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Update error message

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Ryan Levick 2021-01-11 11:47:16 +01:00 • committed by Ryan Levick
parent 16c4afbde4
commit 95e330bd01
4 changed files with 30 additions and 15 deletions
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9
compiler/rustc_lint/src/noop_method_call.rs
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@ -39,7 +39,7 @@ declare_lint_pass!(NoopMethodCall => [NOOP_METHOD_CALL]);
impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
// We only care about method calls
if let ExprKind::MethodCall(..) = expr.kind {
if let ExprKind::MethodCall(call, ..) = expr.kind {
// Get the `DefId` only when dealing with an `AssocFn`
if let Some((DefKind::AssocFn, did)) =
cx.typeck_results().type_dependent_def(expr.hir_id)
@ -55,7 +55,7 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
}
let substs = cx.typeck_results().node_substs(expr.hir_id);
// We can't resolve on types that recursively require monomorphization,
// We can't resolve on types that require monomorphization,
// so check that we don't need to perfom substitution
if !substs.needs_subst() {
let param_env = cx.tcx.param_env(trait_id);
@ -73,9 +73,12 @@ impl<'tcx> LateLintPass<'tcx> for NoopMethodCall {
let expr_span = expr.span;
cx.struct_span_lint(NOOP_METHOD_CALL, expr_span, |lint| {
let message = "call to method that does nothing";
let method = &call.ident.name;
let message = format!("call to `.{}()` on a reference in this situation does nothing", &method);
lint.build(&message)
.span_label(expr_span, "unnecessary method call")
.note("the type the method is being called on and the return type are functionally equivalent.")
.note("therefore, the method call doesn't actually do anything and can be removed.")
.emit()
});
}