Expand into pseudo-derive attribute expansions in completions

crates/hir/src/semantics.rs

@@ -151,6 +151,10 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.expand_attr_macro(item)
     }
 
+    pub fn expand_derive_as_pseudo_attr_macro(&self, attr: &ast::Attr) -> Option<SyntaxNode> {
+        self.imp.expand_derive_as_pseudo_attr_macro(attr)
+    }
+
     pub fn resolve_derive_macro(&self, derive: &ast::Attr) -> Option<Vec<Option<Macro>>> {
         self.imp.resolve_derive_macro(derive)
     }
@@ -185,6 +189,19 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.speculative_expand_attr(actual_macro_call, speculative_args, token_to_map)
     }
 
+    pub fn speculative_expand_derive_as_pseudo_attr_macro(
+        &self,
+        actual_macro_call: &ast::Attr,
+        speculative_args: &ast::Attr,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        self.imp.speculative_expand_derive_as_pseudo_attr_macro(
+            actual_macro_call,
+            speculative_args,
+            token_to_map,
+        )
+    }
+
     /// Descend the token into macrocalls to its first mapped counterpart.
     pub fn descend_into_macros_single(&self, token: SyntaxToken) -> SyntaxToken {
         self.imp.descend_into_macros_single(token)
@@ -438,9 +455,16 @@ impl<'db> SemanticsImpl<'db> {
     fn expand_attr_macro(&self, item: &ast::Item) -> Option<SyntaxNode> {
         let src = self.wrap_node_infile(item.clone());
         let macro_call_id = self.with_ctx(|ctx| ctx.item_to_macro_call(src))?;
-        let file_id = macro_call_id.as_file();
+        self.parse_or_expand(macro_call_id.as_file())
-        let node = self.parse_or_expand(file_id)?;
+    }
-        Some(node)
+
+    fn expand_derive_as_pseudo_attr_macro(&self, attr: &ast::Attr) -> Option<SyntaxNode> {
+        let src = self.wrap_node_infile(attr.clone());
+        let adt = attr.syntax().parent().and_then(ast::Adt::cast)?;
+        let call_id = self.with_ctx(|ctx| {
+            ctx.attr_to_derive_macro_call(src.with_value(&adt), src).map(|(_, it, _)| it)
+        })?;
+        self.parse_or_expand(call_id.as_file())
     }
 
     fn resolve_derive_macro(&self, attr: &ast::Attr) -> Option<Vec<Option<Macro>>> {
@@ -533,6 +557,25 @@ impl<'db> SemanticsImpl<'db> {
         )
     }
 
+    fn speculative_expand_derive_as_pseudo_attr_macro(
+        &self,
+        actual_macro_call: &ast::Attr,
+        speculative_args: &ast::Attr,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        let attr = self.wrap_node_infile(actual_macro_call.clone());
+        let adt = actual_macro_call.syntax().parent().and_then(ast::Adt::cast)?;
+        let macro_call_id = self.with_ctx(|ctx| {
+            ctx.attr_to_derive_macro_call(attr.with_value(&adt), attr).map(|(_, it, _)| it)
+        })?;
+        hir_expand::db::expand_speculative(
+            self.db.upcast(),
+            macro_call_id,
+            speculative_args.syntax(),
+            token_to_map,
+        )
+    }
+
     // This might not be the correct way to do this, but it works for now
     fn descend_node_into_attributes<N: AstNode>(&self, node: N) -> SmallVec<[N; 1]> {
         let mut res = smallvec![];

crates/hir_expand/src/builtin_attr_macro.rs

@@ -1,7 +1,5 @@
 //! Builtin attributes.
 
-use itertools::Itertools;
-
 use crate::{db::AstDatabase, name, ExpandResult, MacroCallId, MacroCallKind};
 
 macro_rules! register_builtin {
@@ -98,10 +96,16 @@ fn derive_attr_expand(
 ) -> ExpandResult<tt::Subtree> {
     let loc = db.lookup_intern_macro_call(id);
     let derives = match &loc.kind {
-        MacroCallKind::Attr { attr_args, .. } => &attr_args.0,
+        MacroCallKind::Attr { attr_args, is_derive: true, .. } => &attr_args.0,
-        _ => return ExpandResult::ok(tt.clone()),
+        _ => return ExpandResult::ok(Default::default()),
     };
+    pseudo_derive_attr_expansion(tt, derives)
+}
 
