Merge branch 'master' into unit-arg

Author: tnielens

.cargo/config

@@ -1,6 +1,6 @@
 [alias]
 uitest = "test --test compile-test"
-dev = "run --package clippy_dev --bin clippy_dev --manifest-path clippy_dev/Cargo.toml --"
+dev = "run --target-dir clippy_dev/target --package clippy_dev --bin clippy_dev --manifest-path clippy_dev/Cargo.toml --"
 
 [build]
 rustflags = ["-Zunstable-options"]

.github/workflows/clippy.yml

@@ -92,6 +92,13 @@ jobs:
       env:
         OS: ${{ runner.os }}
 
+    - name: Test cargo dev new lint
+      run: |
+        cargo dev new_lint --name new_early_pass --pass early
+        cargo dev new_lint --name new_late_pass --pass late
+        cargo check
+        git reset --hard HEAD
+
     # Cleanup
     - name: Run cargo-cache --autoclean
       run: |

CHANGELOG.md

@@ -6,11 +6,113 @@ document.
 
 ## Unreleased / In Rust Nightly
 
-[c2c07fa...master](https://github.com/rust-lang/rust-clippy/compare/c2c07fa...master)
+[09bd400...master](https://github.com/rust-lang/rust-clippy/compare/09bd400...master)
+
+## Rust 1.47
+
+Current beta, release 2020-10-08
+
+[c2c07fa...09bd400](https://github.com/rust-lang/rust-clippy/compare/c2c07fa...09bd400)
+
+### New lints
+
+* [`derive_ord_xor_partial_ord`] [#5848](https://github.com/rust-lang/rust-clippy/pull/5848)
+* [`trait_duplication_in_bounds`] [#5852](https://github.com/rust-lang/rust-clippy/pull/5852)
+* [`map_identity`] [#5694](https://github.com/rust-lang/rust-clippy/pull/5694)
+* [`unit_return_expecting_ord`] [#5737](https://github.com/rust-lang/rust-clippy/pull/5737)
+* [`pattern_type_mismatch`] [#4841](https://github.com/rust-lang/rust-clippy/pull/4841)
+* [`repeat_once`] [#5773](https://github.com/rust-lang/rust-clippy/pull/5773)
+* [`same_item_push`] [#5825](https://github.com/rust-lang/rust-clippy/pull/5825)
+* [`needless_arbitrary_self_type`] [#5869](https://github.com/rust-lang/rust-clippy/pull/5869)
+* [`match_like_matches_macro`] [#5769](https://github.com/rust-lang/rust-clippy/pull/5769)
+* [`stable_sort_primitive`] [#5809](https://github.com/rust-lang/rust-clippy/pull/5809)
+* [`blanket_clippy_restriction_lints`] [#5750](https://github.com/rust-lang/rust-clippy/pull/5750)
+* [`option_if_let_else`] [#5301](https://github.com/rust-lang/rust-clippy/pull/5301)
+
+### Moves and Deprecations
+
+* Deprecate [`regex_macro`] lint
+  [#5760](https://github.com/rust-lang/rust-clippy/pull/5760)
+* Move [`range_minus_one`] to `pedantic`
+  [#5752](https://github.com/rust-lang/rust-clippy/pull/5752)
+
+### Enhancements
+
+* Improve [`needless_collect`] by catching `collect` calls followed by `iter` or `into_iter` calls
+  [#5837](https://github.com/rust-lang/rust-clippy/pull/5837)
+* [`panic`], [`todo`], [`unimplemented`] and [`unreachable`] now detect calls with formatting
+  [#5811](https://github.com/rust-lang/rust-clippy/pull/5811)
+* Detect more cases of [`suboptimal_flops`] and [`imprecise_flops`]
+  [#5443](https://github.com/rust-lang/rust-clippy/pull/5443)
+* Handle asymmetrical implementations of `PartialEq` in [`cmp_owned`]
+  [#5701](https://github.com/rust-lang/rust-clippy/pull/5701)
+* Make it possible to allow [`unsafe_derive_deserialize`]
+  [#5870](https://github.com/rust-lang/rust-clippy/pull/5870)
+* Catch `ord.min(a).max(b)` where a < b in [`min_max`]
+  [#5871](https://github.com/rust-lang/rust-clippy/pull/5871)
+* Make [`clone_on_copy`] suggestion machine applicable
+  [#5745](https://github.com/rust-lang/rust-clippy/pull/5745)
+* Enable [`len_zero`] on ranges now that `is_empty` is stable on them
+  [#5961](https://github.com/rust-lang/rust-clippy/pull/5961)
+
+### False Positive Fixes
+
+* Avoid triggering [`or_fun_call`] with const fns that take no arguments
+  [#5889](https://github.com/rust-lang/rust-clippy/pull/5889)
+* Fix [`redundant_closure_call`] false positive for closures that have multiple calls
+  [#5800](https://github.com/rust-lang/rust-clippy/pull/5800)
+* Don't lint cases involving `ManuallyDrop` in [`redundant_clone`]
+  [#5824](https://github.com/rust-lang/rust-clippy/pull/5824)
+* Treat a single expression the same as a single statement in the 2nd arm of a match in [`single_match_else`]
+  [#5771](https://github.com/rust-lang/rust-clippy/pull/5771)
+* Don't trigger [`unnested_or_patterns`] if the feature `or_patterns` is not enabled
+  [#5758](https://github.com/rust-lang/rust-clippy/pull/5758)
+* Avoid linting if key borrows in [`unnecessary_sort_by`]
+  [#5756](https://github.com/rust-lang/rust-clippy/pull/5756)
+* Consider `Try` impl for `Poll` when generating suggestions in [`try_err`]
+  [#5857](https://github.com/rust-lang/rust-clippy/pull/5857)
+* Take input lifetimes into account in `manual_async_fn`
+  [#5859](https://github.com/rust-lang/rust-clippy/pull/5859)
+* Fix multiple false positives in [`type_repetition_in_bounds`] and add a configuration option
+  [#5761](https://github.com/rust-lang/rust-clippy/pull/5761)
+* Limit the [`suspicious_arithmetic_impl`] lint to one binary operation
+  [#5820](https://github.com/rust-lang/rust-clippy/pull/5820)
+
+### Suggestion Fixes/Improvements
+
+* Improve readability of [`shadow_unrelated`] suggestion by truncating the RHS snippet
+  [#5788](https://github.com/rust-lang/rust-clippy/pull/5788)
+* Suggest `filter_map` instead of `flat_map` when mapping to `Option` in [`map_flatten`]
+  [#5846](https://github.com/rust-lang/rust-clippy/pull/5846)
+* Ensure suggestion is shown correctly for long method call chains in [`iter_nth_zero`]
+  [#5793](https://github.com/rust-lang/rust-clippy/pull/5793)
+* Drop borrow operator in suggestions of [`redundant_pattern_matching`]
+  [#5815](https://github.com/rust-lang/rust-clippy/pull/5815)
+* Add suggestion for [`iter_skip_next`]
+  [#5843](https://github.com/rust-lang/rust-clippy/pull/5843)
+* Improve [`collapsible_if`] fix suggestion
+  [#5732](https://github.com/rust-lang/rust-clippy/pull/5732)
+
+### ICE Fixes
+
+* Fix ICE caused by [`needless_collect`]
+  [#5877](https://github.com/rust-lang/rust-clippy/pull/5877)
+* Fix ICE caused by [`unnested_or_patterns`]
+  [#5784](https://github.com/rust-lang/rust-clippy/pull/5784)
+
+### Documentation Improvements
+
+* Fix grammar of [`await_holding_lock`] documentation
+  [#5748](https://github.com/rust-lang/rust-clippy/pull/5748)
+
+### Others
+
+* Make lints adhere to the rustc dev guide
+  [#5888](https://github.com/rust-lang/rust-clippy/pull/5888)
 
