Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir_expand/src/builtin_attr_macro.rs')
| -rw-r--r-- | crates/hir_expand/src/builtin_attr_macro.rs | 79 |
1 files changed, 77 insertions, 2 deletions
diff --git a/crates/hir_expand/src/builtin_attr_macro.rs b/crates/hir_expand/src/builtin_attr_macro.rs index 907ee02e33..1996624598 100644 --- a/crates/hir_expand/src/builtin_attr_macro.rs +++ b/crates/hir_expand/src/builtin_attr_macro.rs @@ -1,9 +1,11 @@ //! Builtin attributes. +use itertools::Itertools; use syntax::ast; use crate::{ - db::AstDatabase, name, AstId, CrateId, ExpandResult, MacroCallId, MacroDefId, MacroDefKind, + db::AstDatabase, name, AstId, CrateId, ExpandResult, MacroCallId, MacroCallKind, MacroDefId, + MacroDefKind, }; macro_rules! register_builtin { @@ -53,7 +55,7 @@ register_builtin! { (bench, Bench) => dummy_attr_expand, (cfg_accessible, CfgAccessible) => dummy_attr_expand, (cfg_eval, CfgEval) => dummy_attr_expand, - (derive, Derive) => dummy_attr_expand, + (derive, Derive) => derive_attr_expand, (global_allocator, GlobalAllocator) => dummy_attr_expand, (test, Test) => dummy_attr_expand, (test_case, TestCase) => dummy_attr_expand @@ -79,3 +81,76 @@ fn dummy_attr_expand( ) -> ExpandResult<tt::Subtree> { ExpandResult::ok(tt.clone()) } + +fn derive_attr_expand( + db: &dyn AstDatabase, + id: MacroCallId, + tt: &tt::Subtree, +) -> ExpandResult<tt::Subtree> { + // we generate a very specific expansion here, as we do not actually expand the `#[derive]` attribute + // itself in name res, but we do want to expand it to something for the IDE layer, so that the input + // derive attributes can be downmapped, and resolved + // This is basically a hack, to get rid of hacks in the IDE layer that slowly accumulate more and more + // in various places. + + // we transform the token tree of `#[derive(Foo, bar::Bar)]` into + // ``` + // #[Foo] + // #[bar::Bar] + // (); + // ``` + // which allows fallback path resolution in hir::Semantics to properly identify our derives + let loc = db.lookup_intern_macro_call(id); + let derives = match &loc.kind { + MacroCallKind::Attr { attr_args, .. } => &attr_args.0, + _ => return ExpandResult::ok(tt.clone()), + }; + + let mut token_trees = Vec::new(); + for (comma, group) in &derives + .token_trees + .iter() + .filter_map(|tt| match tt { + tt::TokenTree::Leaf(l) => Some(l), + tt::TokenTree::Subtree(_) => None, + }) + .group_by(|l| matches!(l, tt::Leaf::Punct(tt::Punct { char: ',', .. }))) + { + if comma { + continue; + } + let wrap = |leaf| tt::TokenTree::Leaf(tt::Leaf::Punct(leaf)); + token_trees.push(wrap(tt::Punct { + char: '#', + spacing: tt::Spacing::Alone, + id: tt::TokenId::unspecified(), + })); + token_trees.push(wrap(tt::Punct { + char: '[', + spacing: tt::Spacing::Alone, + id: tt::TokenId::unspecified(), + })); + token_trees.extend(group.cloned().map(tt::TokenTree::Leaf)); + token_trees.push(wrap(tt::Punct { + char: ']', + spacing: tt::Spacing::Alone, + id: tt::TokenId::unspecified(), + })); + token_trees.push(wrap(tt::Punct { + char: '(', + spacing: tt::Spacing::Alone, + id: tt::TokenId::unspecified(), + })); + token_trees.push(wrap(tt::Punct { + char: ')', + spacing: tt::Spacing::Alone, + id: tt::TokenId::unspecified(), + })); + token_trees.push(wrap(tt::Punct { + char: ';', + spacing: tt::Spacing::Alone, + id: tt::TokenId::unspecified(), + })); + } + ExpandResult::ok(tt::Subtree { delimiter: tt.delimiter, token_trees }) +} |