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[binutils-gdb] Add gdb::hash_enum
- From: Pedro Alves <palves at sourceware dot org>
- To: gdb-cvs at sourceware dot org
- Date: 8 Dec 2017 23:40:27 -0000
- Subject: [binutils-gdb] Add gdb::hash_enum
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=e5fa6583a7b1e5e0e0f33a4964a1f271e189cf35
commit e5fa6583a7b1e5e0e0f33a4964a1f271e189cf35
Author: Pedro Alves <palves@redhat.com>
Date: Fri Dec 8 22:44:12 2017 +0000
Add gdb::hash_enum
The DWARF-5 .debug_names consumer patch will want to use an
std::unordered_map with an enum as key type, like:
std::unordered_map<sect_offset, dwarf2_per_cu_data*>
That doesn't work in C++11 in non-recent compilers due to a language
defect:
http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#2148
~~~
In file included from /usr/include/c++/5.3.1/bits/hashtable.h:35:0,
from /usr/include/c++/5.3.1/unordered_set:47,
from src/gdb/dwarf2read.c:79:
/usr/include/c++/5.3.1/bits/hashtable_policy.h: In instantiation of â??struct std::__detail::__is_noexcept_hash<sect_offset, std::hash<sect_offset> >â??:
/usr/include/c++/5.3.1/type_traits:137:12: required from â??struct std::__and_<std::__is_fast_hash<std::hash<sect_offset> >, std::__detail::__is_noexcept_hash<sect_offset, std::hash<sect_offset> > >â??
/usr/include/c++/5.3.1/type_traits:148:38: required from â??struct std::__not_<std::__and_<std::__is_fast_hash<std::hash<sect_offset> >, std::__detail::__is_noexcept_hash<sect_offset, std::hash<sect_offset> > > >â??
/usr/include/c++/5.3.1/bits/unordered_map.h:100:66: required from â??class std::unordered_map<sect_offset, dwarf2_per_cu_data*>â??
src/gdb/dwarf2read.c:3260:30: required from here
/usr/include/c++/5.3.1/bits/hashtable_policy.h:85:34: error: no match for call to â??(const std::hash<sect_offset>) (const sect_offset&)â??
noexcept(declval<const _Hash&>()(declval<const _Key&>()))>
^
In file included from /usr/include/c++/5.3.1/bits/move.h:57:0,
from /usr/include/c++/5.3.1/bits/stl_pair.h:59,
from /usr/include/c++/5.3.1/bits/stl_algobase.h:64,
from /usr/include/c++/5.3.1/bits/char_traits.h:39,
from /usr/include/c++/5.3.1/string:40,
from /home/pedro/gdb/mygit/src/gdb/common/common-utils.h:23,
from /home/pedro/gdb/mygit/src/gdb/common/common-defs.h:78,
from /home/pedro/gdb/mygit/src/gdb/defs.h:28,
from /home/pedro/gdb/mygit/src/gdb/dwarf2read.c:31:
~~~
This commits adds a helper replacement.
gdb/ChangeLog:
2017-12-08 Pedro Alves <palves@redhat.com>
* common/hash_enum.h: New file.
Diff:
---
gdb/ChangeLog | 4 ++++
gdb/common/hash_enum.h | 45 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 49 insertions(+)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 5d596f0..09cafd0 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,7 @@
+2017-12-08 Pedro Alves <palves@redhat.com>
+
+ * common/hash_enum.h: New file.
+
2017-12-08 Jan Kratochvil <jan.kratochvil@redhat.com>
* dwarf2read.c (create_cu_from_index_list): New from ...
diff --git a/gdb/common/hash_enum.h b/gdb/common/hash_enum.h
new file mode 100644
index 0000000..0ea3221
--- /dev/null
+++ b/gdb/common/hash_enum.h
@@ -0,0 +1,45 @@
+/* A hasher for enums.
+
+ Copyright (C) 2017 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 */