fn_expr.kind;
+            if let ExprKind::Path(ref qpath @ hir::QPath::TypeRelative(base, _)) = fn_expr.kind;
+            // make sure this isn't a type alias:
+            // `<Foo as Bar>::Assoc` cannot be used as a constructor
+            if !is_alias(*base);
             if let Res::Def(_, def_id) = cx.qpath_res(qpath, fn_expr.hir_id);
             if match_def_path(cx, def_id, &paths::DEFAULT_TRAIT_METHOD);
             // make sure we have a struct with no fields (unit struct)

src/tools/clippy/clippy_lints/src/items_after_test_module.rs

@@ -1,4 +1,4 @@
-use clippy_utils::{diagnostics::span_lint_and_help, is_in_cfg_test};
+use clippy_utils::{diagnostics::span_lint_and_help, is_from_proc_macro, is_in_cfg_test};
 use rustc_hir::{HirId, ItemId, ItemKind, Mod};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
@@ -59,6 +59,7 @@ impl LateLintPass<'_> for ItemsAfterTestModule {
             if !matches!(item.kind, ItemKind::Mod(_));
             if !is_in_cfg_test(cx.tcx, itid.hir_id()); // The item isn't in the testing module itself
             if !in_external_macro(cx.sess(), item.span);
+            if !is_from_proc_macro(cx, item);
 
             then {
                 span_lint_and_help(cx, ITEMS_AFTER_TEST_MODULE, test_mod_span.unwrap().with_hi(item.span.hi()), "items were found after the testing module", None, "move the items to before the testing module was defined");

src/tools/clippy/clippy_lints/src/let_with_type_underscore.rs

@@ -1,4 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::source::snippet;
 use rustc_hir::{Local, TyKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::lint::in_external_macro;
@@ -25,14 +26,21 @@ declare_clippy_lint! {
 declare_lint_pass!(UnderscoreTyped => [LET_WITH_TYPE_UNDERSCORE]);
 
 impl LateLintPass<'_> for UnderscoreTyped {
-    fn check_local<'tcx>(&mut self, cx: &LateContext<'tcx>, local: &'tcx Local<'tcx>) {
+    fn check_local(&mut self, cx: &LateContext<'_>, local: &Local<'_>) {
         if_chain! {
             if !in_external_macro(cx.tcx.sess, local.span);
             if let Some(ty) = local.ty; // Ensure that it has a type defined
             if let TyKind::Infer = &ty.kind; // that type is '_'
             if local.span.ctxt() == ty.span.ctxt();
             then {
-                span_lint_and_help(cx,
+                // NOTE: Using `is_from_proc_macro` on `init` will require that it's initialized,
+                // this doesn't. Alternatively, `WithSearchPat` can be implemented for `Ty`
+                if snippet(cx, ty.span, "_").trim() != "_" {
+                    return;
+                }
+
+                span_lint_and_help(
+                    cx,
                     LET_WITH_TYPE_UNDERSCORE,
                     local.span,
                     "variable declared with type underscore",

src/tools/clippy/clippy_lints/src/redundant_clone.rs

@@ -57,7 +57,7 @@ declare_clippy_lint! {
     /// ```
     #[clippy::version = "1.32.0"]
     pub REDUNDANT_CLONE,
-    perf,
+    nursery,
     "`clone()` of an owned value that is going to be dropped immediately"
 }
 

src/tools/clippy/clippy_utils/src/lib.rs

@@ -287,7 +287,7 @@ pub fn is_wild(pat: &Pat<'_>) -> bool {
 /// Checks if the given `QPath` belongs to a type alias.
 pub fn is_ty_alias(qpath: &QPath<'_>) -> bool {
     match *qpath {
-        QPath::Resolved(_, path) => matches!(path.res, Res::Def(DefKind::TyAlias, ..)),
+        QPath::Resolved(_, path) => matches!(path.res, Res::Def(DefKind::TyAlias | DefKind::AssocTy, ..)),
         QPath::TypeRelative(ty, _) if let TyKind::Path(qpath) = ty.kind => { is_ty_alias(&qpath) },
         _ => false,
     }

src/tools/clippy/tests/ui/default_constructed_unit_structs.fixed

@@ -101,6 +101,28 @@ struct EmptyStruct {}
 #[non_exhaustive]
 struct NonExhaustiveStruct;
 
+mod issue_10755 {
+    struct Sqlite {}
+
+    trait HasArguments<'q> {
+        type Arguments;
+    }
+
+    impl<'q> HasArguments<'q> for Sqlite {
+        type Arguments = std::marker::PhantomData<&'q ()>;
+    }
+
+    type SqliteArguments<'q> = <Sqlite as HasArguments<'q>>::Arguments;
+
+    fn foo() {
+        // should not lint
+        // type alias cannot be used as a constructor
+        let _ = <Sqlite as HasArguments>::Arguments::default();
+
+        let _ = SqliteArguments::default();
+    }
+}
+
 fn main() {
     // should lint
     let _ = PhantomData::<usize>;

src/tools/clippy/tests/ui/default_constructed_unit_structs.rs

@@ -101,6 +101,28 @@ struct EmptyStruct {}
 #[non_exhaustive]
 struct NonExhaustiveStruct;
 
