Merge #1928

1928: Support `#[cfg(..)]` r=matklad a=oxalica

This PR implement `#[cfg(..)]` conditional compilation. It read default cfg options from `rustc --print cfg` with also hard-coded `test` and `debug_assertion` enabled.
Front-end settings are **not** included in this PR.

There is also a known issue that inner control attributes are totally ignored. I think it is **not** a part of `cfg` and create a separated issue for it. #1949

Fixes #1920 

Related: #1073 


Co-authored-by: uHOOCCOOHu <hooccooh1896@gmail.com>
Co-authored-by: oxalica <oxalicc@pm.me>

crates/ra_hir/src/attr.rs

@@ -0,0 +1,80 @@
+//! A higher level attributes based on TokenTree, with also some shortcuts.
+
+use std::sync::Arc;
+
+use mbe::ast_to_token_tree;
+use ra_cfg::CfgOptions;
+use ra_syntax::{
+    ast::{self, AstNode, AttrsOwner},
+    SmolStr,
+};
+use tt::Subtree;
+
+use crate::{db::AstDatabase, path::Path, HirFileId, Source};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub(crate) struct Attr {
+    pub(crate) path: Path,
+    pub(crate) input: Option<AttrInput>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum AttrInput {
+    Literal(SmolStr),
+    TokenTree(Subtree),
+}
+
+impl Attr {
+    pub(crate) fn from_src(
+        Source { file_id, ast }: Source<ast::Attr>,
+        db: &impl AstDatabase,
+    ) -> Option<Attr> {
+        let path = Path::from_src(Source { file_id, ast: ast.path()? }, db)?;
+        let input = match ast.input() {
+            None => None,
+            Some(ast::AttrInput::Literal(lit)) => {
+                // FIXME: escape? raw string?
+                let value = lit.syntax().first_token()?.text().trim_matches('"').into();
+                Some(AttrInput::Literal(value))
+            }
+            Some(ast::AttrInput::TokenTree(tt)) => {
+                Some(AttrInput::TokenTree(ast_to_token_tree(&tt)?.0))
+            }
+        };
+
+        Some(Attr { path, input })
+    }
+
+    pub(crate) fn from_attrs_owner(
+        file_id: HirFileId,
+        owner: &dyn AttrsOwner,
+        db: &impl AstDatabase,
+    ) -> Option<Arc<[Attr]>> {
+        let mut attrs = owner.attrs().peekable();
+        if attrs.peek().is_none() {
+            // Avoid heap allocation
+            return None;
+        }
+        Some(attrs.flat_map(|ast| Attr::from_src(Source { file_id, ast }, db)).collect())
+    }
+
+    pub(crate) fn is_simple_atom(&self, name: &str) -> bool {
+        // FIXME: Avoid cloning
+        self.path.as_ident().map_or(false, |s| s.to_string() == name)
+    }
+
+    pub(crate) fn as_cfg(&self) -> Option<&Subtree> {
+        if self.is_simple_atom("cfg") {
+            match &self.input {
+                Some(AttrInput::TokenTree(subtree)) => Some(subtree),
+                _ => None,
+            }
+        } else {
+            None
+        }
+    }
+
+    pub(crate) fn is_cfg_enabled(&self, cfg_options: &CfgOptions) -> Option<bool> {
+        cfg_options.is_cfg_enabled(self.as_cfg()?)
+    }
+}

crates/ra_hir/src/impl_block.rs

@@ -4,12 +4,14 @@ use rustc_hash::FxHashMap;
 use std::sync::Arc;
 
 use ra_arena::{impl_arena_id, map::ArenaMap, Arena, RawId};
+use ra_cfg::CfgOptions;
 use ra_syntax::{
     ast::{self, AstNode},
     AstPtr,
 };
 
