Auto merge of rust-lang#78774 - flip1995:clippyup, r=Manishearth

Update Clippy

Biweekly Clippy update

r? `@Manishearth`

Author: bors

src/tools/clippy/.github/driver.sh

@@ -24,16 +24,16 @@ unset CARGO_MANIFEST_DIR
 # FIXME: How to match the clippy invocation in compile-test.rs?
 ./target/debug/clippy-driver -Dwarnings -Aunused -Zui-testing --emit metadata --crate-type bin tests/ui/double_neg.rs 2>double_neg.stderr && exit 1
 sed -e "s,tests/ui,\$DIR," -e "/= help/d" double_neg.stderr >normalized.stderr
-diff normalized.stderr tests/ui/double_neg.stderr
+diff -u normalized.stderr tests/ui/double_neg.stderr
 
 # make sure "clippy-driver --rustc --arg" and "rustc --arg" behave the same
 SYSROOT=$(rustc --print sysroot)
-diff <(LD_LIBRARY_PATH=${SYSROOT}/lib ./target/debug/clippy-driver --rustc --version --verbose) <(rustc --version --verbose)
+diff -u <(LD_LIBRARY_PATH=${SYSROOT}/lib ./target/debug/clippy-driver --rustc --version --verbose) <(rustc --version --verbose)
 
 echo "fn main() {}" >target/driver_test.rs
 # we can't run 2 rustcs on the same file at the same time
 CLIPPY=$(LD_LIBRARY_PATH=${SYSROOT}/lib ./target/debug/clippy-driver ./target/driver_test.rs --rustc)
 RUSTC=$(rustc ./target/driver_test.rs)
-diff <($CLIPPY) <($RUSTC)
+diff -u <($CLIPPY) <($RUSTC)
 
 # TODO: CLIPPY_CONF_DIR / CARGO_MANIFEST_DIR

src/tools/clippy/CHANGELOG.md

@@ -22,7 +22,7 @@ Current beta, release 2020-11-19
 * [`map_err_ignore`] [#5998](https://github.com/rust-lang/rust-clippy/pull/5998)
 * [`rc_buffer`] [#6044](https://github.com/rust-lang/rust-clippy/pull/6044)
 * [`to_string_in_display`] [#5831](https://github.com/rust-lang/rust-clippy/pull/5831)
-* [`single_char_push_str`] [#5881](https://github.com/rust-lang/rust-clippy/pull/5881)
+* `single_char_push_str` [#5881](https://github.com/rust-lang/rust-clippy/pull/5881)
 
