upgrade equatable_if_let to style

CHANGELOG.md

@@ -2843,6 +2843,7 @@ Released 2018-09-13
 [`enum_variant_names`]: https://rust-lang.github.io/rust-clippy/master/index.html#enum_variant_names
 [`eq_op`]: https://rust-lang.github.io/rust-clippy/master/index.html#eq_op
 [`equatable_if_let`]: https://rust-lang.github.io/rust-clippy/master/index.html#equatable_if_let
+[`equatable_matches`]: https://rust-lang.github.io/rust-clippy/master/index.html#equatable_matches
 [`erasing_op`]: https://rust-lang.github.io/rust-clippy/master/index.html#erasing_op
 [`eval_order_dependence`]: https://rust-lang.github.io/rust-clippy/master/index.html#eval_order_dependence
 [`excessive_precision`]: https://rust-lang.github.io/rust-clippy/master/index.html#excessive_precision

clippy_lints/src/casts/cast_lossless.rs

@@ -65,17 +65,15 @@ fn should_lint(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to
 
         (true, false) => {
             let from_nbits = utils::int_ty_to_nbits(cast_from, cx.tcx);
-            let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind() {
+            let to_nbits = if cast_to.kind() == &ty::Float(FloatTy::F32) {
                 32
             } else {
                 64
             };
             from_nbits < to_nbits
         },
 
-        (_, _) => {
-            matches!(cast_from.kind(), ty::Float(FloatTy::F32)) && matches!(cast_to.kind(), ty::Float(FloatTy::F64))
-        },
+        (_, _) => cast_from.kind() == &ty::Float(FloatTy::F32) && cast_to.kind() == &ty::Float(FloatTy::F64),
     }
 }
 

clippy_lints/src/casts/cast_possible_truncation.rs

@@ -48,9 +48,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>,
         },
 
         (_, _) => {
-            if matches!(cast_from.kind(), &ty::Float(FloatTy::F64))
-                && matches!(cast_to.kind(), &ty::Float(FloatTy::F32))
-            {
+            if cast_from.kind() == &ty::Float(FloatTy::F64) && cast_to.kind() == &ty::Float(FloatTy::F32) {
                 "casting `f64` to `f32` may truncate the value".to_string()
             } else {
                 return;

clippy_lints/src/equatable_if_let.rs

@@ -1,16 +1,23 @@
-use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::source::snippet_with_context;
+use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
 use clippy_utils::ty::implements_trait;
+use clippy_utils::{diagnostics::span_lint_and_sugg, higher::MatchesExpn};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{Expr, ExprKind, Pat, PatKind};
-use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::Ty;
-use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_hir::{
+    def::{DefKind, Res},
+    Arm, Expr, ExprKind, Pat, PatKind, QPath,
+};
+use rustc_lint::{LateContext, LateLintPass, Lint};
+use rustc_middle::ty::{Adt, Ty};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::{Span, SyntaxContext};
+
+use crate::utils::conf::EquatablePatternLevel;
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for pattern matchings that can be expressed using equality.
+    /// Checks for `if let <pat> = <expr>` (and `while let` and similars) that can be expressed
+    /// using `if <expr> == <pat>`.
     ///
     /// ### Why is this bad?
     ///
@@ -33,68 +40,225 @@ declare_clippy_lint! {
     /// }
     /// ```
     pub EQUATABLE_IF_LET,
-    nursery,
-    "using pattern matching instead of equality"
+    style,
+    "using if let instead of if with a equality condition"
 }
 
-declare_lint_pass!(PatternEquality => [EQUATABLE_IF_LET]);
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for `matches!(<expr>, <pat>)` that can be expressed
+    /// using `<expr> == <pat>`.
+    ///
+    /// ### Why is this bad?
+    ///
+    /// It is less concise and less clear.
+    ///
+    /// ### Example
+    /// ```rust,ignore
+    /// let condition = matches!(x, Some(2));
+    /// ```
+    /// Should be written
+    /// ```rust,ignore
+    /// let condition = x == Some(2);
+    /// ```
+    pub EQUATABLE_MATCHES,
+    pedantic,
+    "using `matches!` instead of equality"
+}
+
+pub struct PatternEquality {
+    level: EquatablePatternLevel,
+}
 
