-use super::utils::{get_arg_name, match_var, remove_blocks, snippet, span_lint_and_sugg};
+use super::utils::{get_arg_name, match_var, remove_blocks, snippet_with_applicability, span_lint_and_sugg};
+use if_chain::if_chain;
use rustc::hir::*;
-use rustc::lint::*;
+use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use rustc::{declare_lint_pass, declare_tool_lint};
+use rustc_errors::Applicability;
-/// **What it does:** Checks for matches being used to destructure a single-variant enum
-/// or tuple struct where a `let` will suffice.
-///
-/// **Why is this bad?** Just readability – `let` doesn't nest, whereas a `match` does.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// enum Wrapper {
-/// Data(i32),
-/// }
-///
-/// let wrapper = Wrapper::Data(42);
-///
-/// let data = match wrapper {
-/// Wrapper::Data(i) => i,
-/// };
-/// ```
-///
-/// The correct use would be:
-/// ```rust
-/// enum Wrapper {
-/// Data(i32),
-/// }
-///
-/// let wrapper = Wrapper::Data(42);
-/// let Wrapper::Data(data) = wrapper;
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for matches being used to destructure a single-variant enum
+ /// or tuple struct where a `let` will suffice.
+ ///
+ /// **Why is this bad?** Just readability – `let` doesn't nest, whereas a `match` does.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// enum Wrapper {
+ /// Data(i32),
+ /// }
+ ///
+ /// let wrapper = Wrapper::Data(42);
+ ///
+ /// let data = match wrapper {
+ /// Wrapper::Data(i) => i,
+ /// };
+ /// ```
+ ///
+ /// The correct use would be:
+ /// ```rust
+ /// enum Wrapper {
+ /// Data(i32),
+ /// }
+ ///
+ /// let wrapper = Wrapper::Data(42);
+ /// let Wrapper::Data(data) = wrapper;
+ /// ```
pub INFALLIBLE_DESTRUCTURING_MATCH,
style,
"a match statement with a single infallible arm instead of a `let`"
}
-#[derive(Copy, Clone, Default)]
-pub struct Pass;
+declare_lint_pass!(InfallibleDestructingMatch => [INFALLIBLE_DESTRUCTURING_MATCH]);
-impl LintPass for Pass {
- fn get_lints(&self) -> LintArray {
- lint_array!(INFALLIBLE_DESTRUCTURING_MATCH)
- }
-}
-
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InfallibleDestructingMatch {
fn check_local(&mut self, cx: &LateContext<'a, 'tcx>, local: &'tcx Local) {
if_chain! {
if let Some(ref expr) = local.init;
- if let Expr_::ExprMatch(ref target, ref arms, MatchSource::Normal) = expr.node;
+ if let ExprKind::Match(ref target, ref arms, MatchSource::Normal) = expr.node;
if arms.len() == 1 && arms[0].pats.len() == 1 && arms[0].guard.is_none();
if let PatKind::TupleStruct(QPath::Resolved(None, ref variant_name), ref args, _) = arms[0].pats[0].node;
if args.len() == 1;
if match_var(body, arg);
then {
+ let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
INFALLIBLE_DESTRUCTURING_MATCH,
"try this",
format!(
"let {}({}) = {};",
- snippet(cx, variant_name.span, ".."),
- snippet(cx, local.pat.span, ".."),
- snippet(cx, target.span, ".."),
+ snippet_with_applicability(cx, variant_name.span, "..", &mut applicability),
+ snippet_with_applicability(cx, local.pat.span, "..", &mut applicability),
+ snippet_with_applicability(cx, target.span, "..", &mut applicability),
),
+ applicability,
);
}
}