Merge #8916

8916: ItemTree pretty-printing r=jonas-schievink a=jonas-schievink

This adds a printer for `ItemTree` contents, and a few tests to ensure that `ItemTree` lowering works like we expect it to. It also adds a new "Debug ItemTree" command that can be used to see the `ItemTree` of the currently open file. The pretty-printed output is usually close enough to Rust syntax that we can even use Rust syntax highlighting.

This is similar to the old `ItemTree` tests we had, but produces significantly more readable output, so these should actually carry their weight.

Co-authored-by: Jonas Schievink <[email protected]>

1 files changed, 10 insertions, 1 deletions

diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index aadd4e44a..89a1ea770 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -2,7 +2,7 @@
 
 use std::{
     convert::{TryFrom, TryInto},
-    ops,
+    fmt, ops,
     sync::Arc,
 };
 
@@ -648,6 +648,15 @@ pub enum AttrInput {
     TokenTree(Subtree),
 }
 
+impl fmt::Display for AttrInput {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            AttrInput::Literal(lit) => write!(f, " = \"{}\"", lit.escape_debug()),
+            AttrInput::TokenTree(subtree) => subtree.fmt(f),
+        }
+    }
+}
+
 impl Attr {
     fn from_src(
         db: &dyn DefDatabase,