fix: unchecked_time_subtraction FN on Ops::sub method call

Author: profetia

clippy_lints/src/time_subtraction.rs

@@ -84,43 +84,57 @@ impl_lint_pass!(UncheckedTimeSubtraction => [MANUAL_INSTANT_ELAPSED, UNCHECKED_T
 
 impl LateLintPass<'_> for UncheckedTimeSubtraction {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'_ Expr<'_>) {
-        if let ExprKind::Binary(
-            Spanned {
-                node: BinOpKind::Sub, ..
+        match expr.kind {
+            ExprKind::Binary(
+                Spanned {
+                    node: BinOpKind::Sub, ..
+                },
+                lhs,
+                rhs,
+            ) => {
+                self.check_unchecked_time_subtraction(cx, expr, lhs, rhs);
             },
-            lhs,
-            rhs,
-        ) = expr.kind
-        {
-            let typeck = cx.typeck_results();
-            let lhs_ty = typeck.expr_ty(lhs);
-            let rhs_ty = typeck.expr_ty(rhs);
+            ExprKind::MethodCall(fn_name, lhs, [rhs], _)
+                if let Some(fn_impl_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
+                    && let Some(sym::sub) = cx.tcx.get_diagnostic_name(fn_impl_id) =>
+            {
+                self.check_unchecked_time_subtraction(cx, expr, lhs, rhs);
+            },
+            _ => {},
+        }
+    }
+}
 
-            if lhs_ty.is_diag_item(cx, sym::Instant) {
-                // Instant::now() - instant
-                if is_instant_now_call(cx, lhs)
-                    && rhs_ty.is_diag_item(cx, sym::Instant)
-                    && let Some(sugg) = Sugg::hir_opt(cx, rhs)
-                {
-                    print_manual_instant_elapsed_sugg(cx, expr, sugg);
-                }
-                // instant - duration
-                else if rhs_ty.is_diag_item(cx, sym::Duration)
-                    && !expr.span.from_expansion()
-                    && self.msrv.meets(cx, msrvs::TRY_FROM)
-                {
-                    print_unchecked_duration_subtraction_sugg(cx, lhs, rhs, expr);
-                }
+impl UncheckedTimeSubtraction {
+    fn check_unchecked_time_subtraction(&self, cx: &LateContext<'_>, expr: &Expr<'_>, lhs: &Expr<'_>, rhs: &Expr<'_>) {
+        let typeck = cx.typeck_results();
+        let lhs_ty = typeck.expr_ty(lhs);
+        let rhs_ty = typeck.expr_ty(rhs);
+
+        if lhs_ty.is_diag_item(cx, sym::Instant) {
+            // Instant::now() - instant
+            if is_instant_now_call(cx, lhs)
+                && rhs_ty.is_diag_item(cx, sym::Instant)
+                && let Some(sugg) = Sugg::hir_opt(cx, rhs)
+            {
+                print_manual_instant_elapsed_sugg(cx, expr, sugg);
             }
-            // duration - duration
-            else if lhs_ty.is_diag_item(cx, sym::Duration)
-                && rhs_ty.is_diag_item(cx, sym::Duration)
+            // instant - duration
+            else if rhs_ty.is_diag_item(cx, sym::Duration)
                 && !expr.span.from_expansion()
                 && self.msrv.meets(cx, msrvs::TRY_FROM)
             {
                 print_unchecked_duration_subtraction_sugg(cx, lhs, rhs, expr);
             }
         }
+        // duration - duration
+        else if lhs_ty.is_diag_item(cx, sym::Duration)
+            && rhs_ty.is_diag_item(cx, sym::Duration)
+            && !expr.span.from_expansion()
+            && self.msrv.meets(cx, msrvs::TRY_FROM)
+        {
+            print_unchecked_duration_subtraction_sugg(cx, lhs, rhs, expr);
+        }
     }
 }
 

tests/ui/unchecked_time_subtraction.fixed

@@ -35,3 +35,14 @@ fn main() {
     let _ = (2 * dur1).checked_sub(dur2).unwrap();
     //~^ unchecked_time_subtraction
 }
+
+fn issue16230() {
+    use std::ops::Sub as _;
+    use std::time::Duration;
+
+    Duration::ZERO.checked_sub(Duration::MAX).unwrap();
+    //~^ unchecked_time_subtraction
+
+    let _ = Duration::ZERO.checked_sub(Duration::MAX).unwrap();
+    //~^ unchecked_time_subtraction
+}

tests/ui/unchecked_time_subtraction.rs

@@ -35,3 +35,14 @@ fn main() {
     let _ = 2 * dur1 - dur2;
     //~^ unchecked_time_subtraction
 }
+
+fn issue16230() {
+    use std::ops::Sub as _;
+    use std::time::Duration;
+
+    Duration::ZERO.sub(Duration::MAX);
+    //~^ unchecked_time_subtraction
+
+    let _ = Duration::ZERO - Duration::MAX;
+    //~^ unchecked_time_subtraction
+}

tests/ui/unchecked_time_subtraction.stderr

@@ -49,5 +49,17 @@ error: unchecked subtraction of a `Duration`
 LL |     let _ = 2 * dur1 - dur2;
    |             ^^^^^^^^^^^^^^^ help: try: `(2 * dur1).checked_sub(dur2).unwrap()`
 
-error: aborting due to 8 previous errors
+error: unchecked subtraction of a `Duration`
+  --> tests/ui/unchecked_time_subtraction.rs:43:5
+   |
+LL |     Duration::ZERO.sub(Duration::MAX);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Duration::ZERO.checked_sub(Duration::MAX).unwrap()`
+
+error: unchecked subtraction of a `Duration`
+  --> tests/ui/unchecked_time_subtraction.rs:46:13
+   |
+LL |     let _ = Duration::ZERO - Duration::MAX;
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `Duration::ZERO.checked_sub(Duration::MAX).unwrap()`
+
+error: aborting due to 10 previous errors