 ## Rust 1.46
 
-Current beta, release 2020-08-27
+Current stable, released 2020-08-27
 
 [7ea7cd1...c2c07fa](https://github.com/rust-lang/rust-clippy/compare/7ea7cd1...c2c07fa)
 
@@ -72,7 +174,7 @@ Current beta, release 2020-08-27
 
 ## Rust 1.45
 
-Current stable, released 2020-07-16
+Released 2020-07-16
 
 [891e1a8...7ea7cd1](https://github.com/rust-lang/rust-clippy/compare/891e1a8...7ea7cd1)
 
@@ -1498,6 +1600,7 @@ Released 2018-09-13
 [`float_arithmetic`]: https://rust-lang.github.io/rust-clippy/master/index.html#float_arithmetic
 [`float_cmp`]: https://rust-lang.github.io/rust-clippy/master/index.html#float_cmp
 [`float_cmp_const`]: https://rust-lang.github.io/rust-clippy/master/index.html#float_cmp_const
+[`float_equality_without_abs`]: https://rust-lang.github.io/rust-clippy/master/index.html#float_equality_without_abs
 [`fn_address_comparisons`]: https://rust-lang.github.io/rust-clippy/master/index.html#fn_address_comparisons
 [`fn_params_excessive_bools`]: https://rust-lang.github.io/rust-clippy/master/index.html#fn_params_excessive_bools
 [`fn_to_numeric_cast`]: https://rust-lang.github.io/rust-clippy/master/index.html#fn_to_numeric_cast
@@ -1777,6 +1880,7 @@ Released 2018-09-13
 [`unused_label`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_label
 [`unused_self`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_self
 [`unused_unit`]: https://rust-lang.github.io/rust-clippy/master/index.html#unused_unit
+[`unwrap_in_result`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_in_result
 [`unwrap_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#unwrap_used
 [`use_debug`]: https://rust-lang.github.io/rust-clippy/master/index.html#use_debug
 [`use_self`]: https://rust-lang.github.io/rust-clippy/master/index.html#use_self

CONTRIBUTING.md

@@ -189,6 +189,35 @@ Clippy in the `rust-lang/rust` repository.
 For general information about `subtree`s in the Rust repository see [Rust's
 `CONTRIBUTING.md`][subtree].
 
