[backport 3.5.x] Remove __constant_wrapper from 3.5 release

[davebayer]

There are problems with __constant_wrapper, our weekly testing shows that gcc-10 even fails to parse the source code. I'd rather completely remove it from 3.5 release, since it's not even used anywhere.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Plan: Enterprise

Run ID: cad6f847-8849-4689-bdc2-b76024014d8a

📥 Commits

Reviewing files that changed from the base of the PR and between 3855b5a and d46b3d9.

📒 Files selected for processing (23)

• libcudacxx/include/cuda/std/__utility/constant_wrapper.h
• libcudacxx/include/cuda/std/utility
• libcudacxx/include/cuda/std/version
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/adl.compile.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/assign.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/binary_ops.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/call.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/comma.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/comp.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/convert.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/ctad.compile.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/cw.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/cw_fixed.array.ctor.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/cw_fixed.ctor.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/general.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/helpers.h
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/kernel_parameter.array.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/kernel_parameter.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/mem_ptr.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/pseudo_mutators.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/subscript.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/types.compile.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/unary_ops.pass.cpp

💤 Files with no reviewable changes (23)

• libcudacxx/include/cuda/std/utility
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/ctad.compile.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/cw.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/types.compile.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/kernel_parameter.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/kernel_parameter.array.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/pseudo_mutators.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/comma.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/cw_fixed.array.ctor.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/assign.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/mem_ptr.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/convert.pass.cpp
• libcudacxx/include/cuda/std/__utility/constant_wrapper.h
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/adl.compile.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/helpers.h
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/unary_ops.pass.cpp
• libcudacxx/include/cuda/std/version
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/binary_ops.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/general.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/subscript.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/call.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/comp.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/const.wrap.class/cw_fixed.ctor.pass.cpp

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📝 Walkthrough

Summary by CodeRabbit

• Breaking Changes

  • Removed constant-wrapper support from the CUDA standard utility library.
  • Constant-wrapper types, helpers, predefined instances, traits, and related operators are no longer available.
  • Removed the associated feature-test marker.

• Tests

  • Removed compile-time, runtime, CUDA kernel, and operator coverage for constant-wrapper functionality.

Walkthrough

The pull request removes the constant wrapper header, its public utility include, related version metadata, and the associated constant wrapper tests.

Changes

Constant wrapper removal

Layer / File(s)	Summary
Public surface cleanup libcudacxx/include/cuda/std/utility, libcudacxx/include/cuda/std/version	The utility header no longer includes constant_wrapper.h. The disabled __cccl_lib_constant_wrapper feature-test declaration and TODO were removed. The constant wrapper implementation and tests were deleted.

Suggested reviewers: pciolkosz

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

---

_{Comment @coderabbitai help to get the list of available commands.}

[github-actions]

⏱️ CCCL compile-time benchmark comparison: Public headers compile-time bench

Result: 2 regression row(s), 3 improvement row(s) above threshold.

Run	Value
Config	public-headers-gcc13
Baseline	origin/main
Preset	all-dev
Targets	cub.headers.base, thrust.cpp.cuda.headers.base, libcudacxx.test.public_headers
GPU / launch args	rtx2080 / --cuda 13.3 --host gcc13

Artifacts: reports and traces

Direct file processing

-f file-processing exclusive --sort total

🔴 Direct file processing — Regressions

Rank	Regression impact	Selected Δ	Baseline	Current	Event	Matched traces
1	0.334603	0.334603	19.923202	20.257805	Processing Header File: libcudacxx/include/cuda/__device/physical_device.h	94
2	0.204405	0.204405	7.598279	7.802684	Processing Header File: cub/cub/util_type.cuh	278

🟢 Direct file processing — Improvements

Rank	Improvement impact	Selected Δ	Baseline	Current	Event	Matched traces
1	0.989336	-0.989336	9.546088	8.556752	Processing Header File: libcudacxx/include/cuda/std/__cccl/prologue.h	548
2	0.542149	-0.542149	3.507896	2.965747	Processing Header File: libcudacxx/include/cuda/std/__cccl/epilogue.h	548
3	0.334162	-0.334162	2.894132	2.559970	Processing Header File: libcudacxx/include/cuda/std/__atomic/functions/cuda_ptx_generated.h	56

[github-actions]

🥳 CI Workflow Results

🟩 Finished in 4h 23m: Pass: 100%/115 | Total: 5d 17h | Max: 4h 22m | Hits: 42%/1802361

See results here.

[davebayer]

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