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]>

1 files changed, 3 insertions, 3 deletions

diff --git a/crates/ra_hir/src/diagnostics.rs b/crates/ra_hir/src/diagnostics.rs
index d41525779..4b7b2dbee 100644
--- a/crates/ra_hir/src/diagnostics.rs
+++ b/crates/ra_hir/src/diagnostics.rs
@@ -1,6 +1,6 @@
 use std::{fmt, any::Any};
 
-use ra_syntax::{SyntaxNodePtr, TreeArc, AstPtr, TextRange, ast, SyntaxNode, AstNode};
+use ra_syntax::{SyntaxNodePtr, TreeArc, AstPtr, TextRange, ast, SyntaxNode};
 use relative_path::RelativePathBuf;
 
 use crate::{HirFileId, HirDatabase, Name};
@@ -29,8 +29,8 @@ pub trait Diagnostic: Any + Send + Sync + fmt::Debug + 'static {
 
 impl dyn Diagnostic {
     pub fn syntax_node(&self, db: &impl HirDatabase) -> TreeArc<SyntaxNode> {
-        let source_file = db.hir_parse(self.file());
-        self.syntax_node_ptr().to_node(source_file.syntax()).to_owned()
+        let node = db.parse_or_expand(self.file()).unwrap();
+        self.syntax_node_ptr().to_node(&*node).to_owned()
     }
     pub fn downcast_ref<D: Diagnostic>(&self) -> Option<&D> {
         self.as_any().downcast_ref()