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 <[email protected]>
Co-authored-by: oxalica <[email protected]>

3 files changed, 150 insertions, 27 deletions

diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index a568fdabd..cef2dc9d2 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/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()
diff --git a/crates/ra_hir/src/nameres/raw.rs b/crates/ra_hir/src/nameres/raw.rs
index 606bd1a95..623b343c4 100644
--- a/crates/ra_hir/src/nameres/raw.rs
+++ b/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)
     }
 }
 
diff --git a/crates/ra_hir/src/nameres/tests.rs b/crates/ra_hir/src/nameres/tests.rs
index bc4b47b70..34dd79574 100644
--- a/crates/ra_hir/src/nameres/tests.rs
+++ b/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
+    "###);
+}