-/// detects if pattern matches just one thing
-fn unary_pattern(pat: &Pat<'_>) -> bool {
-    fn array_rec(pats: &[Pat<'_>]) -> bool {
-        pats.iter().all(unary_pattern)
+impl PatternEquality {
+    pub fn new(level: EquatablePatternLevel) -> PatternEquality {
+        PatternEquality { level }
     }
-    match &pat.kind {
-        PatKind::Slice(_, _, _) | PatKind::Range(_, _, _) | PatKind::Binding(..) | PatKind::Wild | PatKind::Or(_) => {
+}
+
+impl_lint_pass!(PatternEquality => [EQUATABLE_IF_LET, EQUATABLE_MATCHES]);
+
+fn equatable_pattern(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
+    fn array_rec(cx: &LateContext<'_>, pats: &[Pat<'_>]) -> bool {
+        pats.iter().all(|x| equatable_pattern(cx, x))
+    }
+    fn is_derived(cx: &LateContext<'_>, pat: &Pat<'_>) -> bool {
+        let ty = cx.typeck_results().pat_ty(pat);
+        if let Some(def_id) = cx.tcx.lang_items().structural_peq_trait() {
+            implements_trait(cx, ty, def_id, &[ty.into()])
+        } else {
             false
+        }
+    }
+    match &pat.kind {
+        PatKind::Slice(a, None, []) => array_rec(cx, a),
+        PatKind::Struct(_, a, etc) => !etc && is_derived(cx, pat) && a.iter().all(|x| equatable_pattern(cx, x.pat)),
+        PatKind::Tuple(a, etc) => !etc.is_some() && array_rec(cx, a),
+        PatKind::TupleStruct(_, a, etc) => !etc.is_some() && is_derived(cx, pat) && array_rec(cx, a),
+        PatKind::Ref(x, _) | PatKind::Box(x) => equatable_pattern(cx, x),
+        PatKind::Path(QPath::Resolved(_, b)) => match b.res {
+            Res::Def(DefKind::Const, _) => true,
+            _ => is_derived(cx, pat),
         },
-        PatKind::Struct(_, a, etc) => !etc && a.iter().all(|x| unary_pattern(x.pat)),
-        PatKind::Tuple(a, etc) | PatKind::TupleStruct(_, a, etc) => !etc.is_some() && array_rec(a),
-        PatKind::Ref(x, _) | PatKind::Box(x) => unary_pattern(x),
-        PatKind::Path(_) | PatKind::Lit(_) => true,
+        PatKind::Path(_) => is_derived(cx, pat),
+        PatKind::Lit(_) => true,
+        PatKind::Slice(..) | PatKind::Range(..) | PatKind::Binding(..) | PatKind::Wild | PatKind::Or(_) => false,
     }
 }
 
-fn is_structural_partial_eq(cx: &LateContext<'tcx>, ty: Ty<'tcx>, other: Ty<'tcx>) -> bool {
+fn is_partial_eq(cx: &LateContext<'tcx>, t1: Ty<'tcx>, t2: Ty<'tcx>) -> bool {
     if let Some(def_id) = cx.tcx.lang_items().eq_trait() {
-        implements_trait(cx, ty, def_id, &[other.into()])
+        implements_trait(cx, t1, def_id, &[t2.into()])
     } else {
         false
     }
 }
 
