Make it opt-in

crates/rust-analyzer/src/config.rs

@@ -126,6 +126,9 @@ config_data! {
         /// and a blue icon in the `Problems Panel`.
         diagnostics_warningsAsInfo: Vec<String> = "[]",
 
+        /// Expand attribute macros.
+        experimental_procAttrMacros: bool = "false",
+
         /// Controls file watching implementation.
         files_watcher: String = "\"client\"",
         /// These directories will be ignored by rust-analyzer.
@@ -546,6 +549,9 @@ impl Config {
         let path = self.data.procMacro_server.clone().or_else(|| std::env::current_exe().ok())?;
         Some((path, vec!["proc-macro".into()]))
     }
+    pub fn expand_proc_attr_macros(&self) -> bool {
+        self.data.experimental_procAttrMacros
+    }
     pub fn files(&self) -> FilesConfig {
         FilesConfig {
             watcher: match self.data.files_watcher.as_str() {

crates/rust-analyzer/src/global_state.rs

@@ -119,12 +119,12 @@ impl GlobalState {
 
         let analysis_host = AnalysisHost::new(config.lru_capacity());
         let (flycheck_sender, flycheck_receiver) = unbounded();
-        GlobalState {
+        let mut this = GlobalState {
             sender,
             req_queue: ReqQueue::default(),
             task_pool,
             loader,
-            config: Arc::new(config),
+            config: Arc::new(config.clone()),
             analysis_host,
             diagnostics: Default::default(),
             mem_docs: FxHashMap::default(),
@@ -151,7 +151,10 @@ impl GlobalState {
 
             fetch_build_data_queue: OpQueue::default(),
             latest_requests: Default::default(),
-        }
+        };
+        // Apply any required database inputs from the config.
+        this.update_configuration(config);
+        this
     }
 
     pub(crate) fn process_changes(&mut self) -> bool {

crates/rust-analyzer/src/reload.rs

@@ -2,6 +2,7 @@
 use std::{mem, sync::Arc};
 
 use flycheck::{FlycheckConfig, FlycheckHandle};
+use hir::db::DefDatabase;
 use ide::Change;
 use ide_db::base_db::{CrateGraph, SourceRoot, VfsPath};
 use project_model::{BuildDataCollector, BuildDataResult, ProcMacroClient, ProjectWorkspace};
@@ -47,6 +48,11 @@ impl GlobalState {
         } else if self.config.flycheck() != old_config.flycheck() {
             self.reload_flycheck();
         }
+
+        // Apply experimental feature flags.
+        self.analysis_host
+            .raw_database_mut()
+            .set_enable_proc_attr_macros(self.config.expand_proc_attr_macros());
     }
     pub(crate) fn maybe_refresh(&mut self, changes: &[(AbsPathBuf, ChangeKind)]) {
         if !changes.iter().any(|(path, kind)| is_interesting(path, *kind)) {