Ensure that LHS and RHS syntax nodes have different IDs

src/dijkstra.rs

@@ -609,7 +609,6 @@ mod tests {
             "]",
             pos_helper(2),
         )];
-        init_info(&lhs);
 
         let rhs = vec![Syntax::new_list(
             &arena,
@@ -619,7 +618,7 @@ mod tests {
             "]",
             pos_helper(2),
         )];
-        init_info(&rhs);
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -653,7 +652,6 @@ mod tests {
             "]",
             pos_helper(2),
         )];
-        init_info(&lhs);
 
         let rhs = vec![Syntax::new_list(
             &arena,
@@ -666,7 +664,7 @@ mod tests {
             "]",
             pos_helper(3),
         )];
-        init_info(&rhs);
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -704,7 +702,6 @@ mod tests {
             "]",
             pos_helper(4),
         )];
-        init_info(&lhs);
 
         let rhs = vec![Syntax::new_list(
             &arena,
@@ -717,7 +714,7 @@ mod tests {
             "}",
             pos_helper(4),
         )];
-        init_info(&rhs);
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -752,10 +749,9 @@ mod tests {
             Syntax::new_atom(&arena, col_helper(2, 0), "bar"),
             Syntax::new_atom(&arena, col_helper(2, 1), "foo"),
         ];
-        init_info(&lhs);
 
         let rhs = vec![Syntax::new_atom(&arena, col_helper(1, 0), "foo")];
-        init_info(&rhs);
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -790,9 +786,9 @@ mod tests {
             "]",
             pos_helper(2),
         )];
-        init_info(&lhs);
 
         let rhs = vec![];
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -827,9 +823,9 @@ mod tests {
             ),
             Syntax::new_atom(&arena, col_helper(2, 2), ";"),
         ];
-        init_info(&lhs);
 
         let rhs = vec![];
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -884,7 +880,6 @@ mod tests {
             "]",
             pos_helper(100),
         )];
-        init_info(&lhs);
 
         let rhs = vec![Syntax::new_list(
             &arena,
@@ -917,7 +912,7 @@ mod tests {
             "]",
             pos_helper(100),
         )];
-        init_info(&rhs);
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -950,14 +945,13 @@ mod tests {
             pos_helper(1),
             "the quick brown fox",
         )];
-        init_info(&lhs);
 
         let rhs = vec![Syntax::new_comment(
             &arena,
             pos_helper(1),
             "the quick brown cat",
         )];
-        init_info(&rhs);
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -985,10 +979,9 @@ mod tests {
             pos_helper(1),
             "the quick brown fox",
         )];
-        init_info(&lhs);
 
         let rhs = vec![Syntax::new_comment(&arena, pos_helper(1), "foo bar")];
-        init_info(&rhs);
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),
@@ -1015,14 +1008,13 @@ mod tests {
             Syntax::new_comment(&arena, pos_helper(1), "the quick brown fox"),
             Syntax::new_comment(&arena, pos_helper(2), "the quick brown thing"),
         ];
-        init_info(&lhs);
 
         let rhs = vec![Syntax::new_comment(
             &arena,
             pos_helper(1),
             "the quick brown fox.",
         )];
-        init_info(&rhs);
+        init_info(&lhs, &rhs);
 
         let start = Vertex {
             lhs_syntax: lhs.get(0).copied(),

src/main.rs

@@ -20,7 +20,7 @@ use typed_arena::Arena;
 use crate::dijkstra::mark_syntax;
 use crate::files::{is_probably_binary, read_or_die};
 use crate::lines::{join_overlapping, visible_groups, MaxLine};
-use crate::syntax::{change_positions, init_info, matching_lines};
+use crate::syntax::{change_positions, init_info, init_info_single, matching_lines};
 use crate::tree_sitter_parser as tsp;
 
 extern crate pretty_env_logger;
@@ -183,7 +183,7 @@ fn main() {
                     let bytes = read_or_die(&path);
                     let src = String::from_utf8_lossy(&bytes).to_string();
                     let ast = tsp::parse(&arena, &src, &ts_lang);
-                    init_info(&ast);
+                    init_info_single(&ast, 0);
                     println!("{:#?}", ast);
                 }
                 None => {
@@ -249,8 +249,7 @@ fn main() {
 
     println!("{}", style::header(&display_path, &lang_name));
 
-    init_info(&lhs);
+    init_info(&lhs, &rhs);
-    init_info(&rhs);
     mark_syntax(lhs.get(0).copied(), rhs.get(0).copied());
 
     let lhs_positions = change_positions(&lhs_src, &rhs_src, &lhs);

src/syntax.rs

@@ -444,11 +444,20 @@ impl<'a> Syntax<'a> {
     }
 }
 
-pub fn init_info<'a>(roots: &[&'a Syntax<'a>]) {
+pub fn init_info<'a>(lhs_roots: &[&'a Syntax<'a>], rhs_roots: &[&'a Syntax<'a>]) {
-    set_unique_id(roots, 0);
+    let next_id = init_info_single(lhs_roots, 0);
+    init_info_single(rhs_roots, next_id);
+}
+
+/// Initialise all the fields in SyntaxInfo.
+///
+/// Return the next unique ID available, so we can ensure LHS and RHS
+/// have different IDs.
+pub fn init_info_single<'a>(roots: &[&'a Syntax<'a>], first_id: u64) -> u64 {
     set_next(roots, None);
     set_prev(roots, None);
     set_num_ancestors(roots, 0);
+    set_unique_id(roots, first_id)
 }
 
 fn set_unique_id<'a>(nodes: &[&'a Syntax<'a>], prev_id: u64) -> u64 {