rust: Add comment inside block [PR119342]

Inside a BLOCK node, all of the variables of the scope/block
are chained together and that connects them to the block.
This just adds a comment to that effect as reading the code
it is not so obvious why they need to be chained together.

gcc/rust/ChangeLog:

	PR rust/119342
	* rust-gcc.cc (block): Add comment on why chaining
	the variables of the scope toether.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

diff --git a/gcc/rust/rust-gcc.cc b/gcc/rust/rust-gcc.cc
index 85743c472cf5da1af0e7ef0e45c662e189c9eac8..524cee71a6e8c3577e543d6707199c5e1f157dd6 100644 (file)
--- a/gcc/rust/rust-gcc.cc
+++ b/gcc/rust/rust-gcc.cc
@@ -1792,6 +1792,8 @@ block (tree fndecl, tree enclosing, const std::vector<Bvariable *> &vars,
       *pp = block_tree;
     }
 
+  // Chain the variables of the scope together so they are all connected
+  // to the block.
   tree *pp = &BLOCK_VARS (block_tree);
   for (Bvariable *bv : vars)
     {