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Auto merge of #94584 - pnkfelix:inject-use-suggestion-sites, r=ekuber

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More robust fallback for `use` suggestion

Our old way to suggest where to add `use`s would first look for pre-existing `use`s in the relevant crate/module, and if there are *no* uses, it would fallback on trying to use another item as the basis for the suggestion.

But this was fragile, as illustrated in issue #87613

This PR instead identifies span of the first token after any inner attributes, and uses *that* as the fallback for the `use` suggestion.

Fix #87613
This commit is contained in:
bors 2022-03-15 03:56:33 +00:00
commit 95561b336c
27 changed files with 295 additions and 106 deletions
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113
compiler/rustc_resolve/src/lib.rs
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@ -71,7 +71,6 @@ use rustc_span::{Span, DUMMY_SP};
use smallvec::{smallvec, SmallVec};
use std::cell::{Cell, RefCell};
use std::collections::BTreeSet;
use std::ops::ControlFlow;
use std::{cmp, fmt, iter, mem, ptr};
use tracing::debug;
@ -315,74 +314,70 @@ impl<'a> From<&'a ast::PathSegment> for Segment {
}
}
#[derive(Debug)]
struct UsePlacementFinder {
target_module: NodeId,
span: Option<Span>,
found_use: bool,
first_legal_span: Option<Span>,
first_use_span: Option<Span>,
}
impl UsePlacementFinder {
fn check(krate: &Crate, target_module: NodeId) -> (Option<Span>, bool) {
let mut finder = UsePlacementFinder { target_module, span: None, found_use: false };
if let ControlFlow::Continue(..) = finder.check_mod(&krate.items, CRATE_NODE_ID) {
visit::walk_crate(&mut finder, krate);
let mut finder =
UsePlacementFinder { target_module, first_legal_span: None, first_use_span: None };
finder.visit_crate(krate);
if let Some(use_span) = finder.first_use_span {
(Some(use_span), true)
} else {
(finder.first_legal_span, false)
}
(finder.span, finder.found_use)
}
fn check_mod(&mut self, items: &[P<ast::Item>], node_id: NodeId) -> ControlFlow<()> {
if self.span.is_some() {
return ControlFlow::Break(());
}
if node_id != self.target_module {
return ControlFlow::Continue(());
}
// find a use statement
for item in items {
match item.kind {
ItemKind::Use(..) => {
// don't suggest placing a use before the prelude
// import or other generated ones
if !item.span.from_expansion() {
self.span = Some(item.span.shrink_to_lo());
self.found_use = true;
return ControlFlow::Break(());
}
}
// don't place use before extern crate
ItemKind::ExternCrate(_) => {}
// but place them before the first other item
_ => {
if self.span.map_or(true, |span| item.span < span)
&& !item.span.from_expansion()
{
self.span = Some(item.span.shrink_to_lo());
// don't insert between attributes and an item
// find the first attribute on the item
// FIXME: This is broken for active attributes.
for attr in &item.attrs {
if !attr.span.is_dummy()
&& self.span.map_or(true, |span| attr.span < span)
{
self.span = Some(attr.span.shrink_to_lo());
}
}
}
}
}
}
ControlFlow::Continue(())
}
}
impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
fn visit_item(&mut self, item: &'tcx ast::Item) {
if let ItemKind::Mod(_, ModKind::Loaded(items, ..)) = &item.kind {
if let ControlFlow::Break(..) = self.check_mod(items, item.id) {
return;
fn is_span_suitable_for_use_injection(s: Span) -> bool {
// don't suggest placing a use before the prelude
// import or other generated ones
!s.from_expansion()
}
fn search_for_any_use_in_items(items: &[P<ast::Item>]) -> Option<Span> {
for item in items {
if let ItemKind::Use(..) = item.kind {
if is_span_suitable_for_use_injection(item.span) {
return Some(item.span.shrink_to_lo());
}
}
visit::walk_item(self, item);
}
return None;
}
impl<'tcx> Visitor<'tcx> for UsePlacementFinder {
fn visit_crate(&mut self, c: &Crate) {
if self.target_module == CRATE_NODE_ID {
let inject = c.spans.inject_use_span;
if is_span_suitable_for_use_injection(inject) {
self.first_legal_span = Some(inject);
}
self.first_use_span = search_for_any_use_in_items(&c.items);
return;
} else {
visit::walk_crate(self, c);
}
}
fn visit_item(&mut self, item: &'tcx ast::Item) {
if self.target_module == item.id {
if let ItemKind::Mod(_, ModKind::Loaded(items, _inline, mod_spans)) = &item.kind {
let inject = mod_spans.inject_use_span;
if is_span_suitable_for_use_injection(inject) {
self.first_legal_span = Some(inject);
}
self.first_use_span = search_for_any_use_in_items(items);
return;
}
} else {
visit::walk_item(self, item);
}
}
}
@ -1282,7 +1277,7 @@ impl<'a> Resolver<'a> {
None,
ModuleKind::Def(DefKind::Mod, root_def_id, kw::Empty),
ExpnId::root(),
krate.span,
krate.spans.inner_span,
session.contains_name(&krate.attrs, sym::no_implicit_prelude),
&mut module_map,
);
@ -1295,7 +1290,7 @@ impl<'a> Resolver<'a> {
&mut FxHashMap::default(),
);
let definitions = Definitions::new(session.local_stable_crate_id(), krate.span);
let definitions = Definitions::new(session.local_stable_crate_id(), krate.spans.inner_span);
let root = definitions.get_root_def();
let mut visibilities = FxHashMap::default();