+pub fn pseudo_derive_attr_expansion(
+    tt: &tt::Subtree,
+    args: &tt::Subtree,
+) -> ExpandResult<tt::Subtree> {
     let mk_leaf = |char| {
         tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct {
             char,
@@ -111,21 +115,12 @@ fn derive_attr_expand(
     };
 
     let mut token_trees = Vec::new();
-    for (comma, group) in &derives
+    for tt in (&args.token_trees)
-        .token_trees
+        .split(|tt| matches!(tt, tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: ',', .. }))))
-        .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;
-        }
         token_trees.push(mk_leaf('#'));
         token_trees.push(mk_leaf('['));
-        token_trees.extend(group.cloned().map(tt::TokenTree::Leaf));
+        token_trees.extend(tt.iter().cloned());
         token_trees.push(mk_leaf(']'));
     }
     token_trees.push(mk_leaf('('));

crates/hir_expand/src/db.rs

@@ -14,10 +14,10 @@ use syntax::{
 };
 
 use crate::{
-    ast_id_map::AstIdMap, fixup, hygiene::HygieneFrame, BuiltinAttrExpander, BuiltinDeriveExpander,
+    ast_id_map::AstIdMap, builtin_attr_macro::pseudo_derive_attr_expansion, fixup,
-    BuiltinFnLikeExpander, ExpandError, ExpandResult, ExpandTo, HirFileId, HirFileIdRepr,
+    hygiene::HygieneFrame, BuiltinAttrExpander, BuiltinDeriveExpander, BuiltinFnLikeExpander,
-    MacroCallId, MacroCallKind, MacroCallLoc, MacroDefId, MacroDefKind, MacroFile,
+    ExpandError, ExpandResult, ExpandTo, HirFileId, HirFileIdRepr, MacroCallId, MacroCallKind,
-    ProcMacroExpander,
+    MacroCallLoc, MacroDefId, MacroDefKind, MacroFile, ProcMacroExpander,
 };
 
 /// Total limit on the number of tokens produced by any macro invocation.
@@ -161,14 +161,16 @@ pub fn expand_speculative(
     );
 
     let (attr_arg, token_id) = match loc.kind {
-        MacroCallKind::Attr { invoc_attr_index, .. } => {
+        MacroCallKind::Attr { invoc_attr_index, is_derive, .. } => {
-            // Attributes may have an input token tree, build the subtree and map for this as well
+            let attr = if is_derive {
-            // then try finding a token id for our token if it is inside this input subtree.
+                // for pseudo-derive expansion we actually pass the attribute itself only
-            let item = ast::Item::cast(speculative_args.clone())?;
+                ast::Attr::cast(speculative_args.clone())
-            let attr = item
+            } else {
-                .doc_comments_and_attrs()
+                // Attributes may have an input token tree, build the subtree and map for this as well
-                .nth(invoc_attr_index as usize)
+                // then try finding a token id for our token if it is inside this input subtree.
-                .and_then(Either::left)?;
+                let item = ast::Item::cast(speculative_args.clone())?;
+                item.doc_comments_and_attrs().nth(invoc_attr_index as usize).and_then(Either::left)
+            }?;
             match attr.token_tree() {
                 Some(token_tree) => {
                     let (mut tree, map) = syntax_node_to_token_tree(attr.token_tree()?.syntax());
@@ -205,11 +207,15 @@ pub fn expand_speculative(
 
     // Do the actual expansion, we need to directly expand the proc macro due to the attribute args
     // Otherwise the expand query will fetch the non speculative attribute args and pass those instead.
-    let mut speculative_expansion = if let MacroDefKind::ProcMacro(expander, ..) = loc.def.kind {
+    let mut speculative_expansion = match loc.def.kind {
-        tt.delimiter = None;
+        MacroDefKind::ProcMacro(expander, ..) => {
-        expander.expand(db, loc.krate, &tt, attr_arg.as_ref())
+            tt.delimiter = None;
-    } else {
+            expander.expand(db, loc.krate, &tt, attr_arg.as_ref())
-        macro_def.expand(db, actual_macro_call, &tt)
+        }
+        MacroDefKind::BuiltInAttr(BuiltinAttrExpander::Derive, _) => {
+            pseudo_derive_attr_expansion(&tt, attr_arg.as_ref()?)
+        }
+        _ => macro_def.expand(db, actual_macro_call, &tt),
     };
 
