Error placement

src/tree/file_builder.rs

@@ -156,7 +156,7 @@ pub fn message<M: Into<String>>(mut self, m: M) -> Self {
 
     pub fn emit(self) {
         let message = self.message.expect("Error message not set");
-        let node = self.builder.current_id();
-        self.builder.errors.push(SyntaxErrorData { node, message })
+        let &(node, after_child) = self.builder.in_progress.last().unwrap();
+        self.builder.errors.push(SyntaxErrorData { node, message, after_child })
     }
 }

src/tree/mod.rs

@@ -2,6 +2,7 @@
 use syntax_kinds::syntax_info;
 
 use std::fmt;
+use std::cmp;
 
 mod file_builder;
 pub use self::file_builder::{FileBuilder, Sink};
@@ -96,6 +97,15 @@ fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
 	}
 }
 
+impl<'f> cmp::PartialEq<Node<'f>> for Node<'f> {
+	fn eq(&self, other: &Node<'f>) -> bool {
+		self.idx == other.idx && ::std::ptr::eq(self.file, other.file)
+	}
+}
+
+impl<'f> cmp::Eq for Node<'f> {
+}
+
 #[derive(Clone, Copy)]
 pub struct SyntaxError<'f> {
 	file: &'f File,
@@ -107,6 +117,11 @@ pub fn message(&self) -> &'f str {
 		self.data().message.as_str()
 	}
 
+	pub fn after_child(&self) -> Option<Node<'f>> {
+		let idx = self.data().after_child?;
+		Some(Node { file: self.file, idx })
+	}
+
 	fn data(&self) -> &'f SyntaxErrorData {
 		&self.file.errors[self.idx]
 	}
@@ -187,6 +202,7 @@ fn index_mut(&mut self, NodeIdx(idx): NodeIdx) -> &mut NodeData {
 struct SyntaxErrorData {
 	node: NodeIdx,
 	message: String,
+	after_child: Option<NodeIdx>,
 }
 
 impl ::std::ops::Index<ErrorIdx> for Vec<SyntaxErrorData> {

tests/data/parser/err/0000_struct_field_missing_comma.txt

@@ -1,5 +1,5 @@
 FILE@[0; 34)
-  STRUCT_ITEM@[0; 34) err: `expected COMMA`
+  STRUCT_ITEM@[0; 34)
     STRUCT_KW@[0; 6)
     WHITESPACE@[6; 7)
     IDENT@[7; 8)
@@ -12,9 +12,11 @@ FILE@[0; 34)
       WHITESPACE@[17; 18)
       IDENT@[18; 21)
       WHITESPACE@[21; 26)
+    err: `expected COMMA`
     STRUCT_FIELD@[26; 33)
       IDENT@[26; 27)
       COLON@[27; 28)
       WHITESPACE@[28; 29)
       IDENT@[29; 32)
-      WHITESPACE@[32;
+      WHITESPACE@[32; 33)
+    R_CURLY@[33; 34)

tests/parser.rs

@@ -7,7 +7,7 @@
 use std::fs::read_dir;
 use std::fmt::Write;
 
-use libsyntax2::{tokenize, parse, Token, Node, File, FileBuilder};
+use libsyntax2::{tokenize, parse, Node, File};
 
 #[test]
 fn parser_tests() {
@@ -70,14 +70,24 @@ fn dump_tree(file: &File) -> String {
 
     fn go(node: Node, buff: &mut String, level: usize) {
         buff.push_str(&String::from("  ").repeat(level));
-        write!(buff, "{:?}", node).unwrap();
-        for err in node.errors() {
-            write!(buff, " err: `{}`", err.message()).unwrap();
+        write!(buff, "{:?}\n", node).unwrap();
+        let my_errors = node.errors().filter(|e| e.after_child().is_none());
+        let parent_errors = node.parent().into_iter()
+            .flat_map(|n| n.errors())
+            .filter(|e| e.after_child() == Some(node));
+
+        for err in my_errors {
+            buff.push_str(&String::from("  ").repeat(level));
+            write!(buff, "err: `{}`\n", err.message()).unwrap();
         }
-        write!(buff, "\n").unwrap();
 
         for child in node.children() {
             go(child, buff, level + 1)
         }
+
+        for err in parent_errors {
+            buff.push_str(&String::from("  ").repeat(level));
+            write!(buff, "err: `{}`\n", err.message()).unwrap();
+        }
     }
 }