fix: server: go to type definition

src/Lean/Server/FileWorker.lean

@@ -414,7 +414,10 @@ section RequestHandling
       (notFoundX := pure #[]) fun snap => do
         for t in snap.toCmdState.infoState.trees do
           if let some (ci, Info.ofTermInfo i) := t.hoverableInfoAt? hoverPos then
-            let expr ← if goToType? then ci.runMetaM i.lctx <| Meta.inferType i.expr else i.expr
+            let mut expr := i.expr
+            if goToType? then
+              expr ← ci.runMetaM i.lctx do
+                Meta.instantiateMVars (← Meta.inferType expr)
             if let some n := expr.constName? then
               let mod? ← ci.runMetaM i.lctx <| findModuleOf? n
               let modUri? ← match mod? with

tests/lean/interactive/definition.lean

@@ -0,0 +1,6 @@
+inductive Foo where
+  | foo
+example : Foo :=
+  let c := Foo.foo
+  c
+--^ textDocument/typeDefinition

tests/lean/interactive/definition.lean.expected.out

@@ -0,0 +1,9 @@
+{"textDocument": {"uri": "file://definition.lean"},
+ "position": {"line": 4, "character": 2}}
+[{"targetUri": "file://definition.lean",
+  "targetSelectionRange":
+  {"start": {"line": 0, "character": 10}, "end": {"line": 0, "character": 13}},
+  "targetRange":
+  {"start": {"line": 0, "character": 0}, "end": {"line": 1, "character": 7}},
+  "originSelectionRange":
+  {"start": {"line": 4, "character": 2}, "end": {"line": 4, "character": 3}}}]