+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::is_unit_expr;
+use clippy_utils::source::{expr_block, snippet};
+use clippy_utils::sugg::Sugg;
+use rustc_ast::LitKind;
+use rustc_errors::Applicability;
+use rustc_hir::{Arm, Expr, ExprKind, PatKind};
+use rustc_lint::LateContext;
+use rustc_middle::ty;
+
+use super::MATCH_BOOL;
+
+pub(crate) fn check(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
+ // Type of expression is `bool`.
+ if *cx.typeck_results().expr_ty(ex).kind() == ty::Bool {
+ span_lint_and_then(
+ cx,
+ MATCH_BOOL,
+ expr.span,
+ "you seem to be trying to match on a boolean expression",
+ move |diag| {
+ if arms.len() == 2 {
+ // no guards
+ let exprs = if let PatKind::Lit(arm_bool) = arms[0].pat.kind {
+ if let ExprKind::Lit(ref lit) = arm_bool.kind {
+ match lit.node {
+ LitKind::Bool(true) => Some((&*arms[0].body, &*arms[1].body)),
+ LitKind::Bool(false) => Some((&*arms[1].body, &*arms[0].body)),
+ _ => None,
+ }
+ } else {
+ None
+ }
+ } else {
+ None
+ };
+
+ if let Some((true_expr, false_expr)) = exprs {
+ let sugg = match (is_unit_expr(true_expr), is_unit_expr(false_expr)) {
+ (false, false) => Some(format!(
+ "if {} {} else {}",
+ snippet(cx, ex.span, "b"),
+ expr_block(cx, true_expr, None, "..", Some(expr.span)),
+ expr_block(cx, false_expr, None, "..", Some(expr.span))
+ )),
+ (false, true) => Some(format!(
+ "if {} {}",
+ snippet(cx, ex.span, "b"),
+ expr_block(cx, true_expr, None, "..", Some(expr.span))
+ )),
+ (true, false) => {
+ let test = Sugg::hir(cx, ex, "..");
+ Some(format!(
+ "if {} {}",
+ !test,
+ expr_block(cx, false_expr, None, "..", Some(expr.span))
+ ))
+ },
+ (true, true) => None,
+ };
+
+ if let Some(sugg) = sugg {
+ diag.span_suggestion(
+ expr.span,
+ "consider using an `if`/`else` expression",
+ sugg,
+ Applicability::HasPlaceholders,
+ );
+ }
+ }
+ }
+ },
+ );
+ }
+}