122 lines
3.9 KiB
Rust
122 lines
3.9 KiB
Rust
use rustc_ast::LitKind;
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use rustc_hir::{Block, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use clippy_utils::{diagnostics::span_lint_and_then, is_else_clause, is_integer_literal, sugg::Sugg};
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use rustc_errors::Applicability;
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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 idiomatic 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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/// ```rust
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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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/// ```rust
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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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/// ```rust
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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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style,
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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, ctx: &LateContext<'tcx>, expr: &'tcx rustc_hir::Expr<'tcx>) {
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if !expr.span.from_expansion() {
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check_if_else(ctx, expr);
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}
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}
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}
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fn check_if_else<'tcx>(ctx: &LateContext<'tcx>, expr: &'tcx rustc_hir::Expr<'tcx>) {
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if let ExprKind::If(check, then, Some(else_)) = expr.kind
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&& let Some(then_lit) = int_literal(then)
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&& let Some(else_lit) = int_literal(else_)
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{
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let inverted = if is_integer_literal(then_lit, 1) && is_integer_literal(else_lit, 0) {
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false
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} else if is_integer_literal(then_lit, 0) && is_integer_literal(else_lit, 1) {
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true
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} else {
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// Expression isn't boolean, exit
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return;
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};
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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(ctx, check, "..", &mut applicability);
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if inverted {
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sugg = !sugg;
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}
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sugg
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};
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let ty = ctx.typeck_results().expr_ty(then_lit); // then and else must be of same type
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let suggestion = {
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let wrap_in_curly = is_else_clause(ctx.tcx, expr);
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let mut s = Sugg::NonParen(format!("{ty}::from({snippet})").into());
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if wrap_in_curly {
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s = s.blockify();
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}
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s
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}; // when used in else clause if statement should be wrapped in curly braces
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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(ctx,
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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(
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expr.span,
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"replace with from",
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suggestion,
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applicability,
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);
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diag.note(format!("`{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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// If block contains only a int literal expression, return literal expression
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fn int_literal<'tcx>(expr: &'tcx rustc_hir::Expr<'tcx>) -> Option<&'tcx rustc_hir::Expr<'tcx>> {
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if let ExprKind::Block(block, _) = expr.kind
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&& let Block {
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stmts: [], // Shouldn't lint if statements with side effects
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expr: Some(expr),
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..
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} = block
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&& let ExprKind::Lit(lit) = &expr.kind
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&& let LitKind::Int(_, _) = lit.node
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{
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Some(expr)
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} else {
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None
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}
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}
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