+fn pat_to_string(
+    cx: &LateContext<'tcx>,
+    app: &mut Applicability,
+    pat: &Pat<'_>,
+    goal: Ty<'_>,
+    ctxt: SyntaxContext,
+) -> Option<String> {
+    fn inner(
+        cx: &LateContext<'tcx>,
+        app: &mut Applicability,
+        pat: &Pat<'_>,
+        goal: Ty<'_>,
+        r: &mut String,
+        ctxt: SyntaxContext,
+    ) -> bool {
+        let ty = cx.typeck_results().pat_ty(pat);
+        if ty == goal {
+            match &pat.kind {
+                PatKind::TupleStruct(q, ..) | PatKind::Struct(q, ..) => {
+                    let (adt_def, generic_args) = if let Adt(x, y) = ty.kind() {
+                        (x, y)
+                    } else {
+                        return false; // shouldn't happen
+                    };
+                    let path = if let QPath::Resolved(.., p) = q {
+                        p
+                    } else {
+                        return false; // give up
+                    };
+                    let var = adt_def.variant_of_res(path.res);
+                    match &pat.kind {
+                        PatKind::TupleStruct(_, params, _) => {
+                            *r += &*snippet_with_applicability(cx, path.span, "..", app);
+                            *r += "(";
+                            for (i, (p, f)) in params.iter().zip(var.fields.iter()).enumerate() {
+                                if i != 0 {
+                                    *r += ", ";
+                                }
+                                inner(cx, app, p, f.ty(cx.tcx, generic_args), r, ctxt);
+                            }
+                            *r += ")";
+                        },
+                        PatKind::Struct(_, fields, _) => {
+                            *r += &*snippet_with_applicability(cx, path.span, "..", app);
+                            *r += " { ";
+                            for (i, p) in fields.iter().enumerate() {
+                                if i != 0 {
+                                    *r += ", ";
+                                }
+                                *r += &*snippet_with_applicability(cx, p.ident.span, "..", app);
+                                *r += ": ";
+                                if let Some(x) = var.fields.iter().find(|f| f.ident == p.ident) {
+                                    inner(cx, app, p.pat, x.ty(cx.tcx, generic_args), r, ctxt);
+                                } else {
+                                    return false; // won't happen
+                                }
+                            }
+                            *r += " }";
+                        },
+                        _ => return false, // won't happen
+                    }
+                },
+                _ => {
+                    *r += &*snippet_with_context(cx, pat.span, ctxt, "..", app).0;
+                },
+            }
+            return true;
+        }
+        if goal.is_ref() {
+            if let Some(tam) = goal.builtin_deref(true) {
+                *r += "&";
+                return inner(cx, app, pat, tam.ty, r, ctxt);
+            }
+        }
+        false
+    }
+    let mut r = "".to_string();
+    if let PatKind::Struct(..) = pat.kind {
+        r += "(";
+    }
+    let success = inner(cx, app, pat, goal, &mut r, ctxt);
+    if let PatKind::Struct(..) = pat.kind {
+        r += ")";
+    }
+    if !success {
+        return None;
+    }
+    Some(r)
+}
+
+fn level_contains(level: EquatablePatternLevel, pat: &Pat<'_>) -> bool {
+    match level {
+        EquatablePatternLevel::Primitive => matches!(pat.kind, PatKind::Lit(_)),
+        EquatablePatternLevel::Simple => matches!(pat.kind, PatKind::Lit(_) | PatKind::Path(_)),
+        EquatablePatternLevel::All => true,
+    }
+}
+
+fn emit_lint(
+    cx: &LateContext<'tcx>,
+    pat: &Pat<'_>,
+    exp: &Expr<'_>,
+    ctxt: SyntaxContext,
+    span: Span,
+    lint: &'static Lint,
+    level: EquatablePatternLevel,
+) {
+    if_chain! {
+        if equatable_pattern(cx, pat);
+        if level_contains(level, pat);
+        let exp_ty = cx.typeck_results().expr_ty(exp);
+        if is_partial_eq(cx, exp_ty, exp_ty);
+        let mut app = Applicability::MachineApplicable;
+        if let Some(pat_str) = pat_to_string(cx, &mut app, pat, exp_ty, ctxt);
+        then {
+            let exp_str = snippet_with_context(cx, exp.span, ctxt, "..", &mut app).0;
+            span_lint_and_sugg(
+                cx,
+                lint,
+                span,
+                "this pattern matching can be expressed using equality",
+                "try",
+                format!(
+                    "{} == {}",
+                    exp_str,
+                    pat_str,
+                ),
+                app,
+            );
+        }
+    }
+}
+
 impl<'tcx> LateLintPass<'tcx> for PatternEquality {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
-        if_chain! {
-            if let ExprKind::Let(pat, exp, _) = expr.kind;
-            if unary_pattern(pat);
-            let exp_ty = cx.typeck_results().expr_ty(exp);
-            let pat_ty = cx.typeck_results().pat_ty(pat);
-            if is_structural_partial_eq(cx, exp_ty, pat_ty);
-            then {
-
-                let mut applicability = Applicability::MachineApplicable;
-                let pat_str = match pat.kind {
-                    PatKind::Struct(..) => format!(
-                        "({})",
-                        snippet_with_context(cx, pat.span, expr.span.ctxt(), "..", &mut applicability).0,
-                    ),
-                    _ => snippet_with_context(cx, pat.span, expr.span.ctxt(), "..", &mut applicability).0.to_string(),
-                };
-                span_lint_and_sugg(
-                    cx,
-                    EQUATABLE_IF_LET,
-                    expr.span,
-                    "this pattern matching can be expressed using equality",
-                    "try",
-                    format!(
-                        "{} == {}",
-                        snippet_with_context(cx, exp.span, expr.span.ctxt(), "..", &mut applicability).0,
-                        pat_str,
-                    ),
-                    applicability,
-                );
-            }
+        if let ExprKind::Let(pat, exp, _) = expr.kind {
+            emit_lint(cx, pat, exp, expr.span.ctxt(), expr.span, EQUATABLE_IF_LET, self.level);
+        }
+        if let Some(MatchesExpn {
+            call_site,
+            arm: Arm { pat, guard: None, .. },
+            exp,
+        }) = MatchesExpn::parse(expr)
+        {
+            emit_lint(cx, pat, exp, expr.span.ctxt(), call_site, EQUATABLE_MATCHES, self.level);
         }
     }
 }

