Extend manual_is_variant_and lint to check for boolean map comparisons (#14646)

samueltardieu · web-flow · commit 551870df9621 · 2025-05-28T10:25:11.000Z
Fixes #14542. changelog: [`manual_is_variant_and`]: Extend to check for boolean map comparisons r? @samueltardieu
diff --git a/clippy_lints/src/methods/manual_is_variant_and.rs b/clippy_lints/src/methods/manual_is_variant_and.rs
@@ -1,18 +1,22 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::get_parent_expr;
 use clippy_utils::msrvs::{self, Msrv};
-use clippy_utils::source::snippet;
+use clippy_utils::source::{snippet, snippet_opt};
 use clippy_utils::ty::is_type_diagnostic_item;
 use rustc_errors::Applicability;
+use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
+use rustc_hir::{BinOpKind, Expr, ExprKind, QPath};
 use rustc_lint::LateContext;
-use rustc_span::{Span, sym};
+use rustc_middle::ty;
+use rustc_span::{BytePos, Span, sym};
 
 use super::MANUAL_IS_VARIANT_AND;
 
-pub(super) fn check<'tcx>(
+pub(super) fn check(
     cx: &LateContext<'_>,
-    expr: &'tcx rustc_hir::Expr<'_>,
-    map_recv: &'tcx rustc_hir::Expr<'_>,
-    map_arg: &'tcx rustc_hir::Expr<'_>,
+    expr: &Expr<'_>,
+    map_recv: &Expr<'_>,
+    map_arg: &Expr<'_>,
     map_span: Span,
     msrv: Msrv,
 ) {
@@ -57,3 +61,57 @@ pub(super) fn check<'tcx>(
         Applicability::MachineApplicable,
     );
 }
+
+fn emit_lint(cx: &LateContext<'_>, op: BinOpKind, parent: &Expr<'_>, method_span: Span, is_option: bool) {
+    if let Some(before_map_snippet) = snippet_opt(cx, parent.span.with_hi(method_span.lo()))
+        && let Some(after_map_snippet) = snippet_opt(cx, method_span.with_lo(method_span.lo() + BytePos(3)))
+    {
+        span_lint_and_sugg(
+            cx,
+            MANUAL_IS_VARIANT_AND,
+            parent.span,
+            format!(
+                "called `.map() {}= {}()`",
+                if op == BinOpKind::Eq { '=' } else { '!' },
+                if is_option { "Some" } else { "Ok" },
+            ),
+            "use",
+            if is_option && op == BinOpKind::Ne {
+                format!("{before_map_snippet}is_none_or{after_map_snippet}",)
+            } else {
+                format!(
+                    "{}{before_map_snippet}{}{after_map_snippet}",
+                    if op == BinOpKind::Eq { "" } else { "!" },
+                    if is_option { "is_some_and" } else { "is_ok_and" },
+                )
+            },
+            Applicability::MachineApplicable,
+        );
+    }
+}
+
+pub(super) fn check_map(cx: &LateContext<'_>, expr: &Expr<'_>) {
+    if let Some(parent_expr) = get_parent_expr(cx, expr)
+        && let ExprKind::Binary(op, left, right) = parent_expr.kind
+        && matches!(op.node, BinOpKind::Eq | BinOpKind::Ne)
+        && op.span.eq_ctxt(expr.span)
+    {
+        // Check `left` and `right` expression in any order, and for `Option` and `Result`
+        for (expr1, expr2) in [(left, right), (right, left)] {
+            for item in [sym::Option, sym::Result] {
+                if let ExprKind::Call(call, ..) = expr1.kind
+                    && let ExprKind::Path(QPath::Resolved(_, path)) = call.kind
+                    && let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), _) = path.res
+                    && let ty = cx.typeck_results().expr_ty(expr1)
+                    && let ty::Adt(adt, args) = ty.kind()
+                    && cx.tcx.is_diagnostic_item(item, adt.did())
+                    && args.type_at(0).is_bool()
+                    && let ExprKind::MethodCall(_, recv, _, span) = expr2.kind
+                    && is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(recv), item)
+                {
+                    return emit_lint(cx, op.node, parent_expr, span, item == sym::Option);
+                }
+            }
+        }
+    }
+}
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
@@ -5203,6 +5203,7 @@ impl Methods {
                         unused_enumerate_index::check(cx, expr, recv, m_arg);
                         map_clone::check(cx, expr, recv, m_arg, self.msrv);
                         map_with_unused_argument_over_ranges::check(cx, expr, recv, m_arg, self.msrv, span);
+                        manual_is_variant_and::check_map(cx, expr);
                         match method_call(recv) {
                             Some((map_name @ (sym::iter | sym::into_iter), recv2, _, _, _)) => {
                                 iter_kv_map::check(cx, map_name, expr, recv2, m_arg, self.msrv);
diff --git a/tests/ui/manual_is_variant_and.fixed b/tests/ui/manual_is_variant_and.fixed
@@ -4,6 +4,44 @@
 #[macro_use]
 extern crate option_helpers;
 
