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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11
compiler/rustc_middle/src/query/mod.rs
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@ -54,7 +54,7 @@ use crate::ty::{
};
use rustc_arena::TypedArena;
use rustc_ast as ast;
use rustc_ast::expand::allocator::AllocatorKind;
use rustc_ast::expand::{allocator::AllocatorKind, StrippedCfgItem};
use rustc_attr as attr;
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxIndexMap, FxIndexSet};
@ -2173,6 +2173,15 @@ rustc_queries! {
query check_tys_might_be_eq(arg: Canonical<'tcx, (ty::ParamEnv<'tcx>, Ty<'tcx>, Ty<'tcx>)>) -> Result<(), NoSolution> {
desc { "check whether two const param are definitely not equal to eachother"}
}
/// Get all item paths that were stripped by a `#[cfg]` in a particular crate.
/// Should not be called for the local crate before the resolver outputs are created, as it
/// is only fed there.
query stripped_cfg_items(cnum: CrateNum) -> &'tcx [StrippedCfgItem] {
feedable
desc { "getting cfg-ed out item names" }
separate_provide_extern
}
}
rustc_query_append! { define_callbacks! }