73 lines
2.4 KiB
Rust
73 lines
2.4 KiB
Rust
use if_chain::if_chain;
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use rustc_hir::{Impl, ImplItem, ImplItemKind, ItemKind};
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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 crate::utils::span_lint_and_help;
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use crate::utils::visitors::LocalUsedVisitor;
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declare_clippy_lint! {
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/// **What it does:** Checks methods that contain a `self` argument but don't use it
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///
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/// **Why is this bad?** It may be clearer to define the method as an associated function instead
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/// of an instance method if it doesn't require `self`.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust,ignore
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/// struct A;
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/// impl A {
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/// fn method(&self) {}
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/// }
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/// ```
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///
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/// Could be written:
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///
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/// ```rust,ignore
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/// struct A;
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/// impl A {
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/// fn method() {}
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/// }
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/// ```
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pub UNUSED_SELF,
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pedantic,
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"methods that contain a `self` argument but don't use it"
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}
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declare_lint_pass!(UnusedSelf => [UNUSED_SELF]);
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impl<'tcx> LateLintPass<'tcx> for UnusedSelf {
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fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &ImplItem<'_>) {
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if impl_item.span.from_expansion() {
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return;
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}
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let parent = cx.tcx.hir().get_parent_item(impl_item.hir_id);
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let parent_item = cx.tcx.hir().expect_item(parent);
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let def_id = cx.tcx.hir().local_def_id(impl_item.hir_id);
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let assoc_item = cx.tcx.associated_item(def_id);
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if_chain! {
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if let ItemKind::Impl(Impl { of_trait: None, .. }) = parent_item.kind;
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if assoc_item.fn_has_self_parameter;
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if let ImplItemKind::Fn(.., body_id) = &impl_item.kind;
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let body = cx.tcx.hir().body(*body_id);
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if !body.params.is_empty();
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then {
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let self_param = &body.params[0];
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let self_hir_id = self_param.pat.hir_id;
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if !LocalUsedVisitor::new(cx, self_hir_id).check_body(body) {
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span_lint_and_help(
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cx,
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UNUSED_SELF,
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self_param.span,
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"unused `self` argument",
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None,
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"consider refactoring to a associated function",
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);
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return;
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}
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}
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}
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}
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}
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