+struct Foo<T>(T);
+
+impl<T> Foo<T> {
+    fn map<F: FnMut(T) -> bool>(self, mut f: F) -> Option<bool> {
+        Some(f(self.0))
+    }
+}
+
+fn foo() -> Option<bool> {
+    Some(true)
+}
+
+macro_rules! some_true {
+    () => {
+        Some(true)
+    };
+}
+macro_rules! some_false {
+    () => {
+        Some(false)
+    };
+}
+
+macro_rules! mac {
+    (some $e:expr) => {
+        Some($e)
+    };
+    (some_map $e:expr) => {
+        Some($e).map(|x| x % 2 == 0)
+    };
+    (map $e:expr) => {
+        $e.map(|x| x % 2 == 0)
+    };
+    (eq $a:expr, $b:expr) => {
+        $a == $b
+    };
+}
+
 #[rustfmt::skip]
 fn option_methods() {
     let opt = Some(1);
@@ -21,13 +59,30 @@ fn option_methods() {
     let _ = opt
         .is_some_and(|x| x > 1);
 
+    let _ = Some(2).is_some_and(|x| x % 2 == 0);
+    //~^ manual_is_variant_and
+    let _ = Some(2).is_none_or(|x| x % 2 == 0);
+    //~^ manual_is_variant_and
+    let _ = Some(2).is_some_and(|x| x % 2 == 0);
+    //~^ manual_is_variant_and
+    let _ = Some(2).is_none_or(|x| x % 2 == 0);
+    //~^ manual_is_variant_and
+
     // won't fix because the return type of the closure is not `bool`
     let _ = opt.map(|x| x + 1).unwrap_or_default();
 
     let opt2 = Some('a');
     let _ = opt2.is_some_and(char::is_alphanumeric); // should lint
     //~^ manual_is_variant_and
     let _ = opt_map!(opt2, |x| x == 'a').unwrap_or_default(); // should not lint
+
+    // Should not lint.
+    let _ = Foo::<u32>(0).map(|x| x % 2 == 0) == Some(true);
+    let _ = Some(2).map(|x| x % 2 == 0) != foo();
+    let _ = mac!(eq Some(2).map(|x| x % 2 == 0), Some(true));
+    let _ = mac!(some 2).map(|x| x % 2 == 0) == Some(true);
+    let _ = mac!(some_map 2) == Some(true);
+    let _ = mac!(map Some(2)) == Some(true);
 }
 
 #[rustfmt::skip]
@@ -41,6 +96,13 @@ fn result_methods() {
     });
     let _ = res.is_ok_and(|x| x > 1);
 
+    let _ = Ok::<usize, ()>(2).is_ok_and(|x| x % 2 == 0);
+    //~^ manual_is_variant_and
+    let _ = !Ok::<usize, ()>(2).is_ok_and(|x| x % 2 == 0);
+    //~^ manual_is_variant_and
+    let _ = !Ok::<usize, ()>(2).is_ok_and(|x| x % 2 == 0);
+    //~^ manual_is_variant_and
+
     // won't fix because the return type of the closure is not `bool`
     let _ = res.map(|x| x + 1).unwrap_or_default();
 
diff --git a/tests/ui/manual_is_variant_and.rs b/tests/ui/manual_is_variant_and.rs
@@ -4,6 +4,44 @@
 #[macro_use]
 extern crate option_helpers;
 