+### Patching git-subtree to work with big repos
+
+Currently there's a bug in `git-subtree` that prevents it from working properly
+with the [`rust-lang/rust`] repo. There's an open PR to fix that, but it's stale.
+Before continuing with the following steps, we need to manually apply that fix to
+our local copy of `git-subtree`.
+
+You can get the patched version of `git-subtree` from [here][gitgitgadget-pr].
+Put this file under `/usr/lib/git-core` (taking a backup of the previous file)
+and make sure it has the proper permissions:
+
+```bash
+sudo cp --backup /path/to/patched/git-subtree.sh /usr/lib/git-core/git-subtree
+sudo chmod --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
+sudo chown --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
+```
+
+_Note:_ The first time running `git subtree push` a cache has to be built. This
+involves going through the complete Clippy history once. For this you have to
+increase the stack limit though, which you can do with `ulimit -s 60000`.
+Make sure to run the `ulimit` command from the same session you call git subtree.
+
+_Note:_ If you are a Debian user, `dash` is the shell used by default for scripts instead of `sh`.
+This shell has a hardcoded recursion limit set to 1000. In order to make this process work,
+you need to force the script to run `bash` instead. You can do this by editing the first
+line of the `git-subtree` script and changing `sh` to `bash`.
+
+### Performing the sync
+
 Here is a TL;DR version of the sync process (all of the following commands have
 to be run inside the `rust` directory):
 
@@ -198,6 +227,7 @@ to be run inside the `rust` directory):
     # Make sure to change `your-github-name` to your github name in the following command
     git subtree push -P src/tools/clippy [email protected]:your-github-name/rust-clippy sync-from-rust
     ```
+
     _Note:_ This will directly push to the remote repository. You can also push
     to your local copy by replacing the remote address with `/path/to/rust-clippy`
     directory.
@@ -213,14 +243,30 @@ to be run inside the `rust` directory):
 3. Open a PR to `rust-lang/rust-clippy` and wait for it to get merged (to
    accelerate the process ping the `@rust-lang/clippy` team in your PR and/or
    ~~annoy~~ ask them in the [Discord] channel.)
-4. Sync the `rust-lang/rust-clippy` master to the rust-copy of Clippy:
+   
+### Syncing back changes in Clippy to [`rust-lang/rust`]
+
+To avoid flooding the [`rust-lang/rust`] PR queue, changes in Clippy's repo are synced back
+in a bi-weekly basis if there's no urgent changes. This is done starting on the day of
+the Rust stable release and then every other week. That way we guarantee that
+every feature in Clippy is available for 2 weeks in nightly, before it can get to beta.
+For reference, the first sync following this cadence was performed the 2020-08-27.
+
+All of the following commands have to be run inside the `rust` directory.
+
+1. Make sure Clippy itself is up-to-date by following the steps outlined in the previous
+section if necessary.
+
+2. Sync the `rust-lang/rust-clippy` master to the rust-copy of Clippy:
     ```bash
     git checkout -b sync-from-clippy
     git subtree pull -P src/tools/clippy https://github.com/rust-lang/rust-clippy master
     ```
-5. Open a PR to [`rust-lang/rust`]
+3. Open a PR to [`rust-lang/rust`]
+
+### Defining remotes
 
-Also, you may want to define remotes, so you don't have to type out the remote
+You may want to define remotes, so you don't have to type out the remote
 addresses on every sync. You can do this with the following commands (these
 commands still have to be run inside the `rust` directory):
 
