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Auto merge of #12041 - jonas-schievink:prefer-core-cfg-attr-no-std, r=jonas-schievink
feat: prefer core/alloc over std in auto-imports if `#[no_std]` is conditional
We already did this if `#![no_std]` was present, this PR makes it work with `#![cfg_attr(not(test), no_std)]` too, which is very common in libraries.
Fixes https://github.com/rust-lang/rust-analyzer/issues/12035
cc https://github.com/rust-lang/rust-analyzer/issues/10718
| -rw-r--r-- | crates/hir_def/src/db.rs | 39 | ||||
| -rw-r--r-- | crates/hir_def/src/find_path.rs | 31 |
2 files changed, 66 insertions, 4 deletions
diff --git a/crates/hir_def/src/db.rs b/crates/hir_def/src/db.rs index 74bb7472d5..df6dcb024b 100644 --- a/crates/hir_def/src/db.rs +++ b/crates/hir_def/src/db.rs @@ -18,7 +18,7 @@ use crate::{ generics::GenericParams, import_map::ImportMap, intern::Interned, - item_tree::ItemTree, + item_tree::{AttrOwner, ItemTree}, lang_item::{LangItemTarget, LangItems}, nameres::DefMap, visibility::{self, Visibility}, @@ -184,6 +184,8 @@ pub trait DefDatabase: InternDatabase + AstDatabase + Upcast<dyn AstDatabase> { #[salsa::transparent] fn crate_limits(&self, crate_id: CrateId) -> CrateLimits; + + fn crate_supports_no_std(&self, crate_id: CrateId) -> bool; } fn crate_def_map_wait(db: &dyn DefDatabase, krate: CrateId) -> Arc<DefMap> { @@ -204,3 +206,38 @@ fn crate_limits(db: &dyn DefDatabase, crate_id: CrateId) -> CrateLimits { recursion_limit: def_map.recursion_limit().unwrap_or(128), } } + +fn crate_supports_no_std(db: &dyn DefDatabase, crate_id: CrateId) -> bool { + let file = db.crate_graph()[crate_id].root_file_id; + let item_tree = db.file_item_tree(file.into()); + let attrs = item_tree.raw_attrs(AttrOwner::TopLevel); + for attr in &**attrs { + match attr.path().as_ident().and_then(|id| id.as_text()) { + Some(ident) if ident == "no_std" => return true, + Some(ident) if ident == "cfg_attr" => {} + _ => continue, + } + + // This is a `cfg_attr`; check if it could possibly expand to `no_std`. + // Syntax is: `#[cfg_attr(condition(cfg, style), attr0, attr1, <...>)]` + let tt = match attr.token_tree_value() { + Some(tt) => &tt.token_trees, + None => continue, + }; + + let segments = tt.split(|tt| match tt { + tt::TokenTree::Leaf(tt::Leaf::Punct(p)) if p.char == ',' => true, + _ => false, + }); + for output in segments.skip(1) { + match output { + [tt::TokenTree::Leaf(tt::Leaf::Ident(ident))] if ident.text == "no_std" => { + return true + } + _ => {} + } + } + } + + false +} diff --git a/crates/hir_def/src/find_path.rs b/crates/hir_def/src/find_path.rs index bb89b8cff4..89e961f84f 100644 --- a/crates/hir_def/src/find_path.rs +++ b/crates/hir_def/src/find_path.rs @@ -43,8 +43,7 @@ impl ModPathExt for ModPath { self.segments().first() == Some(&known::std) } - // When std library is present, paths starting with `std::` - // should be preferred over paths starting with `core::` and `alloc::` + // Can we replace the first segment with `std::` and still get a valid, identical path? fn can_start_with_std(&self) -> bool { let first_segment = self.segments().first(); first_segment == Some(&known::alloc) || first_segment == Some(&known::core) @@ -203,7 +202,7 @@ fn find_path_inner_( } // - otherwise, look for modules containing (reexporting) it and import it from one of those - let prefer_no_std = db.attrs(crate_root.into()).by_key("no_std").exists(); + let prefer_no_std = db.crate_supports_no_std(crate_root.krate); let mut best_path = None; let mut best_path_len = max_len; @@ -839,6 +838,32 @@ pub mod fmt { "core::fmt::Error", "core::fmt::Error", ); + + // Should also work (on a best-effort basis) if `no_std` is conditional. + check_found_path( + r#" +//- /main.rs crate:main deps:core,std +#![cfg_attr(not(test), no_std)] + +$0 + +//- /std.rs crate:std deps:core + +pub mod fmt { + pub use core::fmt::Error; +} + +//- /zzz.rs crate:core + +pub mod fmt { + pub struct Error; +} + "#, + "core::fmt::Error", + "core::fmt::Error", + "core::fmt::Error", + "core::fmt::Error", + ); } #[test] |