+struct Foo<T>(T);
+
+impl<T> Foo<T> {
+    fn map<F: FnMut(T) -> bool>(self, mut f: F) -> Option<bool> {
+        Some(f(self.0))
+    }
+}
+
+fn foo() -> Option<bool> {
+    Some(true)
+}
+
+macro_rules! some_true {
+    () => {
+        Some(true)
+    };
+}
+macro_rules! some_false {
+    () => {
+        Some(false)
+    };
+}
+
+macro_rules! mac {
+    (some $e:expr) => {
+        Some($e)
+    };
+    (some_map $e:expr) => {
+        Some($e).map(|x| x % 2 == 0)
+    };
+    (map $e:expr) => {
+        $e.map(|x| x % 2 == 0)
+    };
+    (eq $a:expr, $b:expr) => {
+        $a == $b
+    };
+}
+
 #[rustfmt::skip]
 fn option_methods() {
     let opt = Some(1);
@@ -27,13 +65,30 @@ fn option_methods() {
         //~^ manual_is_variant_and
         .unwrap_or_default();
 
+    let _ = Some(2).map(|x| x % 2 == 0) == Some(true);
+    //~^ manual_is_variant_and
+    let _ = Some(2).map(|x| x % 2 == 0) != Some(true);
+    //~^ manual_is_variant_and
+    let _ = Some(2).map(|x| x % 2 == 0) == some_true!();
+    //~^ manual_is_variant_and
+    let _ = Some(2).map(|x| x % 2 == 0) != some_false!();
+    //~^ manual_is_variant_and
+
     // won't fix because the return type of the closure is not `bool`
     let _ = opt.map(|x| x + 1).unwrap_or_default();
 
     let opt2 = Some('a');
     let _ = opt2.map(char::is_alphanumeric).unwrap_or_default(); // should lint
     //~^ manual_is_variant_and
     let _ = opt_map!(opt2, |x| x == 'a').unwrap_or_default(); // should not lint
+
+    // Should not lint.
+    let _ = Foo::<u32>(0).map(|x| x % 2 == 0) == Some(true);
+    let _ = Some(2).map(|x| x % 2 == 0) != foo();
+    let _ = mac!(eq Some(2).map(|x| x % 2 == 0), Some(true));
+    let _ = mac!(some 2).map(|x| x % 2 == 0) == Some(true);
+    let _ = mac!(some_map 2) == Some(true);
+    let _ = mac!(map Some(2)) == Some(true);
 }
 
 #[rustfmt::skip]
@@ -50,6 +105,13 @@ fn result_methods() {
     //~^ manual_is_variant_and
         .unwrap_or_default();
 
+    let _ = Ok::<usize, ()>(2).map(|x| x % 2 == 0) == Ok(true);
+    //~^ manual_is_variant_and
+    let _ = Ok::<usize, ()>(2).map(|x| x % 2 == 0) != Ok(true);
+    //~^ manual_is_variant_and
+    let _ = Ok::<usize, ()>(2).map(|x| x % 2 == 0) != Ok(true);
+    //~^ manual_is_variant_and
+
     // won't fix because the return type of the closure is not `bool`
     let _ = res.map(|x| x + 1).unwrap_or_default();
 
diff --git a/tests/ui/manual_is_variant_and.stderr b/tests/ui/manual_is_variant_and.stderr
@@ -1,5 +1,5 @@
 error: called `map(<f>).unwrap_or_default()` on an `Option` value
-  --> tests/ui/manual_is_variant_and.rs:13:17
+  --> tests/ui/manual_is_variant_and.rs:51:17
    |
 LL |       let _ = opt.map(|x| x > 1)
    |  _________________^
@@ -11,7 +11,7 @@ LL | |         .unwrap_or_default();
    = help: to override `-D warnings` add `#[allow(clippy::manual_is_variant_and)]`
 
 error: called `map(<f>).unwrap_or_default()` on an `Option` value
-  --> tests/ui/manual_is_variant_and.rs:18:17
+  --> tests/ui/manual_is_variant_and.rs:56:17
    |
 LL |       let _ = opt.map(|x| {
    |  _________________^
@@ -30,28 +30,52 @@ LL ~     });
    |
 
 error: called `map(<f>).unwrap_or_default()` on an `Option` value
-  --> tests/ui/manual_is_variant_and.rs:23:17
+  --> tests/ui/manual_is_variant_and.rs:61:17
    |
 LL |     let _ = opt.map(|x| x > 1).unwrap_or_default();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `is_some_and(|x| x > 1)`
 
 error: called `map(<f>).unwrap_or_default()` on an `Option` value
-  --> tests/ui/manual_is_variant_and.rs:26:10
+  --> tests/ui/manual_is_variant_and.rs:64:10
    |
 LL |           .map(|x| x > 1)
    |  __________^
 LL | |
 LL | |         .unwrap_or_default();
    | |____________________________^ help: use: `is_some_and(|x| x > 1)`
 
