Remove gdb::hash_enum

gdb::hash_enum is a workaround for a small oversight in C++11:
std::hash was not defined for enumeration types.  This was rectified
in C++14 and so we can remove the local workaround.

Approved-By: Simon Marchi <simon.marchi@efficios.com>

gdb/dwarf2/aranges.c

diff --git a/gdb/dwarf2/aranges.c b/gdb/dwarf2/aranges.c
index 0d1dc11..e391ca6 100644
--- a/gdb/dwarf2/aranges.c
+++ b/gdb/dwarf2/aranges.c
@@ -38,9 +38,7 @@ read_addrmap_from_aranges (dwarf2_per_objfile *per_objfile,
   struct gdbarch *gdbarch = objfile->arch ();
   dwarf2_per_bfd *per_bfd = per_objfile->per_bfd;
 
-  std::unordered_map<sect_offset,
-		     dwarf2_per_cu_data *,
-		     gdb::hash_enum<sect_offset>>
+  std::unordered_map<sect_offset, dwarf2_per_cu_data *>
     debug_info_offset_to_per_cu;
   for (const auto &per_cu : per_bfd->all_units)
     {

gdb/dwarf2/read.c

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 2a29b84..30ef69a 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -79,7 +79,6 @@
 #include "gdbsupport/function-view.h"
 #include <optional>
 #include "gdbsupport/underlying.h"
-#include "gdbsupport/hash_enum.h"
 #include "filename-seen-cache.h"
 #include "producer.h"
 #include <fcntl.h>
@@ -11873,8 +11872,7 @@ dwarf2_add_type_defn (struct field_info *fip, struct die_info *die,
 
 /* A convenience typedef that's used when finding the discriminant
    field for a variant part.  */
-typedef std::unordered_map<sect_offset, int, gdb::hash_enum<sect_offset>>
-  offset_map_type;
+typedef std::unordered_map<sect_offset, int> offset_map_type;
 
 /* Compute the discriminant range for a given variant.  OBSTACK is
    where the results will be stored.  VARIANT is the variant to

gdb/dwarf2/read.h

diff --git a/gdb/dwarf2/read.h b/gdb/dwarf2/read.h
index 6637483..e311309 100644
--- a/gdb/dwarf2/read.h
+++ b/gdb/dwarf2/read.h
@@ -29,7 +29,6 @@
 #include "dwarf2/section.h"
 #include "dwarf2/cu.h"
 #include "gdbsupport/gdb_obstack.h"
-#include "gdbsupport/hash_enum.h"
 #include "gdbsupport/function-view.h"
 #include "gdbsupport/packed.h"
 
@@ -555,8 +554,7 @@ struct dwarf2_per_bfd
 
   /* Mapping from abstract origin DIE to concrete DIEs that reference it as
      DW_AT_abstract_origin.  */
-  std::unordered_map<sect_offset, std::vector<sect_offset>,
-		     gdb::hash_enum<sect_offset>>
+  std::unordered_map<sect_offset, std::vector<sect_offset>>
     abstract_to_concrete;
 
   /* Current directory, captured at the moment that object this was

gdb/stap-probe.c

diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c
index 9558351..9a2ff92 100644
--- a/gdb/stap-probe.c
+++ b/gdb/stap-probe.c
@@ -38,7 +38,6 @@
 #include "elf-bfd.h"
 #include "expop.h"
 #include <unordered_map>
-#include "gdbsupport/hash_enum.h"
 
 #include <ctype.h>
 
@@ -435,8 +434,7 @@ typedef expr::operation_up binop_maker_ftype (expr::operation_up &&,
 					      expr::operation_up &&);
 /* Map from an expression opcode to a function that can create a
    binary operation of that type.  */
-static std::unordered_map<exp_opcode, binop_maker_ftype *,
-			  gdb::hash_enum<exp_opcode>> stap_maker_map;
+static std::unordered_map<exp_opcode, binop_maker_ftype *> stap_maker_map;
 
 /* Helper function to create a binary operation.  */
 static expr::operation_up

gdbsupport/hash_enum.h

diff --git a/gdbsupport/hash_enum.h b/gdbsupport/hash_enum.h
deleted file mode 100644
index 5ef0e15..0000000
--- a/gdbsupport/hash_enum.h
+++ /dev/null
@@ -1,45 +0,0 @@
-/* A hasher for enums.
-
-   Copyright (C) 2017-2024 Free Software Foundation, Inc.
-
-   This file is part of GDB.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 3 of the License, or
-   (at your option) any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
-
-#ifndef COMMON_HASH_ENUM_H
-#define COMMON_HASH_ENUM_H
-
-/* A hasher for enums, which was missing in C++11:
-    http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2148
-*/
-
-namespace gdb {
-
-/* Helper struct for hashing enum types.  */
-template<typename T>
-struct hash_enum
-{
-  typedef size_t result_type;
-  typedef T argument_type;
-
-  size_t operator() (T val) const noexcept
-  {
-    using underlying = typename std::underlying_type<T>::type;
-    return std::hash<underlying> () (static_cast<underlying> (val));
-  }
-};
-
-} /* namespace gdb */
-
-#endif /* COMMON_HASH_ENUM_H */