fix incorrect suggestion for !(a >= b) as i32 == c

Author: CoCo-Japan-pan

clippy_lints/src/booleans.rs

@@ -176,13 +176,18 @@ fn check_inverted_bool_in_condition(
     );
 }
 
-fn check_simplify_not(cx: &LateContext<'_>, expr: &Expr<'_>) {
+fn check_simplify_not(cx: &LateContext<'_>, expr: &Expr<'_>, need_parens: bool) {
     if let ExprKind::Unary(UnOp::Not, inner) = &expr.kind
         && !expr.span.from_expansion()
         && !inner.span.from_expansion()
         && let Some(suggestion) = simplify_not(cx, inner)
         && cx.tcx.lint_level_at_node(NONMINIMAL_BOOL, expr.hir_id).0 != Level::Allow
     {
+        let suggestion = if need_parens {
+            format!("({})", suggestion)
+        } else {
+            suggestion
+        };
         span_lint_and_sugg(
             cx,
             NONMINIMAL_BOOL,
@@ -476,7 +481,7 @@ fn terminal_stats(b: &Bool) -> Stats {
 }
 
 impl<'a, 'tcx> NonminimalBoolVisitor<'a, 'tcx> {
-    fn bool_expr(&self, e: &'tcx Expr<'_>) {
+    fn bool_expr(&self, e: &'tcx Expr<'_>, need_parens: bool) {
         let mut h2q = Hir2Qmm {
             terminals: Vec::new(),
             cx: self.cx,
@@ -569,7 +574,7 @@ impl<'a, 'tcx> NonminimalBoolVisitor<'a, 'tcx> {
                 }
             };
             if improvements.is_empty() {
-                check_simplify_not(self.cx, e);
+                check_simplify_not(self.cx, e, need_parens);
             } else {
                 nonminimal_bool_lint(
                     improvements
@@ -586,8 +591,15 @@ impl<'a, 'tcx> Visitor<'tcx> for NonminimalBoolVisitor<'a, 'tcx> {
     fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
         if !e.span.from_expansion() {
             match &e.kind {
+                ExprKind::Cast(inner, _) => {
+                    if self.cx.typeck_results().expr_ty(inner).is_bool() {
+                        // we are casting bool into some type, so we may need a parenthesis (#12761)
+                        self.bool_expr(inner, true);
+                        return;
+                    }
+                },
                 ExprKind::Binary(binop, _, _) if binop.node == BinOpKind::Or || binop.node == BinOpKind::And => {
-                    self.bool_expr(e);
+                    self.bool_expr(e, false);
                 },
                 ExprKind::Unary(UnOp::Not, inner) => {
                     if let ExprKind::Unary(UnOp::Not, ex) = inner.kind
@@ -596,7 +608,7 @@ impl<'a, 'tcx> Visitor<'tcx> for NonminimalBoolVisitor<'a, 'tcx> {
                         return;
                     }
                     if self.cx.typeck_results().node_types()[inner.hir_id].is_bool() {
-                        self.bool_expr(e);
+                        self.bool_expr(e, false);
                     }
                 },
                 _ => {},

tests/ui/nonminimal_bool_methods.fixed

@@ -115,4 +115,11 @@ fn issue_12625() {
     if a as u64 > b {} //~ ERROR: this boolean expression can be simplified
 }
 
+fn issue_12761() {
+    let a = 0;
+    let b = 0;
+    let c = 0;
+    if (a < b) as i32 == c {} //~ ERROR: this boolean expression can be simplified
+}
+
 fn main() {}

tests/ui/nonminimal_bool_methods.rs

@@ -115,4 +115,11 @@ fn issue_12625() {
     if !(a as u64 <= b) {} //~ ERROR: this boolean expression can be simplified
 }
 
+fn issue_12761() {
+    let a = 0;
+    let b = 0;
+    let c = 0;
+    if !(a >= b) as i32 == c {} //~ ERROR: this boolean expression can be simplified
+}
+
 fn main() {}

tests/ui/nonminimal_bool_methods.stderr

@@ -97,5 +97,11 @@ error: this boolean expression can be simplified
 LL |     if !(a as u64 <= b) {}
    |        ^^^^^^^^^^^^^^^^ help: try: `a as u64 > b`
 
-error: aborting due to 16 previous errors
+error: this boolean expression can be simplified
+  --> tests/ui/nonminimal_bool_methods.rs:122:8
+   |
+LL |     if !(a >= b) as i32 == c {}
+   |        ^^^^^^^^^ help: try: `(a < b)`
+
+error: aborting due to 17 previous errors