2 files changed, 33 insertions, 6 deletions

diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index 386287518..19cd713ba 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -7,7 +7,6 @@ use std::iter;
 
 use base_db::{CrateId, FileId, ProcMacroId};
 use cfg::{CfgExpr, CfgOptions};
-use hir_expand::InFile;
 use hir_expand::{
     ast_id_map::FileAstId,
     builtin_derive::find_builtin_derive,
@@ -16,6 +15,7 @@ use hir_expand::{
     proc_macro::ProcMacroExpander,
     HirFileId, MacroCallId, MacroDefId, MacroDefKind,
 };
+use hir_expand::{InFile, MacroCallLoc};
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::ast;
 use test_utils::mark;
@@ -812,7 +812,30 @@ impl DefCollector<'_> {
             log::warn!("macro expansion is too deep");
             return;
         }
-        let file_id: HirFileId = macro_call_id.as_file();
+        let file_id = macro_call_id.as_file();
+
+        // First, fetch the raw expansion result for purposes of error reporting. This goes through
+        // `macro_expand_error` to avoid depending on the full expansion result (to improve
+        // incrementality).
+        let err = self.db.macro_expand_error(macro_call_id);
+        if let Some(err) = err {
+            if let MacroCallId::LazyMacro(id) = macro_call_id {
+                let loc: MacroCallLoc = self.db.lookup_intern_macro(id);
+
+                let diag = match err {
+                    hir_expand::ExpandError::UnresolvedProcMacro => {
+                        // Missing proc macros are non-fatal, so they are handled specially.
+                        DefDiagnostic::unresolved_proc_macro(module_id, loc.kind)
+                    }
+                    _ => DefDiagnostic::macro_error(module_id, loc.kind, err.to_string()),
+                };
+
+                self.def_map.diagnostics.push(diag);
+            }
+            // FIXME: Handle eager macros.
+        }
+
+        // Then, fetch and process the item tree. This will reuse the expansion result from above.
         let item_tree = self.db.item_tree(file_id);
         let mod_dir = self.mod_dirs[&module_id].clone();
         ModCollector {
@@ -1336,13 +1359,11 @@ impl ModCollector<'_, '_> {
 
     fn emit_unconfigured_diagnostic(&mut self, item: ModItem, cfg: &CfgExpr) {
         let ast_id = item.ast_id(self.item_tree);
-        let id_map = self.def_collector.db.ast_id_map(self.file_id);
-        let syntax_ptr = id_map.get(ast_id).syntax_node_ptr();
 
-        let ast_node = InFile::new(self.file_id, syntax_ptr);
+        let ast_id = InFile::new(self.file_id, ast_id);
         self.def_collector.def_map.diagnostics.push(DefDiagnostic::unconfigured_code(
             self.module_id,
-            ast_node,
+            ast_id,
             cfg.clone(),
             self.def_collector.cfg_options.clone(),
         ));
diff --git a/crates/hir_def/src/nameres/tests/incremental.rs b/crates/hir_def/src/nameres/tests/incremental.rs
index cfbc62cc4..8981fa7c9 100644
--- a/crates/hir_def/src/nameres/tests/incremental.rs
+++ b/crates/hir_def/src/nameres/tests/incremental.rs
@@ -38,6 +38,9 @@ fn typing_inside_a_function_should_not_invalidate_def_map() {
         fn foo() -> i32 {
             1 + 1
         }
+
+        #[cfg(never)]
+        fn no() {}
         //- /foo/mod.rs
         pub mod bar;
 
@@ -53,6 +56,9 @@ fn typing_inside_a_function_should_not_invalidate_def_map() {
         use E::*;
 
         fn foo() -> i32 { 92 }
+
+        #[cfg(never)]
+        fn no() {}
         ",
     );
 }