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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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18
compiler/rustc_ast/src/ast.rs
View file

@ -510,7 +510,7 @@ pub struct WhereEqPredicate {
pub struct Crate {
pub attrs: Vec<Attribute>,
pub items: Vec<P<Item>>,
pub span: Span,
pub spans: ModSpans,
/// Must be equal to `CRATE_NODE_ID` after the crate root is expanded, but may hold
/// expansion placeholders or an unassigned value (`DUMMY_NODE_ID`) before that.
pub id: NodeId,
@ -2317,11 +2317,25 @@ pub enum ModKind {
/// or with definition outlined to a separate file `mod foo;` and already loaded from it.
/// The inner span is from the first token past `{` to the last token until `}`,
/// or from the first to the last token in the loaded file.
Loaded(Vec<P<Item>>, Inline, Span),
Loaded(Vec<P<Item>>, Inline, ModSpans),
/// Module with definition outlined to a separate file `mod foo;` but not yet loaded from it.
Unloaded,
}
#[derive(Copy, Clone, Encodable, Decodable, Debug)]
pub struct ModSpans {
/// `inner_span` covers the body of the module; for a file module, its the whole file.
/// For an inline module, its the span inside the `{ ... }`, not including the curly braces.
pub inner_span: Span,
pub inject_use_span: Span,
}
impl Default for ModSpans {
fn default() -> ModSpans {
ModSpans { inner_span: Default::default(), inject_use_span: Default::default() }
}
}
/// Foreign module declaration.
///
/// E.g., `extern { .. }` or `extern "C" { .. }`.

11
compiler/rustc_ast/src/mut_visit.rs
View file

@ -1009,8 +1009,9 @@ pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
ItemKind::Mod(unsafety, mod_kind) => {
visit_unsafety(unsafety, vis);
match mod_kind {
ModKind::Loaded(items, _inline, inner_span) => {
ModKind::Loaded(items, _inline, ModSpans { inner_span, inject_use_span }) => {
vis.visit_span(inner_span);
vis.visit_span(inject_use_span);
items.flat_map_in_place(|item| vis.flat_map_item(item));
}
ModKind::Unloaded => {}
@ -1121,11 +1122,13 @@ pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
}
pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
let Crate { attrs, items, span, id, is_placeholder: _ } = krate;
let Crate { attrs, items, spans, id, is_placeholder: _ } = krate;
vis.visit_id(id);
visit_attrs(attrs, vis);
items.flat_map_in_place(|item| vis.flat_map_item(item));
vis.visit_span(span);
let ModSpans { inner_span, inject_use_span } = spans;
vis.visit_span(inner_span);
vis.visit_span(inject_use_span);
}
// Mutates one item into possibly many items.
@ -1558,7 +1561,7 @@ impl DummyAstNode for Crate {
Crate {
attrs: Default::default(),
items: Default::default(),
span: Default::default(),
spans: Default::default(),
id: DUMMY_NODE_ID,
is_placeholder: Default::default(),
}

2
compiler/rustc_ast_lowering/src/item.rs
View file

@ -291,7 +291,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
})
}
ItemKind::Mod(_, ref mod_kind) => match mod_kind {
ModKind::Loaded(items, _, inner_span) => {
ModKind::Loaded(items, _, ModSpans { inner_span, inject_use_span: _ }) => {
hir::ItemKind::Mod(self.lower_mod(items, *inner_span))
}
ModKind::Unloaded => panic!("`mod` items should have been loaded by now"),

2
compiler/rustc_ast_lowering/src/lib.rs
View file

@ -452,7 +452,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
visit::walk_crate(&mut item::ItemLowerer { lctx: &mut self }, c);
self.with_hir_id_owner(CRATE_NODE_ID, |lctx| {
let module = lctx.lower_mod(&c.items, c.span);
let module = lctx.lower_mod(&c.items, c.spans.inner_span);
lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs);
hir::OwnerNode::Crate(lctx.arena.alloc(module))
});