 use crate::{
+    attr::Attr,
     code_model::{Module, ModuleSource},
     db::{AstDatabase, DefDatabase, HirDatabase},
     generics::HasGenericParams,
@@ -176,6 +178,7 @@ pub struct ModuleImplBlocks {
 impl ModuleImplBlocks {
     fn collect(
         db: &(impl DefDatabase + AstDatabase),
+        cfg_options: &CfgOptions,
         module: Module,
         source_map: &mut ImplSourceMap,
     ) -> Self {
@@ -188,11 +191,11 @@ impl ModuleImplBlocks {
         let src = m.module.definition_source(db);
         match &src.ast {
             ModuleSource::SourceFile(node) => {
-                m.collect_from_item_owner(db, source_map, node, src.file_id)
+                m.collect_from_item_owner(db, cfg_options, source_map, node, src.file_id)
             }
             ModuleSource::Module(node) => {
                 let item_list = node.item_list().expect("inline module should have item list");
-                m.collect_from_item_owner(db, source_map, &item_list, src.file_id)
+                m.collect_from_item_owner(db, cfg_options, source_map, &item_list, src.file_id)
             }
         };
         m
@@ -201,6 +204,7 @@ impl ModuleImplBlocks {
     fn collect_from_item_owner(
         &mut self,
         db: &(impl DefDatabase + AstDatabase),
+        cfg_options: &CfgOptions,
         source_map: &mut ImplSourceMap,
         owner: &dyn ast::ModuleItemOwner,
         file_id: HirFileId,
@@ -208,6 +212,13 @@ impl ModuleImplBlocks {
         for item in owner.items_with_macros() {
             match item {
                 ast::ItemOrMacro::Item(ast::ModuleItem::ImplBlock(impl_block_ast)) => {
+                    let attrs = Attr::from_attrs_owner(file_id, &impl_block_ast, db);
+                    if attrs.map_or(false, |attrs| {
+                        attrs.iter().any(|attr| attr.is_cfg_enabled(cfg_options) == Some(false))
+                    }) {
+                        continue;
+                    }
+
                     let impl_block = ImplData::from_ast(db, file_id, self.module, &impl_block_ast);
                     let id = self.impls.alloc(impl_block);
                     for &impl_item in &self.impls[id].items {
@@ -218,6 +229,13 @@ impl ModuleImplBlocks {
                 }
                 ast::ItemOrMacro::Item(_) => (),
                 ast::ItemOrMacro::Macro(macro_call) => {
+                    let attrs = Attr::from_attrs_owner(file_id, &macro_call, db);
+                    if attrs.map_or(false, |attrs| {
+                        attrs.iter().any(|attr| attr.is_cfg_enabled(cfg_options) == Some(false))
+                    }) {
+                        continue;
+                    }
+
                     //FIXME: we should really cut down on the boilerplate required to process a macro
                     let ast_id = db.ast_id_map(file_id).ast_id(&macro_call).with_file_id(file_id);
                     if let Some(path) = macro_call
@@ -231,7 +249,13 @@ impl ModuleImplBlocks {
                             if let Some(item_list) =
                                 db.parse_or_expand(file_id).and_then(ast::MacroItems::cast)
                             {
-                                self.collect_from_item_owner(db, source_map, &item_list, file_id)
+                                self.collect_from_item_owner(
+                                    db,
+                                    cfg_options,
+                                    source_map,
+                                    &item_list,
+                                    file_id,
+                                )
                             }
                         }
                     }
@@ -246,8 +270,10 @@ pub(crate) fn impls_in_module_with_source_map_query(
     module: Module,
 ) -> (Arc<ModuleImplBlocks>, Arc<ImplSourceMap>) {
     let mut source_map = ImplSourceMap::default();
+    let crate_graph = db.crate_graph();
+    let cfg_options = crate_graph.cfg_options(module.krate.crate_id());
 
-    let result = ModuleImplBlocks::collect(db, module, &mut source_map);
+    let result = ModuleImplBlocks::collect(db, cfg_options, module, &mut source_map);
     (Arc::new(result), Arc::new(source_map))
 }
 

crates/ra_hir/src/lib.rs

@@ -44,6 +44,7 @@ mod traits;
 mod type_alias;
 mod type_ref;
 mod ty;
+mod attr;
 mod impl_block;
 mod expr;
 mod lang_item;

crates/ra_hir/src/mock.rs

@@ -3,6 +3,7 @@
 use std::{panic, sync::Arc};
 