clippy_lints/src/lib.register_all.rs

@@ -51,6 +51,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
     LintId::of(enum_variants::MODULE_INCEPTION),
     LintId::of(eq_op::EQ_OP),
     LintId::of(eq_op::OP_REF),
+    LintId::of(equatable_if_let::EQUATABLE_IF_LET),
     LintId::of(erasing_op::ERASING_OP),
     LintId::of(escape::BOXED_LOCAL),
     LintId::of(eta_reduction::REDUNDANT_CLOSURE),

clippy_lints/src/lib.register_lints.rs

@@ -118,6 +118,7 @@ store.register_lints(&[
     eq_op::EQ_OP,
     eq_op::OP_REF,
     equatable_if_let::EQUATABLE_IF_LET,
+    equatable_if_let::EQUATABLE_MATCHES,
     erasing_op::ERASING_OP,
     escape::BOXED_LOCAL,
     eta_reduction::REDUNDANT_CLOSURE,

clippy_lints/src/lib.register_nursery.rs

@@ -8,7 +8,6 @@ store.register_group(true, "clippy::nursery", Some("clippy_nursery"), vec![
     LintId::of(copies::BRANCHES_SHARING_CODE),
     LintId::of(disallowed_method::DISALLOWED_METHOD),
     LintId::of(disallowed_type::DISALLOWED_TYPE),
-    LintId::of(equatable_if_let::EQUATABLE_IF_LET),
     LintId::of(fallible_impl_from::FALLIBLE_IMPL_FROM),
     LintId::of(floating_point_arithmetic::IMPRECISE_FLOPS),
     LintId::of(floating_point_arithmetic::SUBOPTIMAL_FLOPS),

clippy_lints/src/lib.register_pedantic.rs

@@ -28,6 +28,7 @@ store.register_group(true, "clippy::pedantic", Some("clippy_pedantic"), vec![
     LintId::of(doc::MISSING_PANICS_DOC),
     LintId::of(empty_enum::EMPTY_ENUM),
     LintId::of(enum_variants::MODULE_NAME_REPETITIONS),
+    LintId::of(equatable_if_let::EQUATABLE_MATCHES),
     LintId::of(eta_reduction::REDUNDANT_CLOSURE_FOR_METHOD_CALLS),
     LintId::of(excessive_bools::FN_PARAMS_EXCESSIVE_BOOLS),
     LintId::of(excessive_bools::STRUCT_EXCESSIVE_BOOLS),

clippy_lints/src/lib.register_style.rs

@@ -20,6 +20,7 @@ store.register_group(true, "clippy::style", Some("clippy_style"), vec![
     LintId::of(enum_variants::ENUM_VARIANT_NAMES),
     LintId::of(enum_variants::MODULE_INCEPTION),
     LintId::of(eq_op::OP_REF),
+    LintId::of(equatable_if_let::EQUATABLE_IF_LET),
     LintId::of(eta_reduction::REDUNDANT_CLOSURE),
     LintId::of(float_literal::EXCESSIVE_PRECISION),
     LintId::of(from_over_into::FROM_OVER_INTO),

clippy_lints/src/lib.rs

@@ -722,7 +722,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(future_not_send::FutureNotSend));
     store.register_late_pass(|| Box::new(if_let_mutex::IfLetMutex));
     store.register_late_pass(|| Box::new(if_not_else::IfNotElse));
-    store.register_late_pass(|| Box::new(equatable_if_let::PatternEquality));
+    let equatable_pattern = conf.equatable_pattern;
+    store.register_late_pass(move || Box::new(equatable_if_let::PatternEquality::new(equatable_pattern)));
     store.register_late_pass(|| Box::new(mut_mutex_lock::MutMutexLock));
     store.register_late_pass(|| Box::new(match_on_vec_items::MatchOnVecItems));
     store.register_late_pass(|| Box::new(manual_async_fn::ManualAsyncFn));

clippy_lints/src/manual_async_fn.rs

@@ -165,7 +165,7 @@ fn captures_all_lifetimes(inputs: &[Ty<'_>], output_lifetimes: &[LifetimeName])
     // - There's only one output lifetime bound using `+ '_`
     // - All input lifetimes are explicitly bound to the output
     input_lifetimes.is_empty()
-        || (output_lifetimes.len() == 1 && matches!(output_lifetimes[0], LifetimeName::Underscore))
+        || (output_lifetimes.len() == 1 && output_lifetimes[0] == LifetimeName::Underscore)
         || input_lifetimes
             .iter()
             .all(|in_lt| output_lifetimes.iter().any(|out_lt| in_lt == out_lt))