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Rollup merge of #87614 - notriddle:notriddle-count2len, r=Mark-Simulacrum

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Recommend fix `count()` -> `len()` on slices

Fixes #87302
This commit is contained in:
Matthias Krüger 2021-12-07 11:04:56 +01:00 • committed by GitHub
commit f84a734a8e
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4 changed files with 68 additions and 3 deletions
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26
compiler/rustc_typeck/src/check/method/suggest.rs
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@ -67,6 +67,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
}
fn is_slice_ty(&self, ty: Ty<'tcx>, span: Span) -> bool {
self.autoderef(span, ty).any(|(ty, _)| matches!(ty.kind(), ty::Slice(..) | ty::Array(..)))
}
pub fn report_method_error(
&self,
mut span: Span,
@ -691,7 +695,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let mut restrict_type_params = false;
let mut unsatisfied_bounds = false;
if !unsatisfied_predicates.is_empty() {
if item_name.name == sym::count && self.is_slice_ty(actual, span) {
let msg = "consider using `len` instead";
if let SelfSource::MethodCall(_expr) = source {
err.span_suggestion_short(
span,
msg,
String::from("len"),
Applicability::MachineApplicable,
);
} else {
err.span_label(span, msg);
}
if let Some(iterator_trait) = self.tcx.get_diagnostic_item(sym::Iterator) {
let iterator_trait = self.tcx.def_path_str(iterator_trait);
err.note(&format!("`count` is defined on `{iterator_trait}`, which `{actual}` does not implement"));
}
} else if !unsatisfied_predicates.is_empty() {
let def_span = |def_id| {
self.tcx.sess.source_map().guess_head_span(self.tcx.def_span(def_id))
};
@ -990,9 +1010,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
}
let mut fallback_span = true;
let msg = "remove this method call";
if item_name.name == sym::as_str && actual.peel_refs().is_str() {
let msg = "remove this method call";
let mut fallback_span = true;
if let SelfSource::MethodCall(expr) = source {
let call_expr =
self.tcx.hir().expect_expr(self.tcx.hir().get_parent_node(expr.hir_id));