manual_rem_euclid: Check HIR tree first.

Author: Jarcho

clippy_lints/src/manual_rem_euclid.rs

@@ -48,35 +48,30 @@ impl_lint_pass!(ManualRemEuclid => [MANUAL_REM_EUCLID]);
 
 impl<'tcx> LateLintPass<'tcx> for ManualRemEuclid {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
-        if !self.msrv.meets(msrvs::REM_EUCLID) {
-            return;
-        }
-
-        if in_constant(cx, expr.hir_id) && !self.msrv.meets(msrvs::REM_EUCLID_CONST) {
-            return;
-        }
-
-        if in_external_macro(cx.sess(), expr.span) {
-            return;
-        }
-
         // (x % c + c) % c
-        if let ExprKind::Binary(op1, expr1, right) = expr.kind
-            && op1.node == BinOpKind::Rem
+        if let ExprKind::Binary(rem_op, rem_lhs, rem_rhs) = expr.kind
+            && rem_op.node == BinOpKind::Rem
+            && let ExprKind::Binary(add_op, add_lhs, add_rhs) = rem_lhs.kind
+            && add_op.node == BinOpKind::Add
             && let ctxt = expr.span.ctxt()
-            && expr1.span.ctxt() == ctxt
-            && let Some(const1) = check_for_unsigned_int_constant(cx, right)
-            && let ExprKind::Binary(op2, left, right) = expr1.kind
-            && op2.node == BinOpKind::Add
-            && let Some((const2, expr2)) = check_for_either_unsigned_int_constant(cx, left, right)
-            && expr2.span.ctxt() == ctxt
-            && let ExprKind::Binary(op3, expr3, right) = expr2.kind
-            && op3.node == BinOpKind::Rem
-            && let Some(const3) = check_for_unsigned_int_constant(cx, right)
+            && rem_lhs.span.ctxt() == ctxt
+            && rem_rhs.span.ctxt() == ctxt
+            && add_lhs.span.ctxt() == ctxt
+            && add_rhs.span.ctxt() == ctxt
+            && !in_external_macro(cx.sess(), expr.span)
+            && self.msrv.meets(msrvs::REM_EUCLID)
+            && (self.msrv.meets(msrvs::REM_EUCLID_CONST) || !in_constant(cx, expr.hir_id))
+            && let Some(const1) = check_for_unsigned_int_constant(cx, rem_rhs)
+            && let Some((const2, add_other)) = check_for_either_unsigned_int_constant(cx, add_lhs, add_rhs)
+            && let ExprKind::Binary(rem2_op, rem2_lhs, rem2_rhs) = add_other.kind
+            && rem2_op.node == BinOpKind::Rem
+            && const1 == const2
+            && let Some(hir_id) = path_to_local(rem2_lhs)
+            && let Some(const3) = check_for_unsigned_int_constant(cx, rem2_rhs)
             // Also ensures the const is nonzero since zero can't be a divisor
-            && const1 == const2 && const2 == const3
-            && let Some(hir_id) = path_to_local(expr3)
-            && let Node::Pat(_) = cx.tcx.hir_node(hir_id)
+            && const2 == const3
+            && rem2_lhs.span.ctxt() == ctxt
+            && rem2_rhs.span.ctxt() == ctxt
         {
             // Apply only to params or locals with annotated types
             match cx.tcx.parent_hir_node(hir_id) {
@@ -91,7 +86,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualRemEuclid {
             };
 
             let mut app = Applicability::MachineApplicable;
-            let rem_of = snippet_with_context(cx, expr3.span, ctxt, "_", &mut app).0;
+            let rem_of = snippet_with_context(cx, rem2_lhs.span, ctxt, "_", &mut app).0;
             span_lint_and_sugg(
                 cx,
                 MANUAL_REM_EUCLID,