Merge #8997

8997: internal: stop expanding UseTrees during ItemTree lowering r=jonas-schievink a=jonas-schievink

Closes https://github.com/rust-analyzer/rust-analyzer/issues/8908

Messy diff, but `ItemTree` lowering got simpler, since we now have a strict 1-to-1 mapping between `ast::Item` and `ModItem`.

The most messy part is mapping a single `UseTree` back to its `ast::UseTree` counterpart for diagnostics, but I think the ad-hoc source map built during lowering does the job.

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

1 files changed, 5 insertions, 3 deletions

diff --git a/crates/hir_def/src/test_db.rs b/crates/hir_def/src/test_db.rs
index 6c357c915..a9c1e13e2 100644
--- a/crates/hir_def/src/test_db.rs
+++ b/crates/hir_def/src/test_db.rs
@@ -278,9 +278,11 @@ impl TestDB {
                         let node = ast.to_node(self.upcast());
                         (InFile::new(ast.file_id, node.syntax().clone()), "UnresolvedExternCrate")
                     }
-                    DefDiagnosticKind::UnresolvedImport { ast, .. } => {
-                        let node = ast.to_node(self.upcast());
-                        (InFile::new(ast.file_id, node.syntax().clone()), "UnresolvedImport")
+                    DefDiagnosticKind::UnresolvedImport { id, .. } => {
+                        let item_tree = id.item_tree(self.upcast());
+                        let import = &item_tree[id.value];
+                        let node = InFile::new(id.file_id(), import.ast_id).to_node(self.upcast());
+                        (InFile::new(id.file_id(), node.syntax().clone()), "UnresolvedImport")
                     }
                     DefDiagnosticKind::UnconfiguredCode { ast, .. } => {
                         let node = ast.to_node(self.upcast());