add pre-requisite for calling into compiler API (#663)

2020-04-04 09:37:39 +02:00 · 2020-04-04 09:37:39 +02:00 · e93f50cf0d
commit e93f50cf0d
parent 62ef95760a
1 changed files with 4 additions and 0 deletions
--- a/src/doc/rustc-dev-guide/src/rustc-driver-interacting-with-the-ast.md
+++ b/src/doc/rustc-dev-guide/src/rustc-driver-interacting-with-the-ast.md
@ -4,6 +4,10 @@

 ## Getting the type of an expression

+NOTE: For the example to compile, you will need to first run the following:
+
+    rustup component add rustc-dev
+
 To get the type of an expression, use the `global_ctxt` to get a `TyCtxt`:

 ```rust