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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<'_>, scrutinee: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
// Type of expression is `bool`.
if *cx.typeck_results().expr_ty(scrutinee).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(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 mut app = Applicability::HasPlaceholders;
let ctxt = expr.span.ctxt();
let sugg = match (is_unit_expr(true_expr), is_unit_expr(false_expr)) {
(false, false) => Some(format!(
"if {} {} else {}",
snippet(cx, scrutinee.span, "b"),
expr_block(cx, true_expr, ctxt, "..", Some(expr.span), &mut app),
expr_block(cx, false_expr, ctxt, "..", Some(expr.span), &mut app)
)),
(false, true) => Some(format!(
"if {} {}",
snippet(cx, scrutinee.span, "b"),
expr_block(cx, true_expr, ctxt, "..", Some(expr.span), &mut app)
)),
(true, false) => {
let test = Sugg::hir(cx, scrutinee, "..");
Some(format!(
"if {} {}",
!test,
expr_block(cx, false_expr, ctxt, "..", Some(expr.span), &mut app)
))
},
(true, true) => None,
};
if let Some(sugg) = sugg {
diag.span_suggestion(
expr.span,
"consider using an `if`/`else` expression",
sugg,
Applicability::HasPlaceholders,
);
}
}
}
},
);
}
}
|