 ### Moves and Deprecations
 
@@ -1665,6 +1665,7 @@ Released 2018-09-13
 [`cognitive_complexity`]: https://rust-lang.github.io/rust-clippy/master/index.html#cognitive_complexity
 [`collapsible_if`]: https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
 [`comparison_chain`]: https://rust-lang.github.io/rust-clippy/master/index.html#comparison_chain
+[`comparison_to_empty`]: https://rust-lang.github.io/rust-clippy/master/index.html#comparison_to_empty
 [`copy_iterator`]: https://rust-lang.github.io/rust-clippy/master/index.html#copy_iterator
 [`create_dir`]: https://rust-lang.github.io/rust-clippy/master/index.html#create_dir
 [`crosspointer_transmute`]: https://rust-lang.github.io/rust-clippy/master/index.html#crosspointer_transmute
@@ -1713,6 +1714,7 @@ Released 2018-09-13
 [`extend_from_slice`]: https://rust-lang.github.io/rust-clippy/master/index.html#extend_from_slice
 [`extra_unused_lifetimes`]: https://rust-lang.github.io/rust-clippy/master/index.html#extra_unused_lifetimes
 [`fallible_impl_from`]: https://rust-lang.github.io/rust-clippy/master/index.html#fallible_impl_from
+[`field_reassign_with_default`]: https://rust-lang.github.io/rust-clippy/master/index.html#field_reassign_with_default
 [`filetype_is_file`]: https://rust-lang.github.io/rust-clippy/master/index.html#filetype_is_file
 [`filter_map`]: https://rust-lang.github.io/rust-clippy/master/index.html#filter_map
 [`filter_map_next`]: https://rust-lang.github.io/rust-clippy/master/index.html#filter_map_next
@@ -1731,6 +1733,7 @@ Released 2018-09-13
 [`for_loops_over_fallibles`]: https://rust-lang.github.io/rust-clippy/master/index.html#for_loops_over_fallibles
 [`forget_copy`]: https://rust-lang.github.io/rust-clippy/master/index.html#forget_copy
 [`forget_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#forget_ref
+[`from_iter_instead_of_collect`]: https://rust-lang.github.io/rust-clippy/master/index.html#from_iter_instead_of_collect
 [`future_not_send`]: https://rust-lang.github.io/rust-clippy/master/index.html#future_not_send
 [`get_last_with_len`]: https://rust-lang.github.io/rust-clippy/master/index.html#get_last_with_len
 [`get_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
@@ -1795,13 +1798,15 @@ Released 2018-09-13
 [`manual_async_fn`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_async_fn
 [`manual_memcpy`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_memcpy
 [`manual_non_exhaustive`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_non_exhaustive
+[`manual_ok_or`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_ok_or
 [`manual_range_contains`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_range_contains
 [`manual_saturating_arithmetic`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_saturating_arithmetic
 [`manual_strip`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_strip
 [`manual_swap`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_swap
 [`manual_unwrap_or`]: https://rust-lang.github.io/rust-clippy/master/index.html#manual_unwrap_or
 [`many_single_char_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#many_single_char_names
 [`map_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_clone
+[`map_collect_result_unit`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_collect_result_unit
 [`map_entry`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_entry
 [`map_err_ignore`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_err_ignore
 [`map_flatten`]: https://rust-lang.github.io/rust-clippy/master/index.html#map_flatten
@@ -1917,6 +1922,7 @@ Released 2018-09-13
 [`redundant_pub_crate`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_pub_crate
 [`redundant_static_lifetimes`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes
 [`ref_in_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_in_deref
+[`ref_option_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_option_ref
 [`regex_macro`]: https://rust-lang.github.io/rust-clippy/master/index.html#regex_macro
 [`repeat_once`]: https://rust-lang.github.io/rust-clippy/master/index.html#repeat_once
 [`replace_consts`]: https://rust-lang.github.io/rust-clippy/master/index.html#replace_consts
@@ -1937,8 +1943,8 @@ Released 2018-09-13
 [`should_assert_eq`]: https://rust-lang.github.io/rust-clippy/master/index.html#should_assert_eq
 [`should_implement_trait`]: https://rust-lang.github.io/rust-clippy/master/index.html#should_implement_trait
 [`similar_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#similar_names
+[`single_char_add_str`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_char_add_str
 [`single_char_pattern`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_char_pattern
-[`single_char_push_str`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_char_push_str
 [`single_component_path_imports`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_component_path_imports
 [`single_element_loop`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_element_loop
 [`single_match`]: https://rust-lang.github.io/rust-clippy/master/index.html#single_match

src/tools/clippy/CONTRIBUTING.md

@@ -63,9 +63,10 @@ To figure out how this syntax structure is encoded in the AST, it is recommended
 Usually the lint will end up to be a nested series of matches and ifs, [like so][deep-nesting].
 But we can make it nest-less by using [if_chain] macro, [like this][nest-less].
 
-[`E-medium`] issues are generally pretty easy too, though it's recommended you work on an E-easy issue first.
-They are mostly classified as [`E-medium`], since they might be somewhat involved code wise,
-but not difficult per-se.
+[`E-medium`] issues are generally pretty easy too, though it's recommended you work on an [`good first issue`]
+first. Sometimes they are only somewhat involved code wise, but not difficult per-se.
+Note that [`E-medium`] issues may require some knowledge of Clippy internals or some 
+debugging to find the actual problem behind the issue. 
 