 use parking_lot::Mutex;
+use ra_cfg::CfgOptions;
 use ra_db::{
     salsa, CrateGraph, CrateId, Edition, FileId, FilePosition, SourceDatabase, SourceRoot,
     SourceRootId,
@@ -74,13 +75,13 @@ impl MockDatabase {
     pub fn set_crate_graph_from_fixture(&mut self, graph: CrateGraphFixture) {
         let mut ids = FxHashMap::default();
         let mut crate_graph = CrateGraph::default();
-        for (crate_name, (crate_root, edition, _)) in graph.0.iter() {
+        for (crate_name, (crate_root, edition, cfg_options, _)) in graph.0.iter() {
             let crate_root = self.file_id_of(&crate_root);
-            let crate_id = crate_graph.add_crate_root(crate_root, *edition);
+            let crate_id = crate_graph.add_crate_root(crate_root, *edition, cfg_options.clone());
             Arc::make_mut(&mut self.crate_names).insert(crate_id, crate_name.clone());
             ids.insert(crate_name, crate_id);
         }
-        for (crate_name, (_, _, deps)) in graph.0.iter() {
+        for (crate_name, (_, _, _, deps)) in graph.0.iter() {
             let from = ids[crate_name];
             for dep in deps {
                 let to = ids[dep];
@@ -184,7 +185,7 @@ impl MockDatabase {
 
         if is_crate_root {
             let mut crate_graph = CrateGraph::default();
-            crate_graph.add_crate_root(file_id, Edition::Edition2018);
+            crate_graph.add_crate_root(file_id, Edition::Edition2018, CfgOptions::default());
             self.set_crate_graph(Arc::new(crate_graph));
         }
         file_id
@@ -268,19 +269,27 @@ impl MockDatabase {
 }
 
 #[derive(Default)]
-pub struct CrateGraphFixture(pub Vec<(String, (String, Edition, Vec<String>))>);
+pub struct CrateGraphFixture(pub Vec<(String, (String, Edition, CfgOptions, Vec<String>))>);
 
 #[macro_export]
 macro_rules! crate_graph {
-    ($($crate_name:literal: ($crate_path:literal, $($edition:literal,)? [$($dep:literal),*]),)*) => {{
+    ($(
+        $crate_name:literal: (
+            $crate_path:literal,
+            $($edition:literal,)?
+            [$($dep:literal),*]
+            $(,$cfg:expr)?
+        ),
+    )*) => {{
         let mut res = $crate::mock::CrateGraphFixture::default();
         $(
             #[allow(unused_mut, unused_assignments)]
             let mut edition = ra_db::Edition::Edition2018;
             $(edition = ra_db::Edition::from_string($edition);)?
+            let cfg_options = { ::ra_cfg::CfgOptions::default() $(; $cfg)? };
             res.0.push((
                 $crate_name.to_string(),
-                ($crate_path.to_string(), edition, vec![$($dep.to_string()),*])
+                ($crate_path.to_string(), edition, cfg_options, vec![$($dep.to_string()),*])
             ));
         )*
         res

crates/ra_hir/src/nameres/collector.rs

@@ -1,5 +1,6 @@
 //! FIXME: write short doc here
 
+use ra_cfg::CfgOptions;
 use ra_db::FileId;
 use ra_syntax::{ast, SmolStr};
 use rustc_hash::FxHashMap;
@@ -35,6 +36,9 @@ pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> C
         }
     }
 
+    let crate_graph = db.crate_graph();
+    let cfg_options = crate_graph.cfg_options(def_map.krate().crate_id());
+
     let mut collector = DefCollector {
         db,
         def_map,
@@ -42,6 +46,7 @@ pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> C
         unresolved_imports: Vec::new(),
         unexpanded_macros: Vec::new(),
         macro_stack_monitor: MacroStackMonitor::default(),
+        cfg_options,
     };
     collector.collect();
     collector.finish()
@@ -76,8 +81,8 @@ impl MacroStackMonitor {
 }
 
 /// Walks the tree of module recursively
-struct DefCollector<DB> {
-    db: DB,
+struct DefCollector<'a, DB> {
+    db: &'a DB,
     def_map: CrateDefMap,
     glob_imports: FxHashMap<CrateModuleId, Vec<(CrateModuleId, raw::ImportId)>>,
     unresolved_imports: Vec<(CrateModuleId, raw::ImportId, raw::ImportData)>,
@@ -86,9 +91,11 @@ struct DefCollector<DB> {
     /// Some macro use `$tt:tt which mean we have to handle the macro perfectly
     /// To prevent stack overflow, we add a deep counter here for prevent that.
     macro_stack_monitor: MacroStackMonitor,
+
+    cfg_options: &'a CfgOptions,
 }
 
