submodules: update clippy from 326b220 to 7907abe

Changes:
````
Rustup to rust-lang/rust#70634
Update clippy_lints/src/types.rs
Update types.rs
Update types.rs
Improve docs for option_option
useless Rc<Rc<T>>, Rc<Box<T>>, Rc<&T>, Box<&T>
Allow let_underscore
Update option_option ui test
Test for ignoring let_underscore_must_use
Downgrade option_option to pedantic
````

Fixes #70709

CHANGELOG.md

@@ -1433,6 +1433,7 @@ Released 2018-09-13
 [`range_plus_one`]: https://rust-lang.github.io/rust-clippy/master/index.html#range_plus_one
 [`range_step_by_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#range_step_by_zero
 [`range_zip_with_len`]: https://rust-lang.github.io/rust-clippy/master/index.html#range_zip_with_len
+[`redundant_allocation`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_allocation
 [`redundant_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_clone
 [`redundant_closure`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure
 [`redundant_closure_call`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure_call

clippy_lints/src/escape.rs

@@ -2,10 +2,10 @@ use rustc_hir::intravisit;
 use rustc_hir::{self, Body, FnDecl, HirId, HirIdSet, ItemKind, Node};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
+use rustc_target::abi::LayoutOf;
 use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, Place, PlaceBase};
 
 use crate::utils::span_lint;

clippy_lints/src/large_enum_variant.rs

@@ -4,8 +4,8 @@ use crate::utils::{snippet_opt, span_lint_and_then};
 use rustc_errors::Applicability;
 use rustc_hir::{Item, ItemKind, VariantData};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::layout::LayoutOf;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_target::abi::LayoutOf;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for large size differences between variants on

clippy_lints/src/let_underscore.rs

@@ -1,5 +1,5 @@
 use if_chain::if_chain;
-use rustc_hir::{PatKind, Stmt, StmtKind};
+use rustc_hir::{Local, PatKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -66,13 +66,12 @@ const SYNC_GUARD_PATHS: [&[&str]; 3] = [
 ];
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LetUnderscore {
-    fn check_stmt(&mut self, cx: &LateContext<'_, '_>, stmt: &Stmt<'_>) {
-        if in_external_macro(cx.tcx.sess, stmt.span) {
+    fn check_local(&mut self, cx: &LateContext<'_, '_>, local: &Local<'_>) {
+        if in_external_macro(cx.tcx.sess, local.span) {
             return;
         }
 
         if_chain! {
-            if let StmtKind::Local(ref local) = stmt.kind;
             if let PatKind::Wild = local.pat.kind;
             if let Some(ref init) = local.init;
             then {
@@ -81,7 +80,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LetUnderscore {
                     span_lint_and_help(
                         cx,
                         LET_UNDERSCORE_LOCK,
-                        stmt.span,
+                        local.span,
                         "non-binding let on a synchronization lock",
                         "consider using an underscore-prefixed named \
                             binding or dropping explicitly with `std::mem::drop`"
@@ -90,15 +89,15 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LetUnderscore {
                     span_lint_and_help(
                         cx,
                         LET_UNDERSCORE_MUST_USE,
-                        stmt.span,
+                        local.span,
                         "non-binding let on an expression with `#[must_use]` type",
                         "consider explicitly using expression value"
                     )
                 } else if is_must_use_func_call(cx, init) {
                     span_lint_and_help(
                         cx,
                         LET_UNDERSCORE_MUST_USE,
-                        stmt.span,
+                        local.span,
                         "non-binding let on a result of a `#[must_use]` function",
                         "consider explicitly using function result"
                     )

