Merge #2169

2169: MBE: Mapping spans for goto definition r=matklad a=edwin0cheng

Currently, go to definition gives the wrong span in MBE.  This PR implement a mapping mechanism to fix it and it could be used for future MBE hygiene implementation.

The basic idea of the mapping is:
1. When expanding the macro, generated 2 `TokenMap` which maps the macro args and macro defs between tokens and input text-ranges.
2. Before converting generated `TokenTree` to `SyntaxNode`, generated a `ExpandedRangeMap` which is a mapping between token and output text-ranges.
3. Using these 3 mappings to construct an `ExpansionInfo`  which can map between input text ranges and output text ranges.


Co-authored-by: Edwin Cheng <[email protected]>

1 files changed, 5 insertions, 1 deletions

diff --git a/crates/ra_mbe/src/lib.rs b/crates/ra_mbe/src/lib.rs
index 15f000175..70a289f09 100644
--- a/crates/ra_mbe/src/lib.rs
+++ b/crates/ra_mbe/src/lib.rs
@@ -32,7 +32,7 @@ pub enum ExpandError {
 
 pub use crate::syntax_bridge::{
     ast_to_token_tree, syntax_node_to_token_tree, token_tree_to_expr, token_tree_to_items,
-    token_tree_to_macro_stmts, token_tree_to_pat, token_tree_to_ty,
+    token_tree_to_macro_stmts, token_tree_to_pat, token_tree_to_ty, RevTokenMap, TokenMap,
 };
 
 /// This struct contains AST for a single `macro_rules` definition. What might
@@ -118,6 +118,10 @@ impl MacroRules {
         shift_subtree(&mut tt, self.shift);
         mbe_expander::expand(self, &tt)
     }
+
+    pub fn shift(&self) -> u32 {
+        self.shift
+    }
 }
 
 impl Rule {