 [`T-middle`] issues can be more involved and require verifying types. The [`ty`] module contains a
 lot of methods that are useful, though one of the most useful would be `expr_ty` (gives the type of

src/tools/clippy/README.md

@@ -167,18 +167,21 @@ You can add options to your code to `allow`/`warn`/`deny` Clippy lints:
 
 *   `allow`/`warn`/`deny` can be limited to a single function or module using `#[allow(...)]`, etc.
 
-Note: `deny` produces errors instead of warnings.
+Note: `allow` means to suppress the lint for your code. With `warn` the lint
+will only emit a warning, while with `deny` the lint will emit an error, when
+triggering for your code. An error causes clippy to exit with an error code, so
+is useful in scripts like CI/CD.
 
-If you do not want to include your lint levels in your code, you can globally enable/disable lints
-by passing extra flags to Clippy during the run:
+If you do not want to include your lint levels in your code, you can globally
+enable/disable lints by passing extra flags to Clippy during the run:
 
-To disable `lint_name`, run
+To allow `lint_name`, run
 
 ```terminal
 cargo clippy -- -A clippy::lint_name
 ```
 
-And to enable `lint_name`, run
+And to warn on `lint_name`, run
 
 ```terminal
 cargo clippy -- -W clippy::lint_name
@@ -190,7 +193,7 @@ can run Clippy with warnings for all lints enabled:
 cargo clippy -- -W clippy::pedantic
 ```
 
