Merge #10029

10029: internal: Improve expand_macro r=Veykril a=Veykril

- Adds a few more newlines to the output making it more readable
- Fixes a bug with multiple derives not being expandable

There seems to be an issue with multiple derives in one attribute only showing the expansion of the last derive which I'll have to investigate.
bors r+

Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

crates/hir_def/src/item_scope.rs

@@ -8,6 +8,7 @@ use hir_expand::{name::Name, AstId, MacroCallId, MacroDefKind};
 use once_cell::sync::Lazy;
 use profile::Count;
 use rustc_hash::{FxHashMap, FxHashSet};
+use smallvec::SmallVec;
 use stdx::format_to;
 use syntax::ast;
 
@@ -61,7 +62,7 @@ pub struct ItemScope {
     // be all resolved to the last one defined if shadowing happens.
     legacy_macros: FxHashMap<Name, MacroDefId>,
     attr_macros: FxHashMap<AstId<ast::Item>, MacroCallId>,
-    derive_macros: FxHashMap<AstId<ast::Item>, (AttrId, MacroCallId)>,
+    derive_macros: FxHashMap<AstId<ast::Item>, SmallVec<[(AttrId, MacroCallId); 1]>>,
 }
 
 pub(crate) static BUILTIN_SCOPE: Lazy<FxHashMap<Name, PerNs>> = Lazy::new(|| {
@@ -189,13 +190,13 @@ impl ItemScope {
         call: MacroCallId,
         attr_id: AttrId,
     ) {
-        self.derive_macros.insert(item, (attr_id, call));
+        self.derive_macros.entry(item).or_default().push((attr_id, call));
     }
 
     pub(crate) fn derive_macro_invocs(
         &self,
     ) -> impl Iterator<Item = (AstId<ast::Item>, (AttrId, MacroCallId))> + '_ {
-        self.derive_macros.iter().map(|(k, v)| (*k, *v))
+        self.derive_macros.iter().flat_map(|(k, v)| v.iter().map(move |v| (*k, *v)))
     }
 
     pub(crate) fn unnamed_trait_vis(&self, tr: TraitId) -> Option<Visibility> {

crates/ide/src/expand_macro.rs

@@ -3,7 +3,7 @@ use std::iter;
 use hir::Semantics;
 use ide_db::{helpers::pick_best_token, RootDatabase};
 use itertools::Itertools;
-use syntax::{ast, ted, AstNode, NodeOrToken, SyntaxKind, SyntaxKind::*, SyntaxNode, WalkEvent, T};
+use syntax::{ast, ted, AstNode, NodeOrToken, SyntaxKind, SyntaxNode, WalkEvent, T};
 
 use crate::FilePosition;
 
@@ -31,21 +31,22 @@ pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<
         SyntaxKind::IDENT => 1,
         _ => 0,
     })?;
+    let descended = sema.descend_into_macros(tok.clone());
+    if let Some(attr) = descended.ancestors().find_map(ast::Attr::cast) {
+        if let Some((path, tt)) = attr.as_simple_call() {
+            if path == "derive" {
+                let mut tt = tt.syntax().children_with_tokens().skip(1).join("");
+                tt.pop();
+                return sema
+                    .expand_derive_macro(&attr)
+                    .map(insert_whitespaces)
+                    .map(|expansion| ExpandedMacro { name: tt, expansion });
+            }
+        }
+    }
     let mut expanded = None;
     let mut name = None;
     for node in tok.ancestors() {
-        if let Some(attr) = ast::Attr::cast(node.clone()) {
-            if let Some((path, tt)) = attr.as_simple_call() {
-                if path == "derive" {
-                    let mut tt = tt.syntax().children_with_tokens().skip(1).join("");
-                    tt.pop();
-                    name = Some(tt);
-                    expanded = sema.expand_derive_macro(&attr);
-                    break;
-                }
-            }
-        }
-
         if let Some(item) = ast::Item::cast(node.clone()) {
             if let Some(def) = sema.resolve_attr_macro_call(&item) {
                 name = def.name(db).map(|name| name.to_string());
@@ -53,7 +54,6 @@ pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<
                 break;
             }
         }
-
         if let Some(mac) = ast::MacroCall::cast(node) {
             name = Some(mac.path()?.segment()?.name_ref()?.to_string());
             expanded = expand_macro_recur(&sema, &mac);
@@ -107,24 +107,26 @@ fn expand<T: AstNode>(
 // FIXME: It would also be cool to share logic here and in the mbe tests,
 // which are pretty unreadable at the moment.
 fn insert_whitespaces(syn: SyntaxNode) -> String {
+    use SyntaxKind::*;
     let mut res = String::new();
-    let mut token_iter = syn
-        .preorder_with_tokens()
-        .filter_map(|event| {
-            if let WalkEvent::Enter(NodeOrToken::Token(token)) = event {
-                Some(token)
-            } else {
-                None
-            }
-        })
-        .peekable();
 
