let msg = if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
format!("unused import: `{}`", snippet)
} else {
- "unused import".to_string()
+ "unused import".to_owned()
};
self.tcx.lint_node(lint::builtin::UNUSED_IMPORTS, id, span, &msg);
}
!tcx.is_compiler_builtins(cnum)
&& !tcx.is_panic_runtime(cnum)
&& !tcx.has_global_allocator(cnum)
+ && !tcx.has_panic_handler(cnum)
})
.cloned()
.collect();
});
for extern_crate in &crates_to_lint {
- assert!(extern_crate.def_id.is_local());
+ let id = tcx.hir.as_local_node_id(extern_crate.def_id).unwrap();
+ let item = tcx.hir.expect_item(id);
// If the crate is fully unused, we suggest removing it altogether.
// We do this in any edition.
- if let Some(&span) = unused_extern_crates.get(&extern_crate.def_id) {
- assert_eq!(extern_crate.def_id.krate, LOCAL_CRATE);
- let hir_id = tcx.hir.definitions().def_index_to_hir_id(extern_crate.def_id.index);
- let id = tcx.hir.hir_to_node_id(hir_id);
- let msg = "unused extern crate";
- tcx.struct_span_lint_node(lint, id, span, msg)
- .span_suggestion_short_with_applicability(
- span,
- "remove it",
- String::new(),
- Applicability::MachineApplicable)
- .emit();
- continue;
+ if extern_crate.warn_if_unused {
+ if let Some(&span) = unused_extern_crates.get(&extern_crate.def_id) {
+ let msg = "unused extern crate";
+
+ // Removal suggestion span needs to include attributes (Issue #54400)
+ let span_with_attrs = tcx.get_attrs(extern_crate.def_id).iter()
+ .map(|attr| attr.span)
+ .fold(span, |acc, attr_span| acc.to(attr_span));
+
+ tcx.struct_span_lint_node(lint, id, span, msg)
+ .span_suggestion_short_with_applicability(
+ span_with_attrs,
+ "remove it",
+ String::new(),
+ Applicability::MachineApplicable)
+ .emit();
+ continue;
+ }
}
// If we are not in Rust 2018 edition, then we don't make any further
continue;
}
+ // If the extern crate isn't in the extern prelude,
+ // there is no way it can be written as an `use`.
+ let orig_name = extern_crate.orig_name.unwrap_or(item.name);
+ if !tcx.sess.extern_prelude.contains(&orig_name) {
+ continue;
+ }
+
// If the extern crate has any attributes, they may have funky
// semantics we can't faithfully represent using `use` (most
// notably `#[macro_use]`). Ignore it.
}
// Otherwise, we can convert it into a `use` of some kind.
- let hir_id = tcx.hir.definitions().def_index_to_hir_id(extern_crate.def_id.index);
- let id = tcx.hir.hir_to_node_id(hir_id);
- let item = tcx.hir.expect_item(id);
let msg = "`extern crate` is not idiomatic in the new edition";
let help = format!(
"convert it to a `{}`",
/// crate_name`), and -- perhaps surprisingly -- this stores the
/// *original* name (`item.name` will contain the new name)
orig_name: Option<ast::Name>,
+
+ /// if `false`, the original name started with `_`, so we shouldn't lint
+ /// about it going unused (but we should still emit idiom lints).
+ warn_if_unused: bool,
}
impl<'a, 'tcx, 'v> ItemLikeVisitor<'v> for CollectExternCrateVisitor<'a, 'tcx> {
def_id: extern_crate_def_id,
span: item.span,
orig_name,
+ warn_if_unused: !item.name.as_str().starts_with('_'),
}
);
}