-If you care only about a single lint, you can allow all others and then explicitly reenable
+If you care only about a single lint, you can allow all others and then explicitly warn on
 the lint(s) you are interested in:
 ```terminal
 cargo clippy -- -A clippy::all -W clippy::useless_format -W clippy::...

src/tools/clippy/clippy_dev/src/ra_setup.rs

@@ -11,7 +11,7 @@ use std::path::PathBuf;
 // code. See https://github.com/rust-analyzer/rust-analyzer/issues/3517 and https://github.com/rust-lang/rust-clippy/issues/5514 for details
 
 pub fn run(rustc_path: Option<&str>) {
-    // we can unwrap here because the arg is required here
+    // we can unwrap here because the arg is required by clap
     let rustc_path = PathBuf::from(rustc_path.unwrap());
     assert!(rustc_path.is_dir(), "path is not a directory");
     let rustc_source_basedir = rustc_path.join("compiler");
@@ -49,6 +49,15 @@ fn inject_deps_into_manifest(
     cargo_toml: &str,
     lib_rs: &str,
 ) -> std::io::Result<()> {
+    // do not inject deps if we have aleady done so
+    if cargo_toml.contains("[target.'cfg(NOT_A_PLATFORM)'.dependencies]") {
+        eprintln!(
+            "cargo dev ra-setup: warning: deps already found inside {}, doing nothing.",
+            manifest_path
+        );
+        return Ok(());
+    }
+
     let extern_crates = lib_rs
         .lines()
         // get the deps

src/tools/clippy/clippy_lints/src/arithmetic.rs

@@ -88,9 +88,28 @@ impl<'tcx> LateLintPass<'tcx> for Arithmetic {
 
                 let (l_ty, r_ty) = (cx.typeck_results().expr_ty(l), cx.typeck_results().expr_ty(r));
                 if l_ty.peel_refs().is_integral() && r_ty.peel_refs().is_integral() {
-                    span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
-                    self.expr_span = Some(expr.span);
-                } else if l_ty.peel_refs().is_floating_point() && r_ty.peel_refs().is_floating_point() {
+                    match op.node {
+                        hir::BinOpKind::Div | hir::BinOpKind::Rem => match &r.kind {
+                            hir::ExprKind::Lit(_lit) => (),
+                            hir::ExprKind::Unary(hir::UnOp::UnNeg, expr) => {
+                                if let hir::ExprKind::Lit(lit) = &expr.kind {
+                                    if let rustc_ast::ast::LitKind::Int(1, _) = lit.node {
+                                        span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
+                                        self.expr_span = Some(expr.span);
+                                    }
+                                }
+                            },
+                            _ => {
+                                span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
+                                self.expr_span = Some(expr.span);
+                            },
+                        },
+                        _ => {
+                            span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
+                            self.expr_span = Some(expr.span);
+                        },
+                    }
+                } else if r_ty.peel_refs().is_floating_point() && r_ty.peel_refs().is_floating_point() {
                     span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected");
                     self.expr_span = Some(expr.span);
                 }

src/tools/clippy/clippy_lints/src/attrs.rs

@@ -16,6 +16,7 @@ use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
+use rustc_span::sym;
 use rustc_span::symbol::{Symbol, SymbolStr};
 use semver::Version;
 
@@ -286,14 +287,14 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
                     },
                     _ => {},
                 }
-                if items.is_empty() || !attr.has_name(sym!(deprecated)) {
+                if items.is_empty() || !attr.has_name(sym::deprecated) {
                     return;
                 }
                 for item in items {
                     if_chain! {
                         if let NestedMetaItem::MetaItem(mi) = &item;
                         if let MetaItemKind::NameValue(lit) = &mi.kind;
-                        if mi.has_name(sym!(since));
+                        if mi.has_name(sym::since);
                         then {
                             check_semver(cx, item.span(), lit);
                         }
@@ -309,7 +310,7 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
         }
         match item.kind {
             ItemKind::ExternCrate(..) | ItemKind::Use(..) => {
-                let skip_unused_imports = item.attrs.iter().any(|attr| attr.has_name(sym!(macro_use)));
+                let skip_unused_imports = item.attrs.iter().any(|attr| attr.has_name(sym::macro_use));
 
                 for attr in item.attrs {
                     if in_external_macro(cx.sess(), attr.span) {
@@ -326,7 +327,7 @@ impl<'tcx> LateLintPass<'tcx> for Attributes {
                                         match item.kind {
                                             ItemKind::Use(..) => {
                                                 if is_word(lint, sym!(unused_imports))
-                                                    || is_word(lint, sym!(deprecated))
+                                                    || is_word(lint, sym::deprecated)