-impl<'a, DB> DefCollector<&'a DB>
+impl<DB> DefCollector<'_, DB>
 where
     DB: DefDatabase,
 {
@@ -506,7 +513,7 @@ struct ModCollector<'a, D> {
     parent_module: Option<ParentModule<'a>>,
 }
 
-impl<DB> ModCollector<'_, &'_ mut DefCollector<&'_ DB>>
+impl<DB> ModCollector<'_, &'_ mut DefCollector<'_, DB>>
 where
     DB: DefDatabase,
 {
@@ -523,24 +530,27 @@ where
         // `#[macro_use] extern crate` is hoisted to imports macros before collecting
         // any other items.
         for item in items {
-            if let raw::RawItem::Import(import_id) = *item {
-                let import = self.raw_items[import_id].clone();
-                if import.is_extern_crate && import.is_macro_use {
-                    self.def_collector.import_macros_from_extern_crate(self.module_id, &import);
+            if self.is_cfg_enabled(&item.attrs) {
+                if let raw::RawItemKind::Import(import_id) = item.kind {
+                    let import = self.raw_items[import_id].clone();
+                    if import.is_extern_crate && import.is_macro_use {
+                        self.def_collector.import_macros_from_extern_crate(self.module_id, &import);
+                    }
                 }
             }
         }
 
         for item in items {
-            match *item {
-                raw::RawItem::Module(m) => self.collect_module(&self.raw_items[m]),
-                raw::RawItem::Import(import_id) => self.def_collector.unresolved_imports.push((
-                    self.module_id,
-                    import_id,
-                    self.raw_items[import_id].clone(),
-                )),
-                raw::RawItem::Def(def) => self.define_def(&self.raw_items[def]),
-                raw::RawItem::Macro(mac) => self.collect_macro(&self.raw_items[mac]),
+            if self.is_cfg_enabled(&item.attrs) {
+                match item.kind {
+                    raw::RawItemKind::Module(m) => self.collect_module(&self.raw_items[m]),
+                    raw::RawItemKind::Import(import_id) => self
+                        .def_collector
+                        .unresolved_imports
+                        .push((self.module_id, import_id, self.raw_items[import_id].clone())),
+                    raw::RawItemKind::Def(def) => self.define_def(&self.raw_items[def]),
+                    raw::RawItemKind::Macro(mac) => self.collect_macro(&self.raw_items[mac]),
+                }
             }
         }
     }
@@ -703,6 +713,14 @@ where
             self.def_collector.define_legacy_macro(self.module_id, name.clone(), macro_);
         }
     }
+
+    fn is_cfg_enabled(&self, attrs: &raw::Attrs) -> bool {
+        attrs.as_ref().map_or(true, |attrs| {
+            attrs
+                .iter()
+                .all(|attr| attr.is_cfg_enabled(&self.def_collector.cfg_options) != Some(false))
+        })
+    }
 }
 
 fn is_macro_rules(path: &Path) -> bool {
@@ -730,6 +748,7 @@ mod tests {
             unresolved_imports: Vec::new(),
             unexpanded_macros: Vec::new(),
             macro_stack_monitor: monitor,
+            cfg_options: &CfgOptions::default(),
         };
         collector.collect();
         collector.finish()

crates/ra_hir/src/nameres/raw.rs

@@ -10,6 +10,7 @@ use ra_syntax::{
 use test_utils::tested_by;
 
 use crate::{
+    attr::Attr,
     db::{AstDatabase, DefDatabase},
     AsName, AstIdMap, Either, FileAstId, HirFileId, ModuleSource, Name, Path, Source,
 };
@@ -119,8 +120,17 @@ impl Index<Macro> for RawItems {
     }
 }
 
+// Avoid heap allocation on items without attributes.
+pub(super) type Attrs = Option<Arc<[Attr]>>;
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub(super) struct RawItem {
+    pub(super) attrs: Attrs,
+    pub(super) kind: RawItemKind,
+}
+
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub(super) enum RawItem {
+pub(super) enum RawItemKind {
     Module(Module),
     Import(ImportId),
     Def(Def),
@@ -215,6 +225,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
     }
 
     fn add_item(&mut self, current_module: Option<Module>, item: ast::ModuleItem) {
+        let attrs = self.parse_attrs(&item);
         let (kind, name) = match item {
             ast::ModuleItem::Module(module) => {
                 self.add_module(current_module, module);
@@ -263,7 +274,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
         if let Some(name) = name {
             let name = name.as_name();
             let def = self.raw_items.defs.alloc(DefData { name, kind });
-            self.push_item(current_module, RawItem::Def(def))
+            self.push_item(current_module, attrs, RawItemKind::Def(def));
         }
     }
 
