Merge #10506

10506: Add comment r=lnicola a=k-nasa

## Why


This code looks logic-bug ...


https://github.com/rust-analyzer/rust-analyzer/blob/ce86534e1cb22685e83c3f91ea89025edbfcbc98/crates/syntax/src/syntax_node.rs#L50


However, this code has been intentionally disabled.
It's a good idea to write a comment

ref: #10357

## What

- I added comment

Co-authored-by: k-nasa <[email protected]>

Author: bors[bot]

crates/syntax/src/syntax_node.rs

@@ -47,6 +47,7 @@ impl SyntaxTreeBuilder {
 
     pub fn finish(self) -> Parse<SyntaxNode> {
         let (green, errors) = self.finish_raw();
+        // Disable block validation, see https://github.com/rust-analyzer/rust-analyzer/pull/10357
         if cfg!(debug_assertions) && false {
             let node = SyntaxNode::new_root(green.clone());
             crate::validation::validate_block_structure(&node);