     let expand_to = macro_expand_to(db, actual_macro_call);

crates/ide_assists/src/handlers/remove_dbg.rs

@@ -32,7 +32,7 @@ pub(crate) fn remove_dbg(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     }
 
     let mac_input = tt.syntax().children_with_tokens().skip(1).take_while(|it| *it != r_delim);
-    let input_expressions = mac_input.into_iter().group_by(|tok| tok.kind() == T![,]);
+    let input_expressions = mac_input.group_by(|tok| tok.kind() == T![,]);
     let input_expressions = input_expressions
         .into_iter()
         .filter_map(|(is_sep, group)| (!is_sep).then(|| group))

crates/ide_completion/src/completions/attribute.rs

@@ -29,6 +29,8 @@ mod derive;
 mod lint;
 mod repr;
 
+pub(crate) use self::derive::complete_derive;
+
 /// Complete inputs to known builtin attributes as well as derive attributes
 pub(crate) fn complete_known_attribute_input(
     acc: &mut Completions,
@@ -46,7 +48,6 @@ pub(crate) fn complete_known_attribute_input(
 
     match path.text().as_str() {
         "repr" => repr::complete_repr(acc, ctx, tt),
-        "derive" => derive::complete_derive(acc, ctx, ctx.attr.as_ref()?),
         "feature" => lint::complete_lint(acc, ctx, &parse_tt_as_comma_sep_paths(tt)?, FEATURES),
         "allow" | "warn" | "deny" | "forbid" => {
             let existing_lints = parse_tt_as_comma_sep_paths(tt)?;
@@ -62,9 +63,7 @@ pub(crate) fn complete_known_attribute_input(
 
             lint::complete_lint(acc, ctx, &existing_lints, &lints);
         }
-        "cfg" => {
+        "cfg" => cfg::complete_cfg(acc, ctx),
-            cfg::complete_cfg(acc, ctx);
-        }
         _ => (),
     }
     Some(())
@@ -347,7 +346,7 @@ fn parse_comma_sep_expr(input: ast::TokenTree) -> Option<Vec<ast::Expr>> {
         .children_with_tokens()
         .skip(1)
         .take_while(|it| it.as_token() != Some(&r_paren));
-    let input_expressions = tokens.into_iter().group_by(|tok| tok.kind() == T![,]);
+    let input_expressions = tokens.group_by(|tok| tok.kind() == T![,]);
     Some(
         input_expressions
             .into_iter()

crates/ide_completion/src/completions/attribute/derive.rs

@@ -6,14 +6,21 @@ use ide_db::{
 };
 use itertools::Itertools;
 use rustc_hash::FxHashSet;
-use syntax::{ast, SmolStr, SyntaxKind};
+use syntax::{SmolStr, SyntaxKind};
 
 use crate::{
-    completions::flyimport::compute_fuzzy_completion_order_key, context::CompletionContext,
+    completions::flyimport::compute_fuzzy_completion_order_key,
-    item::CompletionItem, Completions, ImportEdit,
+    context::{CompletionContext, PathCompletionCtx, PathKind},
+    item::CompletionItem,
+    Completions, ImportEdit,
 };
 
-pub(super) fn complete_derive(acc: &mut Completions, ctx: &CompletionContext, attr: &ast::Attr) {
+pub(crate) fn complete_derive(acc: &mut Completions, ctx: &CompletionContext) {
+    let attr = match (&ctx.path_context, ctx.attr.as_ref()) {
+        (Some(PathCompletionCtx { kind: Some(PathKind::Derive), .. }), Some(attr)) => attr,
+        _ => return,
+    };
+
     let core = ctx.famous_defs().core();
     let existing_derives: FxHashSet<_> =
         ctx.sema.resolve_derive_macro(attr).into_iter().flatten().flatten().collect();

crates/ide_completion/src/completions/flyimport.rs

@@ -153,7 +153,7 @@ pub(crate) fn import_on_the_fly(acc: &mut Completions, ctx: &CompletionContext)
         };
         match (kind, import.original_item) {
             // Aren't handled in flyimport
-            (PathKind::Vis { .. } | PathKind::Use, _) => false,
+            (PathKind::Vis { .. } | PathKind::Use | PathKind::Derive, _) => false,
             // modules are always fair game
             (_, ItemInNs::Types(hir::ModuleDef::Module(_))) => true,
             // and so are macros(except for attributes)

