Merge #1267

1267: Macro expand to r=edwin0cheng a=matklad

closes #1264 

The core problem this PR is trying to wrangle is that macros can expand to different stuffs, depending on context. 

That is, `foo!()` on the top-level expands to a list of items, but the same `foo!()` in expression position expands to expression.

Our current `hir_parse(HirFileId) -> TreeArc<SourceFile>` does not really support this. 

So, the plan is to change `hir_parse` to untyped inreface (`TreeArc<Syntaxnode>`), and add `expands_to` field to `MacroCallLoc`, such that the *target* of macro expansion is selected by the calling code and is part of macro id. 

This unfortunately looses some type-safety :( 


Moreover, this doesn't really fix #1264 by itself, because we die due to some other error inside macro expansion: expander fails to produce a tree with a single root, which trips assert inside rowan.

Co-authored-by: Aleksey Kladov <[email protected]>

2 files changed, 7 insertions, 4 deletions

diff --git a/crates/ra_hir/src/nameres/collector.rs b/crates/ra_hir/src/nameres/collector.rs
index 4640b3b74..c615d80c3 100644
--- a/crates/ra_hir/src/nameres/collector.rs
+++ b/crates/ra_hir/src/nameres/collector.rs
@@ -15,7 +15,7 @@ use crate::{
         diagnostics::DefDiagnostic,
         raw,
     },
-    ids::{AstItemDef, LocationCtx, MacroCallLoc, MacroCallId, MacroDefId},
+    ids::{AstItemDef, LocationCtx, MacroCallLoc, MacroCallId, MacroDefId, MacroFileKind},
     AstId,
 };
 
@@ -371,7 +371,7 @@ where
         self.macro_stack_monitor.increase(macro_def_id);
 
         if !self.macro_stack_monitor.is_poison(macro_def_id) {
-            let file_id: HirFileId = macro_call_id.into();
+            let file_id: HirFileId = macro_call_id.as_file(MacroFileKind::Items);
             let raw_items = self.db.raw_items(file_id);
             ModCollector { def_collector: &mut *self, file_id, module_id, raw_items: &raw_items }
                 .collect(raw_items.items());
diff --git a/crates/ra_hir/src/nameres/raw.rs b/crates/ra_hir/src/nameres/raw.rs
index 211e02068..bd32b264b 100644
--- a/crates/ra_hir/src/nameres/raw.rs
+++ b/crates/ra_hir/src/nameres/raw.rs
@@ -75,8 +75,11 @@ impl RawItems {
             source_ast_id_map: db.ast_id_map(file_id.into()),
             source_map: ImportSourceMap::default(),
         };
-        let source_file = db.hir_parse(file_id);
-        collector.process_module(None, &*source_file);
+        if let Some(node) = db.parse_or_expand(file_id) {
+            if let Some(source_file) = ast::SourceFile::cast(&node) {
+                collector.process_module(None, &*source_file);
+            }
+        }
         (Arc::new(collector.raw_items), Arc::new(collector.source_map))
     }