MFC r307227 and r307343:

  Improve typing of POSIX search tree functions.

  Back in 2015 when I reimplemented these functions to use an AVL tree, I
  was annoyed by the weakness of the typing of these functions. Both tree
  nodes and keys are represented by 'void *', meaning that things like the
  documentation for these functions are an absolute train wreck.

  To make things worse, users of these functions need to cast the return
  value of tfind()/tsearch() from 'void *' to 'type_of_key **' in order to
  access the key. Technically speaking such casts violate aliasing rules.
  I've observed actual breakages as a result of this by enabling features
  like LTO.

  I've filed a bug report at the Austin Group. Looking at the way the bug
  got resolved, they made a pretty good step in the right direction. A new
  type 'posix_tnode' has been added to correspond to tree nodes. It is
  still defined as 'void' for source-level compatibility, but in the very
  far future it could be replaced by a proper structure type containing a
  key pointer.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/libc/tests/stdlib/tsearch_test.c b/lib/libc/tests/stdlib/tsearch_test.c
index b08fd94..88c62f5 100644
--- a/lib/libc/tests/stdlib/tsearch_test.c
+++ b/lib/libc/tests/stdlib/tsearch_test.c
@@ -34,7 +34,7 @@ __FBSDID("$FreeBSD$");
 
 /* Validates the integrity of an AVL tree. */
 static inline unsigned int
-tnode_assert(const node_t *n)
+tnode_assert(const posix_tnode *n)
 {
 	unsigned int height_left, height_right;
 	int balance;
@@ -79,7 +79,7 @@ ATF_TC_BODY(tsearch_test, tc)
 		keys[i] = i;
 
 	/* Apply random operations on a binary tree and check the results. */
-	void *root = NULL;
+	posix_tnode *root = NULL;
 	bool present[NKEYS] = {};
 	for (int i = 0; i < NKEYS * 10; ++i) {
 		int key = nrand48(random_state) % NKEYS;