     let mut indent = 0;
     let mut last: Option<SyntaxKind> = None;
 
-    while let Some(token) = token_iter.next() {
-        let mut is_next = |f: fn(SyntaxKind) -> bool, default| -> bool {
-            token_iter.peek().map(|it| f(it.kind())).unwrap_or(default)
+    for event in syn.preorder_with_tokens() {
+        let token = match event {
+            WalkEvent::Enter(NodeOrToken::Token(token)) => token,
+            WalkEvent::Leave(NodeOrToken::Node(node))
+                if matches!(node.kind(), ATTR | MATCH_ARM | STRUCT | ENUM | UNION | FN | IMPL) =>
+            {
+                res.push('\n');
+                res.extend(iter::repeat(" ").take(2 * indent));
+                continue;
+            }
+            _ => continue,
+        };
+        let is_next = |f: fn(SyntaxKind) -> bool, default| -> bool {
+            token.next_token().map(|it| f(it.kind())).unwrap_or(default)
         };
         let is_last =
             |f: fn(SyntaxKind) -> bool, default| -> bool { last.map(f).unwrap_or(default) };
@@ -182,6 +184,7 @@ mod tests {
 
     use crate::fixture;
 
+    #[track_caller]
     fn check(ra_fixture: &str, expect: Expect) {
         let (analysis, pos) = fixture::position(ra_fixture);
         let expansion = analysis.expand_macro(pos).unwrap().unwrap();
@@ -207,6 +210,7 @@ f$0oo!();
             expect![[r#"
                 foo
                 fn b(){}
+
             "#]],
         );
     }
@@ -226,11 +230,12 @@ macro_rules! foo {
 f$0oo!();
         "#,
             expect![[r#"
-            foo
-            fn some_thing() -> u32 {
-              let a = 0;
-              a+10
-            }"#]],
+                foo
+                fn some_thing() -> u32 {
+                  let a = 0;
+                  a+10
+                }
+            "#]],
         );
     }
 
@@ -343,7 +348,6 @@ fn main() {
     fn macro_expand_derive() {
         check(
             r#"
-
 #[rustc_builtin_macro]
 pub macro Clone {}
 
@@ -353,6 +357,28 @@ struct Foo {}
             expect![[r#"
                 Clone
                 impl< >crate::clone::Clone for Foo< >{}
+
+            "#]],
+        );
+    }
+
+    #[test]
+    fn macro_expand_derive2() {
+        check(
+            r#"
+#[rustc_builtin_macro]
+pub macro Clone {}
+#[rustc_builtin_macro]
+pub macro Copy {}
+
+#[derive(Cop$0y)]
+#[derive(Clone)]
+struct Foo {}
+"#,
+            expect![[r#"
+                Copy
+                impl< >crate::marker::Copy for Foo< >{}
+
             "#]],
         );
     }