5
compiler/rustc_builtin_macros/src/test_harness.rs
View file

@ -112,7 +112,7 @@ impl<'a> MutVisitor for TestHarnessGenerator<'a> {
fn visit_crate(&mut self, c: &mut ast::Crate) {
let prev_tests = mem::take(&mut self.tests);
noop_visit_crate(c, self);
self.add_test_cases(ast::CRATE_NODE_ID, c.span, prev_tests);
self.add_test_cases(ast::CRATE_NODE_ID, c.spans.inner_span, prev_tests);
// Create a main function to run our tests
c.items.push(mk_main(&mut self.cx));
@ -129,7 +129,8 @@ impl<'a> MutVisitor for TestHarnessGenerator<'a> {
// We don't want to recurse into anything other than mods, since
// mods or tests inside of functions will break things
if let ast::ItemKind::Mod(_, ModKind::Loaded(.., span)) = item.kind {
if let ast::ItemKind::Mod(_, ModKind::Loaded(.., ref spans)) = item.kind {
let ast::ModSpans { inner_span: span, inject_use_span: _ } = *spans;
let prev_tests = mem::take(&mut self.tests);
noop_visit_item_kind(&mut item.kind, self);
self.add_test_cases(item.id, span, prev_tests);

2
compiler/rustc_expand/src/base.rs
View file

@ -67,7 +67,7 @@ impl Annotatable {
Annotatable::Param(ref p) => p.span,
Annotatable::FieldDef(ref sf) => sf.span,
Annotatable::Variant(ref v) => v.span,
Annotatable::Crate(ref c) => c.span,
Annotatable::Crate(ref c) => c.spans.inner_span,
}
}

10
compiler/rustc_expand/src/expand.rs
View file

@ -12,8 +12,8 @@ use rustc_ast::token;
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::visit::{self, AssocCtxt, Visitor};
use rustc_ast::{AssocItemKind, AstLike, AstLikeWrapper, AttrStyle, ExprKind, ForeignItemKind};
use rustc_ast::{Inline, ItemKind, MacArgs, MacStmtStyle, MetaItemKind, ModKind, NestedMetaItem};
use rustc_ast::{NodeId, PatKind, StmtKind, TyKind};
use rustc_ast::{Inline, ItemKind, MacArgs, MacStmtStyle, MetaItemKind, ModKind};
use rustc_ast::{NestedMetaItem, NodeId, PatKind, StmtKind, TyKind};
use rustc_ast_pretty::pprust;
use rustc_data_structures::map_in_place::MapInPlace;
use rustc_data_structures::sync::Lrc;
@ -364,7 +364,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
}
pub fn expand_crate(&mut self, krate: ast::Crate) -> ast::Crate {
let file_path = match self.cx.source_map().span_to_filename(krate.span) {
let file_path = match self.cx.source_map().span_to_filename(krate.spans.inner_span) {
FileName::Real(name) => name
.into_local_path()
.expect("attempting to resolve a file path in an external file"),
@ -1091,7 +1091,7 @@ impl InvocationCollectorNode for P<ast::Item> {
ModKind::Unloaded => {
// We have an outline `mod foo;` so we need to parse the file.
let old_attrs_len = attrs.len();
let ParsedExternalMod { items, inner_span, file_path, dir_path, dir_ownership } =
let ParsedExternalMod { items, spans, file_path, dir_path, dir_ownership } =
parse_external_mod(
&ecx.sess,
ident,
@ -1112,7 +1112,7 @@ impl InvocationCollectorNode for P<ast::Item> {
);
}
*mod_kind = ModKind::Loaded(items, Inline::No, inner_span);
*mod_kind = ModKind::Loaded(items, Inline::No, spans);
node.attrs = attrs;
if node.attrs.len() > old_attrs_len {
// If we loaded an out-of-line module and added some inner attributes,

8
compiler/rustc_expand/src/module.rs
View file

@ -1,6 +1,6 @@
use crate::base::ModuleData;
use rustc_ast::ptr::P;
use rustc_ast::{token, Attribute, Inline, Item};
use rustc_ast::{token, Attribute, Inline, Item, ModSpans};
use rustc_errors::{struct_span_err, DiagnosticBuilder, ErrorGuaranteed};
use rustc_parse::new_parser_from_file;
use rustc_parse::validate_attr;
@ -28,7 +28,7 @@ pub struct ModulePathSuccess {
crate struct ParsedExternalMod {
pub items: Vec<P<Item>>,
pub inner_span: Span,
pub spans: ModSpans,
pub file_path: PathBuf,
pub dir_path: PathBuf,
pub dir_ownership: DirOwnership,
@ -69,13 +69,13 @@ crate fn parse_external_mod(
(items, inner_span, mp.file_path)
};
// (1) ...instead, we return a dummy module.
let (items, inner_span, file_path) =
let (items, spans, file_path) =
result.map_err(|err| err.report(sess, span)).unwrap_or_default();
// Extract the directory path for submodules of the module.
let dir_path = file_path.parent().unwrap_or(&file_path).to_owned();
ParsedExternalMod { items, inner_span, file_path, dir_path, dir_ownership }
ParsedExternalMod { items, spans, file_path, dir_path, dir_ownership }
}
crate fn mod_dir_path(

