Replace expressions with errors in them

7 files changed, 84 insertions, 33 deletions

diff --git a/crates/hir_def/src/macro_expansion_tests.rs b/crates/hir_def/src/macro_expansion_tests.rs
index 28a5d960859..1a7d9aa8411 100644
--- a/crates/hir_def/src/macro_expansion_tests.rs
+++ b/crates/hir_def/src/macro_expansion_tests.rs
@@ -186,7 +186,7 @@ pub fn identity_when_valid(_attr: TokenStream, item: TokenStream) -> TokenStream
         let range: Range<usize> = range.into();
 
         if show_token_ids {
-            if let Some((tree, map)) = arg.as_deref() {
+            if let Some((tree, map, _)) = arg.as_deref() {
                 let tt_range = call.token_tree().unwrap().syntax().text_range();
                 let mut ranges = Vec::new();
                 extract_id_ranges(&mut ranges, &map, &tree);
diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index 7a21e3e8701..eea02898d2c 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -108,7 +108,10 @@ pub trait AstDatabase: SourceDatabase {
 
     /// Lowers syntactic macro call to a token tree representation.
     #[salsa::transparent]
-    fn macro_arg(&self, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>>;
+    fn macro_arg(
+        &self,
+        id: MacroCallId,
+    ) -> Option<Arc<(tt::Subtree, mbe::TokenMap, fixup::SyntaxFixupMap)>>;
     /// Extracts syntax node, corresponding to a macro call. That's a firewall
     /// query, only typing in the macro call itself changes the returned
     /// subtree.
@@ -291,29 +294,27 @@ fn parse_macro_expansion(
     }
 }
 
-fn macro_arg(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>> {
+fn macro_arg(
+    db: &dyn AstDatabase,
+    id: MacroCallId,
+) -> Option<Arc<(tt::Subtree, mbe::TokenMap, fixup::SyntaxFixupMap)>> {
     let arg = db.macro_arg_text(id)?;
     let loc = db.lookup_intern_macro_call(id);
 
     let node = SyntaxNode::new_root(arg);
-    eprintln!("input text:\n{node}");
-    eprintln!("input syntax:\n{node:#?}");
     let censor = censor_for_macro_input(&loc, &node);
     // TODO only fixup for attribute macro input
     let mut fixups = fixup::fixup_syntax(&node);
     fixups.replace.extend(censor.into_iter().map(|node| (node, Vec::new())));
-    eprintln!("fixups: {fixups:?}");
     let (mut tt, tmap) =
         mbe::syntax_node_to_token_tree_censored(&node, fixups.replace, fixups.append);
 
-    eprintln!("fixed-up input: {}", tt);
-
     if loc.def.is_proc_macro() {
         // proc macros expect their inputs without parentheses, MBEs expect it with them included
         tt.delimiter = None;
     }
 
-    Some(Arc::new((tt, tmap)))
+    Some(Arc::new((tt, tmap, fixups.map)))
 }
 
 fn censor_for_macro_input(loc: &MacroCallLoc, node: &SyntaxNode) -> FxHashSet<SyntaxNode> {
@@ -433,7 +434,6 @@ fn macro_expand(db: &dyn AstDatabase, id: MacroCallId) -> ExpandResult<Option<Ar
     let ExpandResult { value: mut tt, err } = expander.expand(db, id, &macro_arg.0);
     // Set a hard limit for the expanded tt
     let count = tt.count();
-    // XXX: Make ExpandResult a real error and use .map_err instead?
     if TOKEN_LIMIT.check(count).is_err() {
         return ExpandResult::str_err(format!(
             "macro invocation exceeds token limit: produced {} tokens, limit is {}",
@@ -442,7 +442,7 @@ fn macro_expand(db: &dyn AstDatabase, id: MacroCallId) -> ExpandResult<Option<Ar
         ));
     }
 
-    fixup::reverse_fixups(&mut tt, &macro_arg.1);
+    fixup::reverse_fixups(&mut tt, &macro_arg.1, &macro_arg.2);
 
     ExpandResult { value: Some(Arc::new(tt)), err }
 }
diff --git a/crates/hir_expand/src/fixup.rs b/crates/hir_expand/src/fixup.rs
index a4acf9e987e..c98d20e4561 100644
--- a/crates/hir_expand/src/fixup.rs
+++ b/crates/hir_expand/src/fixup.rs
@@ -10,21 +10,39 @@ use tt::Subtree;
 pub struct SyntaxFixups {
     pub append: FxHashMap<SyntaxNode, Vec<SyntheticToken>>,
     pub replace: FxHashMap<SyntaxNode, Vec<SyntheticToken>>,
+    pub map: SyntaxFixupMap,
 }
 
