[binutils-gdb] Specialize std::hash for ptid_t

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=9a343d2bb57c4555dedad9b43907aeeda7b51dae

commit 9a343d2bb57c4555dedad9b43907aeeda7b51dae
Author: Tom Tromey <tromey@adacore.com>
Date:   Mon Sep 11 08:45:37 2023 -0600

    Specialize std::hash for ptid_t
    
    This changes hash_ptid to instead be a specialization of std::hash.
    This makes it a little easier to use with standard containers.
    
    Approved-By: Simon Marchi <simon.marchi@efficios.com>

Diff:
---
 gdb/inferior.h    | 2 +-
 gdb/regcache.c    | 2 +-
 gdbsupport/ptid.h | 5 ++---
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/gdb/inferior.h b/gdb/inferior.h
index 04672582984..29c90d15efa 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -462,7 +462,7 @@ public:
 
   /* A map of ptid_t to thread_info*, for average O(1) ptid_t lookup.
      Exited threads do not appear in the map.  */
-  std::unordered_map<ptid_t, thread_info *, hash_ptid> ptid_thread_map;
+  std::unordered_map<ptid_t, thread_info *> ptid_thread_map;
 
   /* Returns a range adapter covering the inferior's threads,
      including exited threads.  Used like this:
diff --git a/gdb/regcache.c b/gdb/regcache.c
index 9b71931bb0b..91b20b7a2a2 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -329,7 +329,7 @@ reg_buffer::assert_regnum (int regnum) const
    regcaches, associated to different gdbarches).  */
 
 using ptid_regcache_map
-  = std::unordered_multimap<ptid_t, regcache_up, hash_ptid>;
+  = std::unordered_multimap<ptid_t, regcache_up>;
 
 /* Type holding regcaches for a given pid.  */
 
diff --git a/gdbsupport/ptid.h b/gdbsupport/ptid.h
index aa296b83181..f8644d47633 100644
--- a/gdbsupport/ptid.h
+++ b/gdbsupport/ptid.h
@@ -157,9 +157,8 @@ private:
   tid_type m_tid;
 };
 
-/* Functor to hash a ptid.  */
-
-struct hash_ptid
+template<>
+struct std::hash<ptid_t>
 {
   size_t operator() (const ptid_t &ptid) const
   {