crates/ide_completion/src/completions/qualified_path.rs

@@ -63,7 +63,13 @@ pub(crate) fn complete_qualified_path(acc: &mut Completions, ctx: &CompletionCon
     }
 
     match kind {
-        Some(PathKind::Pat | PathKind::Attr { .. } | PathKind::Vis { .. } | PathKind::Use) => {
+        Some(
+            PathKind::Pat
+            | PathKind::Attr { .. }
+            | PathKind::Vis { .. }
+            | PathKind::Use
+            | PathKind::Derive,
+        ) => {
             return;
         }
         _ => {

crates/ide_completion/src/completions/unqualified_path.rs

@@ -19,10 +19,11 @@ pub(crate) fn complete_unqualified_path(acc: &mut Completions, ctx: &CompletionC
         Some(PathCompletionCtx {
             kind:
                 Some(
-                    PathKind::Vis { .. }
+                    PathKind::Attr { .. }
-                    | PathKind::Attr { .. }
+                    | PathKind::Derive
+                    | PathKind::Pat
                     | PathKind::Use { .. }
-                    | PathKind::Pat,
+                    | PathKind::Vis { .. },
                 ),
             ..
         }) => return,

crates/ide_completion/src/context.rs

@@ -43,11 +43,12 @@ pub(crate) enum Visible {
     No,
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 pub(super) enum PathKind {
     Expr,
     Type,
     Attr { kind: AttrKind, annotated_item_kind: Option<SyntaxKind> },
+    Derive,
     Mac,
     Pat,
     Vis { has_in_token: bool },
@@ -472,6 +473,8 @@ impl<'a> CompletionContext<'a> {
         mut fake_ident_token: SyntaxToken,
     ) {
         let _p = profile::span("CompletionContext::expand_and_fill");
+        let mut derive_ctx = None;
+
         'expansion: loop {
             let parent_item =
                 |item: &ast::Item| item.syntax().ancestors().skip(1).find_map(ast::Item::cast);
@@ -509,11 +512,45 @@ impl<'a> CompletionContext<'a> {
                     _ => break 'expansion,
                 }
             }
+            let orig_tt = match find_node_at_offset::<ast::TokenTree>(&original_file, offset) {
+                Some(it) => it,
+                None => break,
+            };
+            let spec_tt = match find_node_at_offset::<ast::TokenTree>(&speculative_file, offset) {
+                Some(it) => it,
+                None => break,
+            };
+
+            // Expand pseudo-derive expansion
+            if let (Some(orig_attr), Some(spec_attr)) = (
+                orig_tt.syntax().parent().and_then(ast::Meta::cast).and_then(|it| it.parent_attr()),
+                spec_tt.syntax().parent().and_then(ast::Meta::cast).and_then(|it| it.parent_attr()),
+            ) {
+                match (
+                    self.sema.expand_derive_as_pseudo_attr_macro(&orig_attr),
+                    self.sema.speculative_expand_derive_as_pseudo_attr_macro(
+                        &orig_attr,
+                        &spec_attr,
+                        fake_ident_token.clone(),
+                    ),
+                ) {
+                    // Clearly not a derive macro
+                    (None, None) => (),
+                    // successful expansions
+                    (Some(actual_expansion), Some((fake_expansion, fake_mapped_token))) => {
+                        let new_offset = fake_mapped_token.text_range().start();
+                        derive_ctx = Some((actual_expansion, fake_expansion, new_offset));
+                        break 'expansion;
+                    }
+                    // exactly one expansion failed, inconsistent state so stop expanding completely
+                    _ => break 'expansion,
+                }
+            }
 
             // Expand fn-like macro calls
             if let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
-                find_node_at_offset::<ast::MacroCall>(&original_file, offset),
+                orig_tt.syntax().ancestors().find_map(ast::MacroCall::cast),
-                find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
+                spec_tt.syntax().ancestors().find_map(ast::MacroCall::cast),
             ) {
                 let mac_call_path0 = actual_macro_call.path().as_ref().map(|s| s.syntax().text());
                 let mac_call_path1 =
@@ -553,7 +590,7 @@ impl<'a> CompletionContext<'a> {
             break;
         }
 