+#[derive(Debug, PartialEq, Eq)]
+pub struct SyntaxFixupMap {
+    original: Vec<(Subtree, TokenMap)>,
+}
+
+const EMPTY_ID: SyntheticTokenId = SyntheticTokenId(!0);
+
 pub fn fixup_syntax(node: &SyntaxNode) -> SyntaxFixups {
     let mut append = FxHashMap::default();
     let mut replace = FxHashMap::default();
     let mut preorder = node.preorder();
-    let empty_id = SyntheticTokenId(0);
+    let mut original = Vec::new();
     while let Some(event) = preorder.next() {
         let node = match event {
             syntax::WalkEvent::Enter(node) => node,
             syntax::WalkEvent::Leave(_) => continue,
         };
-        if node.kind() == SyntaxKind::ERROR {
-            // TODO this might not be helpful
-            replace.insert(node, Vec::new());
+        if can_handle_error(&node) && has_error_to_handle(&node) {
+            // the node contains an error node, we have to completely replace it by something valid
+            let original_tree = mbe::syntax_node_to_token_tree(&node);
+            // TODO handle token ids / token map
+            let idx = original.len() as u32;
+            original.push(original_tree);
+            let replacement = SyntheticToken {
+                kind: SyntaxKind::IDENT,
+                text: "__ra_fixup".into(),
+                range: node.text_range(),
+                id: SyntheticTokenId(idx),
+            };
+            replace.insert(node.clone(), vec![replacement]);
             preorder.skip_subtree();
             continue;
         }
@@ -39,7 +57,7 @@ pub fn fixup_syntax(node: &SyntaxNode) -> SyntaxFixups {
                                 kind: SyntaxKind::IDENT,
                                 text: "__ra_fixup".into(),
                                 range: end_range,
-                                id: empty_id,
+                                id: EMPTY_ID,
                             },
                         ]);
                     }
@@ -51,7 +69,7 @@ pub fn fixup_syntax(node: &SyntaxNode) -> SyntaxFixups {
                                 kind: SyntaxKind::SEMICOLON,
                                 text: ";".into(),
                                 range: end_range,
-                                id: empty_id,
+                                id: EMPTY_ID,
                             },
                         ]);
                     }
@@ -60,18 +78,37 @@ pub fn fixup_syntax(node: &SyntaxNode) -> SyntaxFixups {
             }
         }
     }
-    SyntaxFixups { append, replace }
+    SyntaxFixups { append, replace, map: SyntaxFixupMap { original } }
+}
+
+fn has_error(node: &SyntaxNode) -> bool {
+    node.children().any(|c| c.kind() == SyntaxKind::ERROR)
+}
+
+fn can_handle_error(node: &SyntaxNode) -> bool {
+    ast::Expr::can_cast(node.kind())
+}
+
+fn has_error_to_handle(node: &SyntaxNode) -> bool {
+    has_error(node) || node.children().any(|c| !can_handle_error(&c) && has_error_to_handle(&c))
 }
 
-pub fn reverse_fixups(tt: &mut Subtree, token_map: &TokenMap) {
-    eprintln!("token_map: {:?}", token_map);
+pub fn reverse_fixups(tt: &mut Subtree, token_map: &TokenMap, fixup_map: &SyntaxFixupMap) {
     tt.token_trees.retain(|tt| match tt {
-        tt::TokenTree::Leaf(leaf) => token_map.synthetic_token_id(leaf.id()).is_none(),
+        tt::TokenTree::Leaf(leaf) => {
+            token_map.synthetic_token_id(leaf.id()).is_none()
+                || token_map.synthetic_token_id(leaf.id()) != Some(EMPTY_ID)
+        }
         _ => true,
     });
     tt.token_trees.iter_mut().for_each(|tt| match tt {
-        tt::TokenTree::Subtree(tt) => reverse_fixups(tt, token_map),
-        _ => {}
+        tt::TokenTree::Subtree(tt) => reverse_fixups(tt, token_map, fixup_map),
+        tt::TokenTree::Leaf(leaf) => {
+            if let Some(id) = token_map.synthetic_token_id(leaf.id()) {
+                let (original, _original_tmap) = &fixup_map.original[id.0 as usize];
+                *tt = tt::TokenTree::Subtree(original.clone());
+            }
+        }
     });
 }
 
@@ -84,6 +121,7 @@ mod tests {
     #[track_caller]
     fn check(ra_fixture: &str, mut expect: Expect) {
         let parsed = syntax::SourceFile::parse(ra_fixture);
+        eprintln!("parse: {:#?}", parsed.syntax_node());
         let fixups = super::fixup_syntax(&parsed.syntax_node());
         let (mut tt, tmap) = mbe::syntax_node_to_token_tree_censored(
             &parsed.syntax_node(),
@@ -106,7 +144,7 @@ mod tests {
             parse.syntax_node()
         );
 
-        reverse_fixups(&mut tt, &tmap);
+        reverse_fixups(&mut tt, &tmap, &fixups.map);
 