+mod issue_10755 {
+    struct Sqlite {}
+
+    trait HasArguments<'q> {
+        type Arguments;
+    }
+
+    impl<'q> HasArguments<'q> for Sqlite {
+        type Arguments = std::marker::PhantomData<&'q ()>;
+    }
+
+    type SqliteArguments<'q> = <Sqlite as HasArguments<'q>>::Arguments;
+
+    fn foo() {
+        // should not lint
+        // type alias cannot be used as a constructor
+        let _ = <Sqlite as HasArguments>::Arguments::default();
+
+        let _ = SqliteArguments::default();
+    }
+}
+
 fn main() {
     // should lint
     let _ = PhantomData::<usize>::default();

src/tools/clippy/tests/ui/default_constructed_unit_structs.stderr

@@ -13,25 +13,25 @@ LL |             inner: PhantomData::default(),
    |                               ^^^^^^^^^^^ help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:106:33
+  --> $DIR/default_constructed_unit_structs.rs:128:33
    |
 LL |     let _ = PhantomData::<usize>::default();
    |                                 ^^^^^^^^^^^ help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:107:42
+  --> $DIR/default_constructed_unit_structs.rs:129:42
    |
 LL |     let _: PhantomData<i32> = PhantomData::default();
    |                                          ^^^^^^^^^^^ help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:108:55
+  --> $DIR/default_constructed_unit_structs.rs:130:55
    |
 LL |     let _: PhantomData<i32> = std::marker::PhantomData::default();
    |                                                       ^^^^^^^^^^^ help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> $DIR/default_constructed_unit_structs.rs:109:23
+  --> $DIR/default_constructed_unit_structs.rs:131:23
    |
 LL |     let _ = UnitStruct::default();
    |                       ^^^^^^^^^^^ help: remove this call to `default`

src/tools/clippy/tests/ui/let_with_type_underscore.rs

@@ -1,19 +1,42 @@
+//@aux-build: proc_macros.rs
 #![allow(unused)]
 #![warn(clippy::let_with_type_underscore)]
-#![allow(clippy::let_unit_value)]
+#![allow(clippy::let_unit_value, clippy::needless_late_init)]
+
+extern crate proc_macros;
 
 fn func() -> &'static str {
     ""
 }
 
+#[rustfmt::skip]
 fn main() {
     // Will lint
     let x: _ = 1;
     let _: _ = 2;
     let x: _ = func();
+    let x: _;
+    x = ();
 
     let x = 1; // Will not lint, Rust infers this to an integer before Clippy
     let x = func();
     let x: Vec<_> = Vec::<u32>::new();
     let x: [_; 1] = [1];
+    let x : _ = 1;
+
+    // Do not lint from procedural macros
+    proc_macros::with_span! {
+        span
+        let x: _ = ();
+        // Late initialization
+        let x: _;
+        x = ();
+        // Ensure weird formatting will not break it (hopefully)
+        let x : _ = 1;
+        let x
+: _ = 1;
+        let                   x :              
+        _;
+        x = ();
+    };
 }

src/tools/clippy/tests/ui/let_with_type_underscore.stderr

@@ -1,39 +1,63 @@
 error: variable declared with type underscore
-  --> $DIR/let_with_type_underscore.rs:11:5
+  --> $DIR/let_with_type_underscore.rs:15:5
    |
 LL |     let x: _ = 1;
    |     ^^^^^^^^^^^^^
    |
 help: remove the explicit type `_` declaration
-  --> $DIR/let_with_type_underscore.rs:11:10
+  --> $DIR/let_with_type_underscore.rs:15:10
    |
 LL |     let x: _ = 1;
    |          ^^^
    = note: `-D clippy::let-with-type-underscore` implied by `-D warnings`
 
 error: variable declared with type underscore
-  --> $DIR/let_with_type_underscore.rs:12:5
+  --> $DIR/let_with_type_underscore.rs:16:5
    |
 LL |     let _: _ = 2;
    |     ^^^^^^^^^^^^^
    |
 help: remove the explicit type `_` declaration
-  --> $DIR/let_with_type_underscore.rs:12:10
+  --> $DIR/let_with_type_underscore.rs:16:10
    |
 LL |     let _: _ = 2;
    |          ^^^
 
 error: variable declared with type underscore
-  --> $DIR/let_with_type_underscore.rs:13:5
+  --> $DIR/let_with_type_underscore.rs:17:5
    |
 LL |     let x: _ = func();
    |     ^^^^^^^^^^^^^^^^^^
    |
 help: remove the explicit type `_` declaration
-  --> $DIR/let_with_type_underscore.rs:13:10
+  --> $DIR/let_with_type_underscore.rs:17:10
    |
 LL |     let x: _ = func();
    |          ^^^
 
-error: aborting due to 3 previous errors
+error: variable declared with type underscore
+  --> $DIR/let_with_type_underscore.rs:18:5
+   |
+LL |     let x: _;
+   |     ^^^^^^^^^
+   |
+help: remove the explicit type `_` declaration
+  --> $DIR/let_with_type_underscore.rs:18:10
+   |
+LL |     let x: _;
+   |          ^^^
+
+error: variable declared with type underscore
+  --> $DIR/let_with_type_underscore.rs:25:5
+   |
+LL |     let x : _ = 1;
+   |     ^^^^^^^^^^^^^^
+   |
+help: remove the explicit type `_` declaration
+  --> $DIR/let_with_type_underscore.rs:25:10
+   |
+LL |     let x : _ = 1;
+   |          ^^^^
+
+error: aborting due to 5 previous errors