[gcc r15-5033] libstdc++: Improve comment for _Hashtable::_M_insert_unique_node

[Jonathan Wakely]

https://gcc.gnu.org/g:e97179bacd067ccd3ee765632e0c034df152ccb6

commit r15-5033-ge97179bacd067ccd3ee765632e0c034df152ccb6
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Nov 7 16:51:58 2024 +0000

    libstdc++: Improve comment for _Hashtable::_M_insert_unique_node
    
    Clarify the effects if rehashing is needed. Document the __n_elt
    parameter.
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/hashtable.h (_M_insert_unique_node): Improve
            comment.

Diff:
---
 libstdc++-v3/include/bits/hashtable.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/include/bits/hashtable.h b/libstdc++-v3/include/bits/hashtable.h
index bd514cab798d..6bcba2de368e 100644
--- a/libstdc++-v3/include/bits/hashtable.h
+++ b/libstdc++-v3/include/bits/hashtable.h
@@ -893,9 +893,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       pair<__node_ptr, __hash_code>
       _M_compute_hash_code(__node_ptr __hint, const key_type& __k) const;
 
-      // Insert node __n with hash code __code, in bucket __bkt if no
-      // rehash (assumes no element with same key already present).
+      // Insert node __n with hash code __code, in bucket __bkt (or another
+      // bucket if rehashing is needed).
+      // Assumes no element with equivalent key is already present.
       // Takes ownership of __n if insertion succeeds, throws otherwise.
+      // __n_elt is an estimated number of elements we expect to insert,
+      // used as a hint for rehashing when inserting a range.
       iterator
       _M_insert_unique_node(size_type __bkt, __hash_code,
 			    __node_ptr __n, size_type __n_elt = 1);