         // the fixed-up + reversed version should be equivalent to the original input
         // (but token IDs don't matter)
@@ -172,4 +210,18 @@ fn foo () {a . b ; bar () ;}
 "#]],
         )
     }
+
+    #[test]
+    fn extraneous_comma() {
+        check(
+            r#"
+fn foo() {
+    bar(,);
+}
+"#,
+            expect![[r#"
+fn foo () {__ra_fixup ;}
+"#]],
+        )
+    }
 }
diff --git a/crates/hir_expand/src/hygiene.rs b/crates/hir_expand/src/hygiene.rs
index d2b719bf570..0ac5ee83064 100644
--- a/crates/hir_expand/src/hygiene.rs
+++ b/crates/hir_expand/src/hygiene.rs
@@ -15,6 +15,7 @@ use syntax::{
 
 use crate::{
     db::{self, AstDatabase},
+    fixup,
     name::{AsName, Name},
     HirFileId, HirFileIdRepr, InFile, MacroCallKind, MacroCallLoc, MacroDefKind, MacroFile,
 };
@@ -127,7 +128,7 @@ struct HygieneInfo {
     attr_input_or_mac_def_start: Option<InFile<TextSize>>,
 
     macro_def: Arc<TokenExpander>,
-    macro_arg: Arc<(tt::Subtree, mbe::TokenMap)>,
+    macro_arg: Arc<(tt::Subtree, mbe::TokenMap, fixup::SyntaxFixupMap)>,
     macro_arg_shift: mbe::Shift,
     exp_map: Arc<mbe::TokenMap>,
 }
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index b23d5472426..6ec507d00f3 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -427,7 +427,7 @@ pub struct ExpansionInfo {
     attr_input_or_mac_def: Option<InFile<ast::TokenTree>>,
 
     macro_def: Arc<TokenExpander>,
-    macro_arg: Arc<(tt::Subtree, mbe::TokenMap)>,
+    macro_arg: Arc<(tt::Subtree, mbe::TokenMap, fixup::SyntaxFixupMap)>,
     /// A shift built from `macro_arg`'s subtree, relevant for attributes as the item is the macro arg
     /// and as such we need to shift tokens if they are part of an attributes input instead of their item.
     macro_arg_shift: mbe::Shift,
diff --git a/crates/mbe/src/syntax_bridge.rs b/crates/mbe/src/syntax_bridge.rs
index 7feaaaa62d8..da7fdb74ee8 100644
--- a/crates/mbe/src/syntax_bridge.rs
+++ b/crates/mbe/src/syntax_bridge.rs
@@ -30,8 +30,8 @@ pub fn syntax_node_to_token_tree_censored(
     let mut c = Convertor::new(node, global_offset, replace, append);
     let subtree = convert_tokens(&mut c);
     c.id_alloc.map.shrink_to_fit();
-    always!(c.replace.is_empty());
-    always!(c.append.is_empty());
+    always!(c.replace.is_empty(), "replace: {:?}", c.replace);
+    always!(c.append.is_empty(), "append: {:?}", c.append);
     (subtree, c.id_alloc.map)
 }
 
@@ -539,7 +539,6 @@ impl Convertor {
                 WalkEvent::Enter(ele) => ele,
                 WalkEvent::Leave(SyntaxElement::Node(node)) => {
                     if let Some(mut v) = append.remove(&node) {
-                        eprintln!("after {:?}, appending {:?}", node, v);
                         if !v.is_empty() {
                             v.reverse();
                             return (None, v);
@@ -554,7 +553,6 @@ impl Convertor {
                 SyntaxElement::Node(node) => {
                     if let Some(mut v) = replace.remove(&node) {
                         preorder.skip_subtree();
-                        eprintln!("replacing {:?} by {:?}", node, v);
                         if !v.is_empty() {
                             v.reverse();
                             return (None, v);
@@ -640,8 +638,8 @@ impl TokenConvertor for Convertor {
                 self.current = new_current;
                 self.current_synthetic = new_synth;
             }
-            // TODO fix range?
-            return Some((SynToken::Synthetic(synth_token), self.range));
+            let range = synth_token.range;
+            return Some((SynToken::Synthetic(synth_token), range));
         }
 
         let curr = self.current.clone()?;
@@ -675,7 +673,6 @@ impl TokenConvertor for Convertor {
         }
 
         if let Some(synth_token) = self.current_synthetic.last() {
-            // TODO fix range?
             return Some(SynToken::Synthetic(synth_token.clone()));
         }
 
diff --git a/crates/mbe/src/token_map.rs b/crates/mbe/src/token_map.rs
index ee1090945cb..c923e7a69a1 100644
--- a/crates/mbe/src/token_map.rs
+++ b/crates/mbe/src/token_map.rs
@@ -74,6 +74,7 @@ impl TokenMap {
 
     pub(crate) fn shrink_to_fit(&mut self) {
         self.entries.shrink_to_fit();
+        self.synthetic_entries.shrink_to_fit();
     }
 
     pub(crate) fn insert(&mut self, token_id: tt::TokenId, relative_range: TextRange) {