rust/clippy_lints/src/assertions_on_constants.rs

85 lines
2.9 KiB
Rust

use clippy_utils::consts::{constant_with_source, Constant, ConstantSource};
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::macros::{find_assert_args, root_macro_call_first_node, PanicExpn};
use rustc_hir::{Expr, Item, ItemKind, Node};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::declare_lint_pass;
use rustc_span::sym;
declare_clippy_lint! {
/// ### What it does
/// Checks for `assert!(true)` and `assert!(false)` calls.
///
/// ### Why is this bad?
/// Will be optimized out by the compiler or should probably be replaced by a
/// `panic!()` or `unreachable!()`
///
/// ### Example
/// ```rust,ignore
/// assert!(false)
/// assert!(true)
/// const B: bool = false;
/// assert!(B)
/// ```
#[clippy::version = "1.34.0"]
pub ASSERTIONS_ON_CONSTANTS,
style,
"`assert!(true)` / `assert!(false)` will be optimized out by the compiler, and should probably be replaced by a `panic!()` or `unreachable!()`"
}
declare_lint_pass!(AssertionsOnConstants => [ASSERTIONS_ON_CONSTANTS]);
impl<'tcx> LateLintPass<'tcx> for AssertionsOnConstants {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
let Some(macro_call) = root_macro_call_first_node(cx, e) else {
return;
};
let is_debug = match cx.tcx.get_diagnostic_name(macro_call.def_id) {
Some(sym::debug_assert_macro) => true,
Some(sym::assert_macro) => false,
_ => return,
};
let Some((condition, panic_expn)) = find_assert_args(cx, e, macro_call.expn) else {
return;
};
let Some((Constant::Bool(val), source)) = constant_with_source(cx, cx.typeck_results(), condition) else {
return;
};
if let ConstantSource::Constant = source
&& let Some(node) = cx.tcx.hir().find_parent(e.hir_id)
&& let Node::Item(Item {
kind: ItemKind::Const(..),
..
}) = node
{
return;
}
if val {
span_lint_and_help(
cx,
ASSERTIONS_ON_CONSTANTS,
macro_call.span,
&format!(
"`{}!(true)` will be optimized out by the compiler",
cx.tcx.item_name(macro_call.def_id)
),
None,
"remove it",
);
} else if !is_debug {
let (assert_arg, panic_arg) = match panic_expn {
PanicExpn::Empty => ("", ""),
_ => (", ..", ".."),
};
span_lint_and_help(
cx,
ASSERTIONS_ON_CONSTANTS,
macro_call.span,
&format!("`assert!(false{assert_arg})` should probably be replaced"),
None,
&format!("use `panic!({panic_arg})` or `unreachable!({panic_arg})`"),
);
}
}
}