2
compiler/rustc_expand/src/placeholders.rs
View file

@ -49,7 +49,7 @@ pub fn placeholder(
AstFragmentKind::Crate => AstFragment::Crate(ast::Crate {
attrs: Default::default(),
items: Default::default(),
span,
spans: ast::ModSpans { inner_span: span, ..Default::default() },
id,
is_placeholder: true,
}),

2
compiler/rustc_metadata/src/creader.rs
View file

@ -899,7 +899,7 @@ impl<'a> CrateLoader<'a> {
fn report_unused_deps(&mut self, krate: &ast::Crate) {
// Make a point span rather than covering the whole file
let span = krate.span.shrink_to_lo();
let span = krate.spans.inner_span.shrink_to_lo();
// Complain about anything left over
for (name, entry) in self.sess.opts.externs.iter() {
if let ExternLocation::FoundInLibrarySearchDirectories = entry.location {

2
compiler/rustc_parse/src/lib.rs
View file

@ -331,7 +331,7 @@ pub fn fake_token_stream(sess: &ParseSess, nt: &Nonterminal) -> TokenStream {
pub fn fake_token_stream_for_crate(sess: &ParseSess, krate: &ast::Crate) -> TokenStream {
let source = pprust::crate_to_string_for_macros(krate);
let filename = FileName::macro_expansion_source_code(&source);
parse_stream_from_source_str(filename, source, sess, Some(krate.span))
parse_stream_from_source_str(filename, source, sess, Some(krate.spans.inner_span))
}
pub fn parse_cfg_attr(

11
compiler/rustc_parse/src/parser/item.rs
View file

@ -27,8 +27,8 @@ use tracing::debug;
impl<'a> Parser<'a> {
/// Parses a source module as a crate. This is the main entry point for the parser.
pub fn parse_crate_mod(&mut self) -> PResult<'a, ast::Crate> {
let (attrs, items, span) = self.parse_mod(&token::Eof)?;
Ok(ast::Crate { attrs, items, span, id: DUMMY_NODE_ID, is_placeholder: false })
let (attrs, items, spans) = self.parse_mod(&token::Eof)?;
Ok(ast::Crate { attrs, items, spans, id: DUMMY_NODE_ID, is_placeholder: false })
}
/// Parses a `mod <foo> { ... }` or `mod <foo>;` item.
@ -52,10 +52,11 @@ impl<'a> Parser<'a> {
pub fn parse_mod(
&mut self,
term: &TokenKind,
) -> PResult<'a, (Vec<Attribute>, Vec<P<Item>>, Span)> {
) -> PResult<'a, (Vec<Attribute>, Vec<P<Item>>, ModSpans)> {
let lo = self.token.span;
let attrs = self.parse_inner_attributes()?;
let post_attr_lo = self.token.span;
let mut items = vec![];
while let Some(item) = self.parse_item(ForceCollect::No)? {
items.push(item);
@ -72,7 +73,9 @@ impl<'a> Parser<'a> {
}
}
Ok((attrs, items, lo.to(self.prev_token.span)))
let inject_use_span = post_attr_lo.data().with_hi(post_attr_lo.lo());
let mod_spans = ModSpans { inner_span: lo.to(self.prev_token.span), inject_use_span };
Ok((attrs, items, mod_spans))
}
}

113
compiler/rustc_resolve/src/lib.rs
View file

@ -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();

4
compiler/rustc_typeck/src/check/method/suggest.rs
View file

@ -2011,6 +2011,10 @@ pub fn all_traits(tcx: TyCtxt<'_>) -> Vec<TraitInfo> {
}
fn find_use_placement<'tcx>(tcx: TyCtxt<'tcx>, target_module: LocalDefId) -> (Option<Span>, bool) {
// FIXME(#94854): this code uses an out-of-date method for inferring a span
// to suggest. It would be better to thread the ModSpans from the AST into
// the HIR, and then use that to drive the suggestion here.
let mut span = None;
let mut found_use = false;
let (module, _, _) = tcx.hir().get_module(target_module);