                                                     || is_word(lint, sym!(unreachable_pub))
                                                     || is_word(lint, sym!(unused))
                                                     || extract_clippy_lint(lint)
@@ -411,8 +412,7 @@ fn check_clippy_lint_names(cx: &LateContext<'_>, ident: &str, items: &[NestedMet
     let lint_store = cx.lints();
     for lint in items {
         if let Some(lint_name) = extract_clippy_lint(lint) {
-            if let CheckLintNameResult::Tool(Err((None, _))) =
-                lint_store.check_lint_name(&lint_name, Some(sym!(clippy)))
+            if let CheckLintNameResult::Tool(Err((None, _))) = lint_store.check_lint_name(&lint_name, Some(sym::clippy))
             {
                 span_lint_and_then(
                     cx,
@@ -529,10 +529,10 @@ fn check_attrs(cx: &LateContext<'_>, span: Span, name: Symbol, attrs: &[Attribut
 
     for attr in attrs {
         if let Some(values) = attr.meta_item_list() {
-            if values.len() != 1 || !attr.has_name(sym!(inline)) {
+            if values.len() != 1 || !attr.has_name(sym::inline) {
                 continue;
             }
-            if is_word(&values[0], sym!(always)) {
+            if is_word(&values[0], sym::always) {
                 span_lint(
                     cx,
                     INLINE_ALWAYS,
@@ -623,12 +623,12 @@ fn check_empty_line_after_outer_attr(cx: &EarlyContext<'_>, item: &rustc_ast::It
 fn check_deprecated_cfg_attr(cx: &EarlyContext<'_>, attr: &Attribute) {
     if_chain! {
         // check cfg_attr
-        if attr.has_name(sym!(cfg_attr));
+        if attr.has_name(sym::cfg_attr);
         if let Some(items) = attr.meta_item_list();
         if items.len() == 2;
         // check for `rustfmt`
         if let Some(feature_item) = items[0].meta_item();
-        if feature_item.has_name(sym!(rustfmt));
+        if feature_item.has_name(sym::rustfmt);
         // check for `rustfmt_skip` and `rustfmt::skip`
         if let Some(skip_item) = &items[1].meta_item();
         if skip_item.has_name(sym!(rustfmt_skip)) ||
@@ -690,7 +690,7 @@ fn check_mismatched_target_os(cx: &EarlyContext<'_>, attr: &Attribute) {
     }
 
     if_chain! {
-        if attr.has_name(sym!(cfg));
+        if attr.has_name(sym::cfg);
         if let Some(list) = attr.meta_item_list();
         let mismatched = find_mismatched_target_os(&list);
         if !mismatched.is_empty();

src/tools/clippy/clippy_lints/src/booleans.rs

@@ -11,6 +11,7 @@ use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::map::Map;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
+use rustc_span::sym;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for boolean expressions that can be written more
@@ -253,8 +254,8 @@ fn simplify_not(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<String> {
         },
         ExprKind::MethodCall(path, _, args, _) if args.len() == 1 => {
             let type_of_receiver = cx.typeck_results().expr_ty(&args[0]);
-            if !is_type_diagnostic_item(cx, type_of_receiver, sym!(option_type))
-                && !is_type_diagnostic_item(cx, type_of_receiver, sym!(result_type))
+            if !is_type_diagnostic_item(cx, type_of_receiver, sym::option_type)
+                && !is_type_diagnostic_item(cx, type_of_receiver, sym::result_type)
             {
                 return None;
             }

src/tools/clippy/clippy_lints/src/bytecount.rs

@@ -8,6 +8,7 @@ use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::sym;
 use rustc_span::Symbol;
 
 declare_clippy_lint! {
@@ -68,7 +69,7 @@ impl<'tcx> LateLintPass<'tcx> for ByteCount {
                         let haystack = if let ExprKind::MethodCall(ref path, _, ref args, _) =
                                 filter_args[0].kind {
                             let p = path.ident.name;
-                            if (p == sym!(iter) || p == sym!(iter_mut)) && args.len() == 1 {
+                            if (p == sym::iter || p == sym!(iter_mut)) && args.len() == 1 {
                                 &args[0]
                             } else {
                                 &filter_args[0]

src/tools/clippy/clippy_lints/src/cognitive_complexity.rs

@@ -7,7 +7,7 @@ use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::hir::map::Map;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
-use rustc_span::BytePos;
+use rustc_span::{sym, BytePos};
 
 use crate::utils::{is_type_diagnostic_item, snippet_opt, span_lint_and_help, LimitStack};
 
@@ -61,7 +61,7 @@ impl CognitiveComplexity {
         helper.visit_expr(expr);
         let CCHelper { cc, returns } = helper;
         let ret_ty = cx.typeck_results().node_type(expr.hir_id);
-        let ret_adjust = if is_type_diagnostic_item(cx, ret_ty, sym!(result_type)) {
+        let ret_adjust = if is_type_diagnostic_item(cx, ret_ty, sym::result_type) {
             returns
         } else {
             #[allow(clippy::integer_division)]
@@ -123,7 +123,7 @@ impl<'tcx> LateLintPass<'tcx> for CognitiveComplexity {
         hir_id: HirId,
     ) {
         let def_id = cx.tcx.hir().local_def_id(hir_id);
-        if !cx.tcx.has_attr(def_id.to_def_id(), sym!(test)) {
+        if !cx.tcx.has_attr(def_id.to_def_id(), sym::test) {
             self.check(cx, kind, decl, body, span);
         }
     }