clippy_lints/src/lib.rs

@@ -811,6 +811,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         &types::LET_UNIT_VALUE,
         &types::LINKEDLIST,
         &types::OPTION_OPTION,
+        &types::REDUNDANT_ALLOCATION,
         &types::TYPE_COMPLEXITY,
         &types::UNIT_ARG,
         &types::UNIT_CMP,
@@ -1125,6 +1126,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&types::CAST_SIGN_LOSS),
         LintId::of(&types::INVALID_UPCAST_COMPARISONS),
         LintId::of(&types::LINKEDLIST),
+        LintId::of(&types::OPTION_OPTION),
         LintId::of(&unicode::NON_ASCII_LITERAL),
         LintId::of(&unicode::UNICODE_NOT_NFC),
         LintId::of(&unused_self::UNUSED_SELF),
@@ -1375,7 +1377,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&types::FN_TO_NUMERIC_CAST_WITH_TRUNCATION),
         LintId::of(&types::IMPLICIT_HASHER),
         LintId::of(&types::LET_UNIT_VALUE),
-        LintId::of(&types::OPTION_OPTION),
+        LintId::of(&types::REDUNDANT_ALLOCATION),
         LintId::of(&types::TYPE_COMPLEXITY),
         LintId::of(&types::UNIT_ARG),
         LintId::of(&types::UNIT_CMP),
@@ -1565,7 +1567,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&transmute::TRANSMUTE_PTR_TO_REF),
         LintId::of(&types::BORROWED_BOX),
         LintId::of(&types::CHAR_LIT_AS_U8),
-        LintId::of(&types::OPTION_OPTION),
         LintId::of(&types::TYPE_COMPLEXITY),
         LintId::of(&types::UNIT_ARG),
         LintId::of(&types::UNNECESSARY_CAST),
@@ -1661,6 +1662,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
         LintId::of(&slow_vector_initialization::SLOW_VECTOR_INITIALIZATION),
         LintId::of(&trivially_copy_pass_by_ref::TRIVIALLY_COPY_PASS_BY_REF),
         LintId::of(&types::BOX_VEC),
+        LintId::of(&types::REDUNDANT_ALLOCATION),
         LintId::of(&vec::USELESS_VEC),
     ]);
 

clippy_lints/src/types.rs

@@ -17,12 +17,12 @@ use rustc_hir::{
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::hir::map::Map;
 use rustc_middle::lint::in_external_macro;
-use rustc_middle::ty::layout::LayoutOf;
 use rustc_middle::ty::{self, InferTy, Ty, TyCtxt, TypeckTables};
 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use rustc_span::source_map::Span;
 use rustc_span::symbol::{sym, Symbol};
+use rustc_target::abi::LayoutOf;
 use rustc_target::spec::abi::Abi;
 use rustc_typeck::hir_ty_to_ty;
 
@@ -99,16 +99,33 @@ declare_clippy_lint! {
     /// represents an optional optional value which is logically the same thing as an optional
     /// value but has an unneeded extra level of wrapping.
     ///
+    /// If you have a case where `Some(Some(_))`, `Some(None)` and `None` are distinct cases,
+    /// consider a custom `enum` instead, with clear names for each case.
+    ///
     /// **Known problems:** None.
     ///
     /// **Example**
     /// ```rust
-    /// fn x() -> Option<Option<u32>> {
+    /// fn get_data() -> Option<Option<u32>> {
     ///     None
     /// }
     /// ```
+    ///
+    /// Better:
+    ///
+    /// ```rust
+    /// pub enum Contents {
+    ///     Data(Vec<u8>), // Was Some(Some(Vec<u8>))
+    ///     NotYetFetched, // Was Some(None)
+    ///     None,          // Was None
+    /// }
+    ///
+    /// fn get_data() -> Contents {
+    ///     Contents::None
+    /// }
+    /// ```
     pub OPTION_OPTION,
-    complexity,
+    pedantic,
     "usage of `Option<Option<T>>`"
 }
 
@@ -171,11 +188,35 @@ declare_clippy_lint! {
     "a borrow of a boxed type"
 }
 
+declare_clippy_lint! {
+    /// **What it does:** Checks for use of redundant allocations anywhere in the code.
+    ///
+    /// **Why is this bad?** Expressions such as `Rc<&T>`, `Rc<Rc<T>>`, `Rc<Box<T>>`, `Box<&T>`
+    /// add an unnecessary level of indirection.
+    ///
+    /// **Known problems:** None.
+    ///
+    /// **Example:**
+    /// ```rust
+    /// # use std::rc::Rc;
+    /// fn foo(bar: Rc<&usize>) {}
+    /// ```
+    ///
+    /// Better:
+    ///
+    /// ```rust
+    /// fn foo(bar: &usize) {}
+    /// ```
+    pub REDUNDANT_ALLOCATION,
+    perf,
+    "redundant allocation"
+}
+
 pub struct Types {
     vec_box_size_threshold: u64,
 }
 