@@ -272,8 +283,10 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
             Some(it) => it.as_name(),
             None => return,
         };
+        let attrs = self.parse_attrs(&module);
 
         let ast_id = self.source_ast_id_map.ast_id(&module);
+        // FIXME: cfg_attr
         let is_macro_use = module.has_atom_attr("macro_use");
         if module.has_semi() {
             let attr_path = extract_mod_path_attribute(&module);
@@ -283,7 +296,7 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
                 attr_path,
                 is_macro_use,
             });
-            self.push_item(current_module, RawItem::Module(item));
+            self.push_item(current_module, attrs, RawItemKind::Module(item));
             return;
         }
 
@@ -297,14 +310,16 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
                 is_macro_use,
             });
             self.process_module(Some(item), item_list);
-            self.push_item(current_module, RawItem::Module(item));
+            self.push_item(current_module, attrs, RawItemKind::Module(item));
             return;
         }
         tested_by!(name_res_works_for_broken_modules);
     }
 
     fn add_use_item(&mut self, current_module: Option<Module>, use_item: ast::UseItem) {
+        // FIXME: cfg_attr
         let is_prelude = use_item.has_atom_attr("prelude_import");
+        let attrs = self.parse_attrs(&use_item);
 
         Path::expand_use_item(
             Source { ast: use_item, file_id: self.file_id },
@@ -318,7 +333,12 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
                     is_extern_crate: false,
                     is_macro_use: false,
                 };
-                self.push_import(current_module, import_data, Either::A(AstPtr::new(use_tree)));
+                self.push_import(
+                    current_module,
+                    attrs.clone(),
+                    import_data,
+                    Either::A(AstPtr::new(use_tree)),
+                );
             },
         )
     }
@@ -331,6 +351,8 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
         if let Some(name_ref) = extern_crate.name_ref() {
             let path = Path::from_name_ref(&name_ref);
             let alias = extern_crate.alias().and_then(|a| a.name()).map(|it| it.as_name());
+            let attrs = self.parse_attrs(&extern_crate);
+            // FIXME: cfg_attr
             let is_macro_use = extern_crate.has_atom_attr("macro_use");
             let import_data = ImportData {
                 path,
@@ -340,11 +362,17 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
                 is_extern_crate: true,
                 is_macro_use,
             };
-            self.push_import(current_module, import_data, Either::B(AstPtr::new(&extern_crate)));
+            self.push_import(
+                current_module,
+                attrs,
+                import_data,
+                Either::B(AstPtr::new(&extern_crate)),
+            );
         }
     }
 
     fn add_macro(&mut self, current_module: Option<Module>, m: ast::MacroCall) {
+        let attrs = self.parse_attrs(&m);
         let path = match m
             .path()
             .and_then(|path| Path::from_src(Source { ast: path, file_id: self.file_id }, self.db))
@@ -355,24 +383,26 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
 
         let name = m.name().map(|it| it.as_name());
         let ast_id = self.source_ast_id_map.ast_id(&m);
+        // FIXME: cfg_attr
         let export = m.attrs().filter_map(|x| x.simple_name()).any(|name| name == "macro_export");
 
         let m = self.raw_items.macros.alloc(MacroData { ast_id, path, name, export });
-        self.push_item(current_module, RawItem::Macro(m));
+        self.push_item(current_module, attrs, RawItemKind::Macro(m));
     }
 
     fn push_import(
         &mut self,
         current_module: Option<Module>,
+        attrs: Attrs,
         data: ImportData,
         source: ImportSourcePtr,
     ) {
         let import = self.raw_items.imports.alloc(data);
         self.source_map.insert(import, source);
-        self.push_item(current_module, RawItem::Import(import))
+        self.push_item(current_module, attrs, RawItemKind::Import(import))
     }
 
