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
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12
compiler/rustc_resolve/src/macros.rs
View file

@ -6,6 +6,7 @@ use crate::Namespace::*;
use crate::{BuiltinMacroState, Determinacy};
use crate::{DeriveData, Finalize, ParentScope, ResolutionError, Resolver, ScopeSet};
use crate::{ModuleKind, ModuleOrUniformRoot, NameBinding, PathResult, Segment};
use rustc_ast::expand::StrippedCfgItem;
use rustc_ast::{self as ast, attr, Inline, ItemKind, ModKind, NodeId};
use rustc_ast_pretty::pprust;
use rustc_attr::StabilityLevel;
@ -465,6 +466,10 @@ impl<'a, 'tcx> ResolverExpand for Resolver<'a, 'tcx> {
self.proc_macros.push(id)
}
fn append_stripped_cfg_item(&mut self, parent_node: NodeId, name: Ident, cfg: ast::MetaItem) {
self.stripped_cfg_items.push(StrippedCfgItem { parent_module: parent_node, name, cfg });
}
fn registered_tools(&self) -> &RegisteredTools {
&self.registered_tools
}
@ -721,7 +726,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
}
path_res @ (PathResult::NonModule(..) | PathResult::Failed { .. }) => {
let mut suggestion = None;
let (span, label) = if let PathResult::Failed { span, label, .. } = path_res {
let (span, label, module) = if let PathResult::Failed { span, label, module, .. } = path_res {
// try to suggest if it's not a macro, maybe a function
if let PathResult::NonModule(partial_res) = self.maybe_resolve_path(&path, Some(ValueNS), &parent_scope)
&& partial_res.unresolved_segments() == 0 {
@ -733,7 +738,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
Applicability::MaybeIncorrect
));
}
(span, label)
(span, label, module)
} else {
(
path_span,
@ -742,11 +747,12 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
kind.article(),
kind.descr()
),
None,
)
};
self.report_error(
span,
ResolutionError::FailedToResolve { label, suggestion },
ResolutionError::FailedToResolve { last_segment: path.last().map(|segment| segment.ident.name), label, suggestion, module },
);
}
PathResult::Module(..) | PathResult::Indeterminate => unreachable!(),