-impl_lint_pass!(Types => [BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX]);
+impl_lint_pass!(Types => [BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX, REDUNDANT_ALLOCATION]);
 
 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Types {
     fn check_fn(
@@ -217,7 +258,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Types {
 }
 
 /// Checks if `qpath` has last segment with type parameter matching `path`
-fn match_type_parameter(cx: &LateContext<'_, '_>, qpath: &QPath<'_>, path: &[&str]) -> bool {
+fn match_type_parameter(cx: &LateContext<'_, '_>, qpath: &QPath<'_>, path: &[&str]) -> Option<Span> {
     let last = last_path_segment(qpath);
     if_chain! {
         if let Some(ref params) = last.args;
@@ -230,10 +271,27 @@ fn match_type_parameter(cx: &LateContext<'_, '_>, qpath: &QPath<'_>, path: &[&st
         if let Some(did) = qpath_res(cx, qpath, ty.hir_id).opt_def_id();
         if match_def_path(cx, did, path);
         then {
-            return true;
+            return Some(ty.span);
         }
     }
-    false
+    None
+}
+
+fn match_borrows_parameter(_cx: &LateContext<'_, '_>, qpath: &QPath<'_>) -> Option<Span> {
+    let last = last_path_segment(qpath);
+    if_chain! {
+        if let Some(ref params) = last.args;
+        if !params.parenthesized;
+        if let Some(ty) = params.args.iter().find_map(|arg| match arg {
+            GenericArg::Type(ty) => Some(ty),
+            _ => None,
+        });
+        if let TyKind::Rptr(..) = ty.kind;
+        then {
+            return Some(ty.span);
+        }
+    }
+    None
 }
 
 impl Types {
@@ -257,6 +315,7 @@ impl Types {
     /// The parameter `is_local` distinguishes the context of the type; types from
     /// local bindings should only be checked for the `BORROWED_BOX` lint.
     #[allow(clippy::too_many_lines)]
+    #[allow(clippy::cognitive_complexity)]
     fn check_ty(&mut self, cx: &LateContext<'_, '_>, hir_ty: &hir::Ty<'_>, is_local: bool) {
         if hir_ty.span.from_expansion() {
             return;
@@ -267,7 +326,19 @@ impl Types {
                 let res = qpath_res(cx, qpath, hir_id);
                 if let Some(def_id) = res.opt_def_id() {
                     if Some(def_id) == cx.tcx.lang_items().owned_box() {
-                        if match_type_parameter(cx, qpath, &paths::VEC) {
+                        if let Some(span) = match_borrows_parameter(cx, qpath) {
+                            span_lint_and_sugg(
+                                cx,
+                                REDUNDANT_ALLOCATION,
+                                hir_ty.span,
+                                "usage of `Box<&T>`",
+                                "try",
+                                snippet(cx, span, "..").to_string(),
+                                Applicability::MachineApplicable,
+                            );
+                            return; // don't recurse into the type
+                        }
+                        if match_type_parameter(cx, qpath, &paths::VEC).is_some() {
                             span_lint_and_help(
                                 cx,
                                 BOX_VEC,
@@ -277,6 +348,43 @@ impl Types {
                             );
                             return; // don't recurse into the type
                         }
+                    } else if Some(def_id) == cx.tcx.lang_items().rc() {
+                        if let Some(span) = match_type_parameter(cx, qpath, &paths::RC) {
+                            span_lint_and_sugg(
+                                cx,
+                                REDUNDANT_ALLOCATION,
+                                hir_ty.span,
+                                "usage of `Rc<Rc<T>>`",
+                                "try",
+                                snippet(cx, span, "..").to_string(),
+                                Applicability::MachineApplicable,
+                            );
+                            return; // don't recurse into the type
+                        }
+                        if let Some(span) = match_type_parameter(cx, qpath, &paths::BOX) {
+                            span_lint_and_sugg(
+                                cx,
+                                REDUNDANT_ALLOCATION,
+                                hir_ty.span,
+                                "usage of `Rc<Box<T>>`",
+                                "try",
+                                snippet(cx, span, "..").to_string(),
+                                Applicability::MachineApplicable,
+                            );
+                            return; // don't recurse into the type
+                        }
+                        if let Some(span) = match_borrows_parameter(cx, qpath) {
+                            span_lint_and_sugg(
+                                cx,
+                                REDUNDANT_ALLOCATION,
+                                hir_ty.span,
+                                "usage of `Rc<&T>`",
+                                "try",
+                                snippet(cx, span, "..").to_string(),
+                                Applicability::MachineApplicable,
+                            );
+                            return; // don't recurse into the type
+                        }
                     } else if cx.tcx.is_diagnostic_item(Symbol::intern("vec_type"), def_id) {
                         if_chain! {
                             // Get the _ part of Vec<_>
@@ -314,7 +422,7 @@ impl Types {
                             }
                         }
                     } else if match_def_path(cx, def_id, &paths::OPTION) {
-                        if match_type_parameter(cx, qpath, &paths::OPTION) {
+                        if match_type_parameter(cx, qpath, &paths::OPTION).is_some() {
                             span_lint(
                                 cx,
                                 OPTION_OPTION,

