Merge #9128

9128: feat: expand procedural attribute macros r=jonas-schievink a=jonas-schievink

This adds experimental support for attribute macros. They can be enabled by setting `rust-analyzer.experimental.procAttrMacros` to `true`.

Known issues:
* Tokens aren't remapped, presumably because we edit the input syntax tree (this causes IDE features to not work inside items with attribute macros on them)
* Macro errors aren't reported correctly

Closes https://github.com/rust-analyzer/rust-analyzer/issues/8971
Fixes https://github.com/rust-analyzer/rust-analyzer/issues/8964 / https://github.com/la10736/rstest/issues/120
Fixes https://github.com/rust-analyzer/rust-analyzer/issues/2984
Fixes https://github.com/rust-analyzer/rust-analyzer/issues/5412
Fixes https://github.com/rust-analyzer/rust-analyzer/issues/6029
Fixes https://github.com/rust-analyzer/rust-analyzer/issues/6687

https://github.com/rust-analyzer/rust-analyzer/issues/6740 is still not fixed – we now expand `#[proc_macro_hack]`, but fail to expand the resulting `proc_macro_call!()` macro.

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

1 files changed, 19 insertions, 0 deletions

diff --git a/crates/hir_expand/src/input.rs b/crates/hir_expand/src/input.rs
index fe4790e7b..40116a479 100644
--- a/crates/hir_expand/src/input.rs
+++ b/crates/hir_expand/src/input.rs
@@ -28,6 +28,14 @@ pub(crate) fn process_macro_input(
 
             remove_derives_up_to(item, derive_attr_index as usize).syntax().clone()
         }
+        MacroCallKind::Attr { invoc_attr_index, .. } => {
+            let item = match ast::Item::cast(node.clone()) {
+                Some(item) => item,
+                None => return node,
+            };
+
+            remove_attr_invoc(item, invoc_attr_index as usize).syntax().clone()
+        }
     }
 }
 
@@ -46,6 +54,17 @@ fn remove_derives_up_to(item: ast::Item, attr_index: usize) -> ast::Item {
     item
 }
 
+/// Removes the attribute invoking an attribute macro from `item`.
+fn remove_attr_invoc(item: ast::Item, attr_index: usize) -> ast::Item {
+    let item = item.clone_for_update();
+    let attr = item
+        .attrs()
+        .nth(attr_index)
+        .unwrap_or_else(|| panic!("cannot find attribute #{}", attr_index));
+    attr.syntax().detach();
+    item
+}
+
 #[cfg(test)]
 mod tests {
     use base_db::fixture::WithFixture;