Remove tagged, tagged_pair and tagged_tuple, remove tuple/pair specializations

[Jedi18]

Fixes #5652

Proposed Changes

• Remove tagged, tagged_pair and tagged_tuple (and related tests)
• Change partition_copy and sort_by_key to use appropriate return types instead of tagged_tuple and tagged_pair
• Remove tuple/pair specializations from local_algorithm_result and algorithm_result_helper

[StellarBot]

Performance test report

HPX Performance

Comparison

BENCHMARK	NO-EXECUTOR
Future Overhead - Create Thread Hierarchical - Latch	(=)

Info

Property	Before	After
HPX Datetime	2021-11-11T08:14:57+00:00	2021-11-17T05:19:21+00:00
HPX Commit	96a2e4b	2397a6e
Datetime	2021-11-11T09:28:13.071121+01:00	2021-11-17T06:33:14.287827+01:00
Compiler	/apps/daint/SSL/HPX/packages/llvm-11.0.0/bin/clang++ 11.0.0	/apps/daint/SSL/HPX/packages/llvm-11.0.0/bin/clang++ 11.0.0
Clustername	daint	daint
Hostname	nid00006	nid00101
Envfile

Comparison

BENCHMARK	FORK_JOIN_EXECUTOR_DEFAULT_FORK_JOIN_POLICY_ALLOCATOR	PARALLEL_EXECUTOR_DEFAULT_PARALLEL_POLICY_ALLOCATOR	SCHEDULER_EXECUTOR_DEFAULT_SCHEDULER_EXECUTOR_ALLOCATOR
Stream Benchmark - Add	-	(=)	(=)
Stream Benchmark - Scale	(=)	(=)	(=)
Stream Benchmark - Triad	(=)	(=)	(=)
Stream Benchmark - Copy	(=)	=	(=)

Info

Property	Before	After
HPX Datetime	2021-11-10T19:14:21+00:00	2021-11-17T05:19:21+00:00
HPX Commit	71d8dbe	2397a6e
Datetime	2021-11-10T20:28:18.266961+01:00	2021-11-17T06:33:29.760387+01:00
Compiler	/apps/daint/SSL/HPX/packages/llvm-11.0.0/bin/clang++ 11.0.0	/apps/daint/SSL/HPX/packages/llvm-11.0.0/bin/clang++ 11.0.0
Clustername	daint	daint
Hostname	nid00120	nid00101
Envfile

Explanation of Symbols

Symbol	MEANING
=	No performance change (confidence interval within ±1%)
(=)	Probably no performance change (confidence interval within ±2%)
(+)/(-)	Very small performance improvement/degradation (≤1%)
+/-	Small performance improvement/degradation (≤5%)
++/--	Large performance improvement/degradation (≤10%)
+++/---	Very large performance improvement/degradation (>10%)
?	Probably no change, but quite large uncertainty (confidence interval with ±5%)
??	Unclear result, very large uncertainty (±10%)
???	Something unexpected…

[hkaiser]

LGTM, thanks!

[hkaiser]

bors merge

[bors]

Build succeeded:

• Bors