clippy_lints/src/utils/mod.rs

@@ -41,16 +41,12 @@ use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, Level, Lint, LintContext};
 use rustc_middle::hir::map::Map;
 use rustc_middle::traits;
-use rustc_middle::ty::{
-    self,
-    layout::{self, IntegerExt},
-    subst::GenericArg,
-    Binder, Ty, TyCtxt, TypeFoldable,
-};
+use rustc_middle::ty::{self, layout::IntegerExt, subst::GenericArg, Binder, Ty, TyCtxt, TypeFoldable};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use rustc_span::source_map::original_sp;
 use rustc_span::symbol::{self, kw, Symbol};
 use rustc_span::{BytePos, Pos, Span, DUMMY_SP};
+use rustc_target::abi::Integer;
 use rustc_trait_selection::traits::predicate_for_trait_def;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::query::normalize::AtExt;
@@ -1080,9 +1076,7 @@ pub fn get_arg_name(pat: &Pat<'_>) -> Option<ast::Name> {
 }
 
 pub fn int_bits(tcx: TyCtxt<'_>, ity: ast::IntTy) -> u64 {
-    layout::Integer::from_attr(&tcx, attr::IntType::SignedInt(ity))
-        .size()
-        .bits()
+    Integer::from_attr(&tcx, attr::IntType::SignedInt(ity)).size().bits()
 }
 
 #[allow(clippy::cast_possible_wrap)]
@@ -1101,9 +1095,7 @@ pub fn unsext(tcx: TyCtxt<'_>, u: i128, ity: ast::IntTy) -> u128 {
 
 /// clip unused bytes
 pub fn clip(tcx: TyCtxt<'_>, u: u128, ity: ast::UintTy) -> u128 {
-    let bits = layout::Integer::from_attr(&tcx, attr::IntType::UnsignedInt(ity))
-        .size()
-        .bits();
+    let bits = Integer::from_attr(&tcx, attr::IntType::UnsignedInt(ity)).size().bits();
     let amt = 128 - bits;
     (u << amt) >> amt
 }

clippy_lints/src/utils/paths.rs

@@ -10,6 +10,7 @@ pub const BEGIN_PANIC: [&str; 3] = ["std", "panicking", "begin_panic"];
 pub const BEGIN_PANIC_FMT: [&str; 3] = ["std", "panicking", "begin_panic_fmt"];
 pub const BINARY_HEAP: [&str; 4] = ["alloc", "collections", "binary_heap", "BinaryHeap"];
 pub const BORROW_TRAIT: [&str; 3] = ["core", "borrow", "Borrow"];
+pub const BOX: [&str; 3] = ["alloc", "boxed", "Box"];
 pub const BTREEMAP: [&str; 5] = ["alloc", "collections", "btree", "map", "BTreeMap"];
 pub const BTREEMAP_ENTRY: [&str; 5] = ["alloc", "collections", "btree", "map", "Entry"];
 pub const BTREESET: [&str; 5] = ["alloc", "collections", "btree", "set", "BTreeSet"];