-    fn push_item(&mut self, current_module: Option<Module>, item: RawItem) {
+    fn push_item(&mut self, current_module: Option<Module>, attrs: Attrs, kind: RawItemKind) {
         match current_module {
             Some(module) => match &mut self.raw_items.modules[module] {
                 ModuleData::Definition { items, .. } => items,
@@ -380,7 +410,11 @@ impl<DB: AstDatabase> RawItemsCollector<&DB> {
             },
             None => &mut self.raw_items.items,
         }
-        .push(item)
+        .push(RawItem { attrs, kind })
+    }
+
+    fn parse_attrs(&self, item: &impl ast::AttrsOwner) -> Attrs {
+        Attr::from_attrs_owner(self.file_id, item, self.db)
     }
 }
 

crates/ra_hir/src/nameres/tests.rs

@@ -7,6 +7,7 @@ mod mod_resolution;
 use std::sync::Arc;
 
 use insta::assert_snapshot;
+use ra_cfg::CfgOptions;
 use ra_db::SourceDatabase;
 use test_utils::covers;
 
@@ -507,3 +508,72 @@ fn values_dont_shadow_extern_crates() {
         ⋮foo: v
     "###);
 }
+
+#[test]
+fn cfg_not_test() {
+    let map = def_map_with_crate_graph(
+        r#"
+        //- /main.rs
+        use {Foo, Bar, Baz};
+        //- /lib.rs
+        #[prelude_import]
+        pub use self::prelude::*;
+        mod prelude {
+            #[cfg(test)]
+            pub struct Foo;
+            #[cfg(not(test))]
+            pub struct Bar;
+            #[cfg(all(not(any()), feature = "foo", feature = "bar", opt = "42"))]
+            pub struct Baz;
+        }
+        "#,
+        crate_graph! {
+            "main": ("/main.rs", ["std"]),
+            "std": ("/lib.rs", []),
+        },
+    );
+
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮Bar: t v
+        ⋮Baz: _
+        ⋮Foo: _
+    "###);
+}
+
+#[test]
+fn cfg_test() {
+    let map = def_map_with_crate_graph(
+        r#"
+        //- /main.rs
+        use {Foo, Bar, Baz};
+        //- /lib.rs
+        #[prelude_import]
+        pub use self::prelude::*;
+        mod prelude {
+            #[cfg(test)]
+            pub struct Foo;
+            #[cfg(not(test))]
+            pub struct Bar;
+            #[cfg(all(not(any()), feature = "foo", feature = "bar", opt = "42"))]
+            pub struct Baz;
+        }
+        "#,
+        crate_graph! {
+            "main": ("/main.rs", ["std"]),
+            "std": ("/lib.rs", [], CfgOptions::default()
+                .atom("test".into())
+                .key_value("feature".into(), "foo".into())
+                .key_value("feature".into(), "bar".into())
+                .key_value("opt".into(), "42".into())
+            ),
+        },
+    );
+
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮Bar: _
+        ⋮Baz: t v
+        ⋮Foo: t v
+    "###);
+}

crates/ra_hir/src/ty/tests.rs

@@ -3,6 +3,7 @@ use std::sync::Arc;
 
 use insta::assert_snapshot;
 
+use ra_cfg::CfgOptions;
 use ra_db::{salsa::Database, FilePosition, SourceDatabase};
 use ra_syntax::{
     algo,
@@ -23,6 +24,50 @@ use crate::{
 mod never_type;
 mod coercion;
 
+#[test]
+fn cfg_impl_block() {
+    let (mut db, pos) = MockDatabase::with_position(
+        r#"
+//- /main.rs
+use foo::S as T;
+struct S;
+
+#[cfg(test)]
+impl S {
+    fn foo1(&self) -> i32 { 0 }
+}
+
+#[cfg(not(test))]
+impl S {
+    fn foo2(&self) -> i32 { 0 }
+}
+
+fn test() {
+    let t = (S.foo1(), S.foo2(), T.foo3(), T.foo4());
+    t<|>;
+}
+
+//- /foo.rs
+struct S;
+
+#[cfg(not(test))]
+impl S {
+    fn foo3(&self) -> i32 { 0 }
+}
+
+#[cfg(test)]
+impl S {
+    fn foo4(&self) -> i32 { 0 }
+}
+"#,
+    );
+    db.set_crate_graph_from_fixture(crate_graph! {
+        "main": ("/main.rs", ["foo"], CfgOptions::default().atom("test".into())),
+        "foo": ("/foo.rs", []),
+    });
+    assert_eq!("(i32, {unknown}, i32, {unknown})", type_at_pos(&db, pos));
+}
+
 #[test]
 fn infer_await() {
     let (mut db, pos) = MockDatabase::with_position(