bjoernager/rust
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Remember names of cfg-ed out items to mention them in diagnostics

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`#[cfg]`s are frequently used to gate crate content behind cargo
features. This can lead to very confusing errors when features are
missing. For example, `serde` doesn't have the `derive` feature by
default. Therefore, `serde::Serialize` fails to resolve with a generic
error, even though the macro is present in the docs.

This commit adds a list of all stripped item names to metadata. This is
filled during macro expansion and then, through a fed query, persisted
in metadata. The downstream resolver can then access the metadata to
look at possible candidates for mentioning in the errors.

This slightly increases metadata (800k->809k for the feature-heavy
windows crate), but not enough to really matter.
This commit is contained in:
Nilstrieb 2023-03-10 22:39:14 +01:00
parent 642c92e630
commit a647ba250a
30 changed files with 599 additions and 84 deletions
Download patch file Download diff file Expand all files Collapse all files

4
compiler/rustc_expand/src/base.rs
View file

@ -947,6 +947,8 @@ pub trait ResolverExpand {
/// HIR proc macros items back to their harness items.
fn declare_proc_macro(&mut self, id: NodeId);
fn append_stripped_cfg_item(&mut self, parent_node: NodeId, name: Ident, cfg: ast::MetaItem);
/// Tools registered with `#![register_tool]` and used by tool attributes and lints.
fn registered_tools(&self) -> &RegisteredTools;
}
@ -965,7 +967,7 @@ pub trait LintStoreExpand {
type LintStoreExpandDyn<'a> = Option<&'a (dyn LintStoreExpand + 'a)>;
#[derive(Clone, Default)]
#[derive(Debug, Clone, Default)]
pub struct ModuleData {
/// Path to the module starting from the crate name, like `my_crate::foo::bar`.
pub mod_path: Vec<Ident>,

20
compiler/rustc_expand/src/config.rs
View file

@ -416,20 +416,28 @@ impl<'a> StripUnconfigured<'a> {
/// Determines if a node with the given attributes should be included in this configuration.
fn in_cfg(&self, attrs: &[Attribute]) -> bool {
attrs.iter().all(|attr| !is_cfg(attr) || self.cfg_true(attr))
attrs.iter().all(|attr| !is_cfg(attr) || self.cfg_true(attr).0)
}
pub(crate) fn cfg_true(&self, attr: &Attribute) -> bool {
pub(crate) fn cfg_true(&self, attr: &Attribute) -> (bool, Option<MetaItem>) {
let meta_item = match validate_attr::parse_meta(&self.sess.parse_sess, attr) {
Ok(meta_item) => meta_item,
Err(mut err) => {
err.emit();
return true;
return (true, None);
}
};
parse_cfg(&meta_item, &self.sess).map_or(true, |meta_item| {
attr::cfg_matches(&meta_item, &self.sess.parse_sess, self.lint_node_id, self.features)
})
(
parse_cfg(&meta_item, &self.sess).map_or(true, |meta_item| {
attr::cfg_matches(
&meta_item,
&self.sess.parse_sess,
self.lint_node_id,
self.features,
)
}),
Some(meta_item),
)
}
/// If attributes are not allowed on expressions, emit an error for `attr`

49
compiler/rustc_expand/src/expand.rs
View file

@ -1042,6 +1042,12 @@ trait InvocationCollectorNode: HasAttrs + HasNodeId + Sized {
fn expand_cfg_false(&mut self, collector: &mut InvocationCollector<'_, '_>, span: Span) {
collector.cx.emit_err(RemoveNodeNotSupported { span, descr: Self::descr() });
}
/// All of the names (items) declared by this node.
/// This is an approximation and should only be used for diagnostics.
fn declared_names(&self) -> Vec<Ident> {
vec![]
}
}
impl InvocationCollectorNode for P<ast::Item> {
@ -1148,6 +1154,27 @@ impl InvocationCollectorNode for P<ast::Item> {
collector.cx.current_expansion.module = orig_module;
res
}
fn declared_names(&self) -> Vec<Ident> {
if let ItemKind::Use(ut) = &self.kind {
fn collect_use_tree_leaves(ut: &ast::UseTree, idents: &mut Vec<Ident>) {
match &ut.kind {
ast::UseTreeKind::Glob => {}
ast::UseTreeKind::Simple(_) => idents.push(ut.ident()),
ast::UseTreeKind::Nested(nested) => {
for (ut, _) in nested {
collect_use_tree_leaves(&ut, idents);
}
}
}
}
let mut idents = Vec::new();
collect_use_tree_leaves(&ut, &mut idents);
return idents;
}
vec![self.ident]
}
}
struct TraitItemTag;
@ -1685,8 +1712,8 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
node: &mut impl HasAttrs,
attr: ast::Attribute,
pos: usize,
) -> bool {
let res = self.cfg().cfg_true(&attr);
) -> (bool, Option<ast::MetaItem>) {
let (res, meta_item) = self.cfg().cfg_true(&attr);
if res {
// FIXME: `cfg(TRUE)` attributes do not currently remove themselves during expansion,
// and some tools like rustdoc and clippy rely on that. Find a way to remove them
@ -1694,7 +1721,8 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
self.cx.expanded_inert_attrs.mark(&attr);
node.visit_attrs(|attrs| attrs.insert(pos, attr));
}
res
(res, meta_item)
}
fn expand_cfg_attr(&self, node: &mut impl HasAttrs, attr: &ast::Attribute, pos: usize) {
@ -1715,9 +1743,20 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
return match self.take_first_attr(&mut node) {
Some((attr, pos, derives)) => match attr.name_or_empty() {
sym::cfg => {
if self.expand_cfg_true(&mut node, attr, pos) {
let (res, meta_item) = self.expand_cfg_true(&mut node, attr, pos);
if res {
continue;
}
if let Some(meta_item) = meta_item {
for name in node.declared_names() {
self.cx.resolver.append_stripped_cfg_item(
self.cx.current_expansion.lint_node_id,
name,
meta_item.clone(),
)
}
}
Default::default()
}
sym::cfg_attr => {
@ -1761,7 +1800,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
Some((attr, pos, derives)) => match attr.name_or_empty() {
sym::cfg => {
let span = attr.span;
if self.expand_cfg_true(node, attr, pos) {
if self.expand_cfg_true(node, attr, pos).0 {
continue;
}