+error: called `.map() == Some()`
+  --> tests/ui/manual_is_variant_and.rs:68:13
+   |
+LL |     let _ = Some(2).map(|x| x % 2 == 0) == Some(true);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `Some(2).is_some_and(|x| x % 2 == 0)`
+
+error: called `.map() != Some()`
+  --> tests/ui/manual_is_variant_and.rs:70:13
+   |
+LL |     let _ = Some(2).map(|x| x % 2 == 0) != Some(true);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `Some(2).is_none_or(|x| x % 2 == 0)`
+
+error: called `.map() == Some()`
+  --> tests/ui/manual_is_variant_and.rs:72:13
+   |
+LL |     let _ = Some(2).map(|x| x % 2 == 0) == some_true!();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `Some(2).is_some_and(|x| x % 2 == 0)`
+
+error: called `.map() != Some()`
+  --> tests/ui/manual_is_variant_and.rs:74:13
+   |
+LL |     let _ = Some(2).map(|x| x % 2 == 0) != some_false!();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `Some(2).is_none_or(|x| x % 2 == 0)`
+
 error: called `map(<f>).unwrap_or_default()` on an `Option` value
-  --> tests/ui/manual_is_variant_and.rs:34:18
+  --> tests/ui/manual_is_variant_and.rs:81:18
    |
 LL |     let _ = opt2.map(char::is_alphanumeric).unwrap_or_default(); // should lint
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `is_some_and(char::is_alphanumeric)`
 
 error: called `map(<f>).unwrap_or_default()` on a `Result` value
-  --> tests/ui/manual_is_variant_and.rs:44:17
+  --> tests/ui/manual_is_variant_and.rs:99:17
    |
 LL |       let _ = res.map(|x| {
    |  _________________^
@@ -70,19 +94,37 @@ LL ~     });
    |
 
 error: called `map(<f>).unwrap_or_default()` on a `Result` value
-  --> tests/ui/manual_is_variant_and.rs:49:17
+  --> tests/ui/manual_is_variant_and.rs:104:17
    |
 LL |       let _ = res.map(|x| x > 1)
    |  _________________^
 LL | |
 LL | |         .unwrap_or_default();
    | |____________________________^ help: use: `is_ok_and(|x| x > 1)`
 
+error: called `.map() == Ok()`
+  --> tests/ui/manual_is_variant_and.rs:108:13
+   |
+LL |     let _ = Ok::<usize, ()>(2).map(|x| x % 2 == 0) == Ok(true);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `Ok::<usize, ()>(2).is_ok_and(|x| x % 2 == 0)`
+
+error: called `.map() != Ok()`
+  --> tests/ui/manual_is_variant_and.rs:110:13
+   |
+LL |     let _ = Ok::<usize, ()>(2).map(|x| x % 2 == 0) != Ok(true);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `!Ok::<usize, ()>(2).is_ok_and(|x| x % 2 == 0)`
+
+error: called `.map() != Ok()`
+  --> tests/ui/manual_is_variant_and.rs:112:13
+   |
+LL |     let _ = Ok::<usize, ()>(2).map(|x| x % 2 == 0) != Ok(true);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `!Ok::<usize, ()>(2).is_ok_and(|x| x % 2 == 0)`
+
 error: called `map(<f>).unwrap_or_default()` on a `Result` value
-  --> tests/ui/manual_is_variant_and.rs:57:18
+  --> tests/ui/manual_is_variant_and.rs:119:18
    |
 LL |     let _ = res2.map(char::is_alphanumeric).unwrap_or_default(); // should lint
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use: `is_ok_and(char::is_alphanumeric)`
 
-error: aborting due to 8 previous errors
+error: aborting due to 15 previous errors
 
