mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-19 09:33:36 +00:00
106 lines
4.3 KiB
Rust
106 lines
4.3 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::macros::{find_assert_args, root_macro_call_first_node, PanicExpn};
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use clippy_utils::path_res;
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use clippy_utils::source::snippet_with_context;
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use clippy_utils::ty::{implements_trait, is_copy, is_type_diagnostic_item};
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use clippy_utils::usage::local_used_after_expr;
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use rustc_errors::Applicability;
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use rustc_hir::def::Res;
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty::{self, Ty};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::sym;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for `assert!(r.is_ok())` or `assert!(r.is_err())` calls.
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///
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/// ### Why is this bad?
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/// An assertion failure cannot output an useful message of the error.
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///
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/// ### Known problems
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/// The suggested replacement decreases the readability of code and log output.
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///
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/// ### Example
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/// ```rust,ignore
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/// # let r = Ok::<_, ()>(());
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/// assert!(r.is_ok());
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/// # let r = Err::<_, ()>(());
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/// assert!(r.is_err());
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/// ```
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#[clippy::version = "1.64.0"]
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pub ASSERTIONS_ON_RESULT_STATES,
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restriction,
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"`assert!(r.is_ok())`/`assert!(r.is_err())` gives worse error message than directly calling `r.unwrap()`/`r.unwrap_err()`"
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}
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declare_lint_pass!(AssertionsOnResultStates => [ASSERTIONS_ON_RESULT_STATES]);
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impl<'tcx> LateLintPass<'tcx> for AssertionsOnResultStates {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
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if let Some(macro_call) = root_macro_call_first_node(cx, e)
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&& matches!(cx.tcx.get_diagnostic_name(macro_call.def_id), Some(sym::assert_macro))
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&& let Some((condition, panic_expn)) = find_assert_args(cx, e, macro_call.expn)
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&& matches!(panic_expn, PanicExpn::Empty)
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&& let ExprKind::MethodCall(method_segment, [recv], _) = condition.kind
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&& let result_type_with_refs = cx.typeck_results().expr_ty(recv)
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&& let result_type = result_type_with_refs.peel_refs()
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&& is_type_diagnostic_item(cx, result_type, sym::Result)
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&& let ty::Adt(_, substs) = result_type.kind()
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{
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if !is_copy(cx, result_type) {
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if result_type_with_refs != result_type {
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return;
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} else if let Res::Local(binding_id) = path_res(cx, recv)
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&& local_used_after_expr(cx, binding_id, recv)
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{
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return;
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}
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}
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let mut app = Applicability::MachineApplicable;
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match method_segment.ident.as_str() {
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"is_ok" if type_suitable_to_unwrap(cx, substs.type_at(1)) => {
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span_lint_and_sugg(
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cx,
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ASSERTIONS_ON_RESULT_STATES,
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macro_call.span,
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"called `assert!` with `Result::is_ok`",
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"replace with",
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format!(
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"{}.unwrap()",
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snippet_with_context(cx, recv.span, condition.span.ctxt(), "..", &mut app).0
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),
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app,
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);
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}
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"is_err" if type_suitable_to_unwrap(cx, substs.type_at(0)) => {
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span_lint_and_sugg(
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cx,
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ASSERTIONS_ON_RESULT_STATES,
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macro_call.span,
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"called `assert!` with `Result::is_err`",
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"replace with",
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format!(
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"{}.unwrap_err()",
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snippet_with_context(cx, recv.span, condition.span.ctxt(), "..", &mut app).0
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),
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app,
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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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}
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/// This checks whether a given type is known to implement Debug.
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fn has_debug_impl<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
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cx.tcx
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.get_diagnostic_item(sym::Debug)
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.map_or(false, |debug| implements_trait(cx, ty, debug, &[]))
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}
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fn type_suitable_to_unwrap<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
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has_debug_impl(cx, ty) && !ty.is_unit() && !ty.is_never()
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}
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