-        self.fill(&original_file, speculative_file, offset);
+        self.fill(&original_file, speculative_file, offset, derive_ctx);
     }
 
     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
@@ -697,6 +734,7 @@ impl<'a> CompletionContext<'a> {
         original_file: &SyntaxNode,
         file_with_fake_ident: SyntaxNode,
         offset: TextSize,
+        derive_ctx: Option<(SyntaxNode, SyntaxNode, TextSize)>,
     ) {
         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
         let syntax_element = NodeOrToken::Token(fake_ident_token);
@@ -724,6 +762,21 @@ impl<'a> CompletionContext<'a> {
         self.expected_type = expected_type;
         self.expected_name = expected_name;
 
+        // Overwrite the path kind for derives
+        if let Some((original_file, file_with_fake_ident, offset)) = derive_ctx {
+            if let Some(ast::NameLike::NameRef(name_ref)) =
+                find_node_at_offset(&file_with_fake_ident, offset)
+            {
+                if let Some((path_ctx, _)) =
+                    Self::classify_name_ref(&self.sema, &original_file, name_ref)
+                {
+                    self.path_context =
+                        Some(PathCompletionCtx { kind: Some(PathKind::Derive), ..path_ctx });
+                }
+            }
+            return;
+        }
+
         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
             Some(it) => it,
             None => return,
@@ -743,6 +796,7 @@ impl<'a> CompletionContext<'a> {
             .token_ancestors_with_macros(self.token.clone())
             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
             .find_map(ast::Fn::cast);
+
         match name_like {
             ast::NameLike::Lifetime(lifetime) => {
                 self.lifetime_ctx =

crates/ide_completion/src/lib.rs

@@ -152,6 +152,7 @@ pub fn completions(
 
     let mut acc = Completions::default();
     completions::attribute::complete_attribute(&mut acc, &ctx);
+    completions::attribute::complete_derive(&mut acc, &ctx);
     completions::attribute::complete_known_attribute_input(&mut acc, &ctx);
     completions::dot::complete_dot(&mut acc, &ctx);
     completions::extern_abi::complete_extern_abi(&mut acc, &ctx);

crates/ide_completion/src/tests/attribute.rs

@@ -760,6 +760,7 @@ mod derive {
         check_derive(
             r#"
 //- proc_macros: derive_identity
+//- minicore: derive
 #[derive(der$0)] struct Test;
 "#,
             expect![[r#"
@@ -769,6 +770,7 @@ mod derive {
         check_derive(
             r#"
 //- proc_macros: derive_identity
+//- minicore: derive
 use proc_macros::DeriveIdentity;
 #[derive(der$0)] struct Test;
 "#,
@@ -784,6 +786,7 @@ use proc_macros::DeriveIdentity;
             "DeriveIdentity",
             r#"
 //- proc_macros: derive_identity
+//- minicore: derive
 #[derive(der$0)] struct Test;
 "#,
             r#"
@@ -793,6 +796,32 @@ use proc_macros::DeriveIdentity;
 "#,
         );
     }
+
+    #[test]
+    fn qualified() {
+        check_derive(
+            r#"
+//- proc_macros: derive_identity
+//- minicore: derive, copy, clone
+#[derive(proc_macros::$0)] struct Test;
+"#,
+            expect![[r#"
+                de Clone, Copy
+                de Clone
+            "#]],
+        );
+        check_derive(
+            r#"
+//- proc_macros: derive_identity
+//- minicore: derive, copy, clone
+#[derive(proc_macros::C$0)] struct Test;
+"#,
+            expect![[r#"
+                de Clone, Copy
+                de Clone
+            "#]],
+        );
+    }
 }
 
 mod lint {

crates/ide_db/src/syntax_helpers/node_ext.rs

@@ -443,7 +443,7 @@ pub fn parse_tt_as_comma_sep_paths(input: ast::TokenTree) -> Option<Vec<ast::Pat
             None => None,
             Some(tok) => Some(tok),
         });
-    let input_expressions = tokens.into_iter().group_by(|tok| tok.kind() == T![,]);
+    let input_expressions = tokens.group_by(|tok| tok.kind() == T![,]);
     let paths = input_expressions
         .into_iter()
         .filter_map(|(is_sep, group)| (!is_sep).then(|| group))