diff mbox series

Remove std::hash specialization

Message ID 20250313202853.2769260-1-tom@tromey.com
State New
Headers
Series Remove std::hash specialization |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gdb_build--master-aarch64 success Build passed
linaro-tcwg-bot/tcwg_gdb_build--master-arm success Build passed
linaro-tcwg-bot/tcwg_gdb_check--master-arm success Test passed
linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 success Test passed

Commit Message

Tom Tromey March 13, 2025, 8:28 p.m. UTC 
  C++11 initially omitted specialization of std::hash for enumeration
types, but this was rectified in LWG issue 2148.  This patch removes a
redundant specialization.  Tested by rebuilding.
---
 gdb/dictionary.c | 17 -----------------
 1 file changed, 17 deletions(-)

Comments

Simon Marchi March 13, 2025, 11:30 p.m. UTC | #1 
On 2025-03-13 16:28, Tom Tromey wrote:
> C++11 initially omitted specialization of std::hash for enumeration
> types, but this was rectified in LWG issue 2148.  This patch removes a
> redundant specialization.  Tested by rebuilding.

Does this work with the oldest compiler we want to support (I don't
recall which version it is now)?

If so, it seems like a trivial change.

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

Simon
Tom Tromey March 14, 2025, 2:31 p.m. UTC | #2 
>>>>> "Simon" == Simon Marchi <simark@simark.ca> writes:

Simon> On 2025-03-13 16:28, Tom Tromey wrote:
>> C++11 initially omitted specialization of std::hash for enumeration
>> types, but this was rectified in LWG issue 2148.  This patch removes a
>> redundant specialization.  Tested by rebuilding.

Simon> Does this work with the oldest compiler we want to support (I don't
Simon> recall which version it is now)?

I don't know.  However since gdb relies on C++17 and this was a
11/14-ish era feature (I believe), I think we should go ahead anyway.
Worst case, we will get a report and then I can back out the patch.

Tom
Simon Marchi March 14, 2025, 4:04 p.m. UTC | #3 
On 3/14/25 10:31 AM, Tom Tromey wrote:
>>>>>> "Simon" == Simon Marchi <simark@simark.ca> writes:
> 
> Simon> On 2025-03-13 16:28, Tom Tromey wrote:
>>> C++11 initially omitted specialization of std::hash for enumeration
>>> types, but this was rectified in LWG issue 2148.  This patch removes a
>>> redundant specialization.  Tested by rebuilding.
> 
> Simon> Does this work with the oldest compiler we want to support (I don't
> Simon> recall which version it is now)?
> 
> I don't know.  However since gdb relies on C++17 and this was a
> 11/14-ish era feature (I believe), I think we should go ahead anyway.
> Worst case, we will get a report and then I can back out the patch.
> 
> Tom

Ah nevermind, in my mind for a moment I thought we were still on C++11.

There is already a precedent:

https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=8675d15227529517e0a7e78e1524ad9cc76afc14

So:

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

Simon
diff mbox series

Patch

diff --git a/gdb/dictionary.c b/gdb/dictionary.c
index 6925ad4d46c..f617b8f967f 100644
--- a/gdb/dictionary.c
+++ b/gdb/dictionary.c
@@ -915,23 +915,6 @@  struct multidictionary
   unsigned short n_allocated_dictionaries;
 };
 
-/* A hasher for enum language.  Injecting this into std is a convenience
-   when using unordered_map with C++11.  */
-
-namespace std
-{
-  template<> struct hash<enum language>
-  {
-    typedef enum language argument_type;
-    typedef std::size_t result_type;
-
-    result_type operator() (const argument_type &l) const noexcept
-    {
-      return static_cast<result_type> (l);
-    }
-  };
-} /* namespace std */
-
 /* A helper function to collate symbols on the pending list by language.  */
 
 static std::unordered_map<enum language, std::vector<symbol *>>