110 lines
3.5 KiB
Rust
110 lines
3.5 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_then;
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use clippy_utils::sugg::Sugg;
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use clippy_utils::{in_constant, is_else_clause};
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use rustc_ast::LitKind;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::declare_lint_pass;
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declare_clippy_lint! {
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/// ### What it does
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/// Instead of using an if statement to convert a bool to an int,
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/// this lint suggests using a `from()` function or an `as` coercion.
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///
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/// ### Why is this bad?
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/// Coercion or `from()` is another way to convert bool to a number.
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/// Both methods are guaranteed to return 1 for true, and 0 for false.
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///
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/// See https://doc.rust-lang.org/std/primitive.bool.html#impl-From%3Cbool%3E
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///
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/// ### Example
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/// ```no_run
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/// # let condition = false;
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/// if condition {
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/// 1_i64
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/// } else {
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/// 0
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/// };
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/// ```
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/// Use instead:
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/// ```no_run
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/// # let condition = false;
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/// i64::from(condition);
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/// ```
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/// or
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/// ```no_run
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/// # let condition = false;
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/// condition as i64;
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/// ```
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#[clippy::version = "1.65.0"]
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pub BOOL_TO_INT_WITH_IF,
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pedantic,
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"using if to convert bool to int"
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}
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declare_lint_pass!(BoolToIntWithIf => [BOOL_TO_INT_WITH_IF]);
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impl<'tcx> LateLintPass<'tcx> for BoolToIntWithIf {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
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if let ExprKind::If(cond, then, Some(else_)) = expr.kind
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&& matches!(cond.kind, ExprKind::DropTemps(_))
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&& let Some(then_lit) = as_int_bool_lit(then)
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&& let Some(else_lit) = as_int_bool_lit(else_)
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&& then_lit != else_lit
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&& !expr.span.from_expansion()
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&& !in_constant(cx, expr.hir_id)
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{
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let ty = cx.typeck_results().expr_ty(then);
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let mut applicability = Applicability::MachineApplicable;
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let snippet = {
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let mut sugg = Sugg::hir_with_applicability(cx, cond, "..", &mut applicability);
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if !then_lit {
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sugg = !sugg;
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}
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sugg
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};
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let suggestion = {
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let mut s = Sugg::NonParen(format!("{ty}::from({snippet})").into());
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// when used in else clause if statement should be wrapped in curly braces
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if is_else_clause(cx.tcx, expr) {
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s = s.blockify();
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}
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s
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};
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let into_snippet = snippet.clone().maybe_par();
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let as_snippet = snippet.as_ty(ty);
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span_lint_and_then(
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cx,
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BOOL_TO_INT_WITH_IF,
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expr.span,
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"boolean to int conversion using if",
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|diag| {
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diag.span_suggestion(expr.span, "replace with from", suggestion, applicability);
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diag.note(format!(
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"`{as_snippet}` or `{into_snippet}.into()` can also be valid options"
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));
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},
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);
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}
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}
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}
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fn as_int_bool_lit(e: &Expr<'_>) -> Option<bool> {
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if let ExprKind::Block(b, _) = e.kind
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&& b.stmts.is_empty()
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&& let Some(e) = b.expr
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&& let ExprKind::Lit(lit) = e.kind
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&& let LitKind::Int(x, _) = lit.node
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{
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match x.get() {
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0 => Some(false),
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1 => Some(true),
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_ => None,
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}
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} else {
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None
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}
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}
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