rust-analyzer

diff --git a/crates/hir-def/src/nameres.rs b/crates/hir-def/src/nameres.rs
index 45f631936d..fc8444394c 100644
--- a/crates/hir-def/src/nameres.rs
+++ b/crates/hir-def/src/nameres.rs

@@ -64,7 +64,7 @@ use hir_expand::{name::Name, InFile, MacroCallId, MacroDefId};

use itertools::Itertools;

use la_arena::Arena;

use profile::Count;

-use rustc_hash::FxHashMap;

+use rustc_hash::{FxHashMap, FxHashSet};

use stdx::format_to;

use syntax::{ast, SmolStr};

@@ -114,6 +114,8 @@ pub struct DefMap {

registered_attrs: Vec<SmolStr>,

/// Custom tool modules registered with `#![register_tool]`.

registered_tools: Vec<SmolStr>,

+ /// Unstable features of Rust enabled with `#![feature(A, B)]`.

+ unstable_features: FxHashSet<SmolStr>,

edition: Edition,

recursion_limit: Option<u32>,

@@ -284,6 +286,7 @@ impl DefMap {

modules,

registered_attrs: Vec::new(),

registered_tools: Vec::new(),

+ unstable_features: FxHashSet::default(),

diagnostics: Vec::new(),

}

@@ -314,6 +317,10 @@ impl DefMap {

&self.registered_attrs

}

+ pub fn is_unstable_feature_enabled(&self, feature: &str) -> bool {

+ self.unstable_features.contains(feature)

+ }

pub fn root(&self) -> LocalModuleId {

self.root

}

@@ -483,6 +490,7 @@ impl DefMap {

registered_tools,

fn_proc_macro_mapping,

derive_helpers_in_scope,

+ unstable_features,

proc_macro_loading_error: _,

block: _,

edition: _,

@@ -500,6 +508,7 @@ impl DefMap {

registered_tools.shrink_to_fit();

fn_proc_macro_mapping.shrink_to_fit();

derive_helpers_in_scope.shrink_to_fit();

+ unstable_features.shrink_to_fit();

for (_, module) in modules.iter_mut() {

module.children.shrink_to_fit();

module.scope.shrink_to_fit();

diff --git a/crates/hir-def/src/nameres/collector.rs b/crates/hir-def/src/nameres/collector.rs
index 8a6bb929c3..ee27aa2554 100644
--- a/crates/hir-def/src/nameres/collector.rs
+++ b/crates/hir-def/src/nameres/collector.rs

@@ -294,6 +294,17 @@ impl DefCollector<'_> {

continue;

}

+ if *attr_name == hir_expand::name![feature] {

+ let features =

+ attr.parse_path_comma_token_tree().into_iter().flatten().filter_map(

+ |feat| match feat.segments() {

+ [name] => Some(name.to_smol_str()),

+ _ => None,

+ },

+ );

+ self.def_map.unstable_features.extend(features);

+ }

let attr_is_register_like = *attr_name == hir_expand::name![register_attr]

|| *attr_name == hir_expand::name![register_tool];

if !attr_is_register_like {

diff --git a/crates/hir-expand/src/name.rs b/crates/hir-expand/src/name.rs
index 2b859f7750..4ce21a5796 100644
--- a/crates/hir-expand/src/name.rs
+++ b/crates/hir-expand/src/name.rs

@@ -336,6 +336,7 @@ pub mod known {

test,

test_case,

recursion_limit,

+ feature,

// Safe intrinsics

abort,

add_with_overflow,

diff --git a/crates/hir-ty/src/diagnostics/match_check/usefulness.rs b/crates/hir-ty/src/diagnostics/match_check/usefulness.rs
index 4bb4ff8f10..c4d709a975 100644
--- a/crates/hir-ty/src/diagnostics/match_check/usefulness.rs
+++ b/crates/hir-ty/src/diagnostics/match_check/usefulness.rs

@@ -274,7 +274,6 @@

use std::iter::once;

use hir_def::{AdtId, DefWithBodyId, HasModule, ModuleId};

-use once_cell::unsync::OnceCell;

use smallvec::{smallvec, SmallVec};

use typed_arena::Arena;

@@ -290,7 +289,7 @@ pub(crate) struct MatchCheckCtx<'a, 'p> {

pub(crate) db: &'a dyn HirDatabase,

/// Lowered patterns from arms plus generated by the check.

pub(crate) pattern_arena: &'p Arena<DeconstructedPat<'p>>,

- feature_exhaustive_patterns: OnceCell<bool>,

+ exhaustive_patterns: bool,

}

impl<'a, 'p> MatchCheckCtx<'a, 'p> {

@@ -300,7 +299,9 @@ impl<'a, 'p> MatchCheckCtx<'a, 'p> {

db: &'a dyn HirDatabase,

pattern_arena: &'p Arena<DeconstructedPat<'p>>,

) -> Self {

- Self { module, body, db, pattern_arena, feature_exhaustive_patterns: Default::default() }

+ let def_map = db.crate_def_map(module.krate());

+ let exhaustive_patterns = def_map.is_unstable_feature_enabled("exhaustive_patterns");

+ Self { module, body, db, pattern_arena, exhaustive_patterns }

}

pub(super) fn is_uninhabited(&self, ty: &Ty) -> bool {

@@ -326,20 +327,7 @@ impl<'a, 'p> MatchCheckCtx<'a, 'p> {

// Rust's unstable feature described as "Allows exhaustive pattern matching on types that contain uninhabited types."

pub(super) fn feature_exhaustive_patterns(&self) -> bool {

- *self.feature_exhaustive_patterns.get_or_init(|| {

- let def_map = self.db.crate_def_map(self.module.krate());

- let root_mod = def_map.module_id(def_map.root());

- let rood_attrs = self.db.attrs(root_mod.into());

- let mut nightly_features = rood_attrs

- .by_key("feature")

- .attrs()

- .map(|attr| attr.parse_path_comma_token_tree())

- .flatten()

- .flatten();

- nightly_features.any(

- |feat| matches!(feat.segments(), [name] if name.to_smol_str() == "exhaustive_patterns"),

- )

- })

+ self.exhaustive_patterns

}