@@ -241,12 +287,6 @@ You can then sync with the remote names from above, e.g.:
 $ git subtree push -P src/tools/clippy clippy-local sync-from-rust
 ```
 
-_Note:_ The first time running `git subtree push` a cache has to be built. This
-involves going through the complete Clippy history once. For this you have to
-increase the stack limit though, which you can do with `ulimit -s 60000`. For
-this to work, you will need the fix of `git subtree` available
-[here][gitgitgadget-pr].
-
 [gitgitgadget-pr]: https://github.com/gitgitgadget/git/pull/493
 [subtree]: https://rustc-dev-guide.rust-lang.org/contributing.html#external-dependencies-subtree
 [`rust-lang/rust`]: https://github.com/rust-lang/rust

clippy_dev/src/new_lint.rs

@@ -47,7 +47,7 @@ pub fn create(pass: Option<&str>, lint_name: Option<&str>, category: Option<&str
 fn create_lint(lint: &LintData) -> io::Result<()> {
     let (pass_type, pass_lifetimes, pass_import, context_import) = match lint.pass {
         "early" => ("EarlyLintPass", "", "use rustc_ast::ast::*;", "EarlyContext"),
-        "late" => ("LateLintPass", "<'_, '_>", "use rustc_hir::*;", "LateContext"),
+        "late" => ("LateLintPass", "<'_>", "use rustc_hir::*;", "LateContext"),
         _ => {
             unreachable!("`pass_type` should only ever be `early` or `late`!");
         },

clippy_lints/src/float_equality_without_abs.rs

@@ -0,0 +1,110 @@
+use crate::utils::{match_qpath, paths, span_lint_and_then, sugg};
+use if_chain::if_chain;
+use rustc_ast::util::parser::AssocOp;
+use rustc_errors::Applicability;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty;
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Spanned;
+
+declare_clippy_lint! {
+    /// **What it does:** Checks for statements of the form `(a - b) < f32::EPSILON` or
+     /// `(a - b) < f64::EPSILON`. Notes the missing `.abs()`.
+     ///
+     /// **Why is this bad?** The code without `.abs()` is more likely to have a bug.
+     ///
+     /// **Known problems:** If the user can ensure that b is larger than a, the `.abs()` is
+     /// technically unneccessary. However, it will make the code more robust and doesn't have any
+     /// large performance implications. If the abs call was deliberately left out for performance
+     /// reasons, it is probably better to state this explicitly in the code, which then can be done
+     /// with an allow.
+     ///
+     /// **Example:**
+     ///
+     /// ```rust
+     /// pub fn is_roughly_equal(a: f32, b: f32) -> bool {
+     ///     (a - b) < f32::EPSILON
+     /// }
+     /// ```
+     /// Use instead:
+     /// ```rust
+     /// pub fn is_roughly_equal(a: f32, b: f32) -> bool {
+     ///     (a - b).abs() < f32::EPSILON
+     /// }
+     /// ```
+    pub FLOAT_EQUALITY_WITHOUT_ABS,
+    correctness,
+    "float equality check without `.abs()`"
+}
+
+declare_lint_pass!(FloatEqualityWithoutAbs => [FLOAT_EQUALITY_WITHOUT_ABS]);
+
+impl<'tcx> LateLintPass<'tcx> for FloatEqualityWithoutAbs {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
+        let lhs;
+        let rhs;
+
+        // check if expr is a binary expression with a lt or gt operator
+        if let ExprKind::Binary(op, ref left, ref right) = expr.kind {
+            match op.node {
+                BinOpKind::Lt => {
+                    lhs = left;
+                    rhs = right;
+                },
+                BinOpKind::Gt => {
+                    lhs = right;
+                    rhs = left;
+                },
+                _ => return,
+            };
+        } else {
+            return;
+        }
+
+        if_chain! {
+
+            // left hand side is a substraction
+            if let ExprKind::Binary(
+                Spanned {
+                    node: BinOpKind::Sub,
+                    ..
+                },
+                val_l,
+                val_r,
+            ) = lhs.kind;
+
+            // right hand side matches either f32::EPSILON or f64::EPSILON
+            if let ExprKind::Path(ref epsilon_path) = rhs.kind;
+            if match_qpath(epsilon_path, &paths::F32_EPSILON) || match_qpath(epsilon_path, &paths::F64_EPSILON);
+
+            // values of the substractions on the left hand side are of the type float
+            let t_val_l = cx.typeck_results().expr_ty(val_l);
+            let t_val_r = cx.typeck_results().expr_ty(val_r);
+            if let ty::Float(_) = t_val_l.kind;
+            if let ty::Float(_) = t_val_r.kind;
+
+            then {
+                let sug_l = sugg::Sugg::hir(cx, &val_l, "..");
+                let sug_r = sugg::Sugg::hir(cx, &val_r, "..");
+                // format the suggestion
+                let suggestion = format!("{}.abs()", sugg::make_assoc(AssocOp::Subtract, &sug_l, &sug_r).maybe_par());
+                // spans the lint
+                span_lint_and_then(
+                    cx,
+                    FLOAT_EQUALITY_WITHOUT_ABS,
+                    expr.span,
+                    "float equality check without `.abs()`",
+                    | diag | {
+                        diag.span_suggestion(
+                            lhs.span,
+                            "add `.abs()`",
+                            suggestion,
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                );
+            }
+        }
+    }
+}