[beta] Clippy beta backport

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
 

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

@@ -1,6 +1,7 @@
 //@run-rustfix
 // rustfix-only-machine-applicable
 #![feature(lint_reasons)]
+#![warn(clippy::redundant_clone)]
 #![allow(clippy::drop_non_drop, clippy::implicit_clone, clippy::uninlined_format_args)]
 
 use std::ffi::OsString;

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

@@ -1,6 +1,7 @@
 //@run-rustfix
 // rustfix-only-machine-applicable
 #![feature(lint_reasons)]
+#![warn(clippy::redundant_clone)]
 #![allow(clippy::drop_non_drop, clippy::implicit_clone, clippy::uninlined_format_args)]
 
 use std::ffi::OsString;