[libcu++] Fix nvcc picking up hidden friends on windows

[davebayer]

#10687 silently broke main, because nvcc on windows seem to pick up hidden friends for other classes as well during host stubs generation. This PR fixes that problem by further constraining constant_wrapper's operators

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 2a22e5d3-bd79-4718-b6e3-9a83e59ca645

📥 Commits

Reviewing files that changed from the base of the PR and between 269cde9 and 4895477.

📒 Files selected for processing (1)

• libcudacxx/include/cuda/std/__utility/constant_wrapper.h

🚧 Files skipped from review as they are similar to previous changes (1)

• libcudacxx/include/cuda/std/__utility/constant_wrapper.h

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📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Improved operator constraint handling for constant wrapper values.
  • Ensured supported binary operations require valid constexpr operands.
  • Preserved restrictions for logical operators while maintaining existing behavior for unaffected operations.

Walkthrough

Changes

The constant-wrapper implementation adds wrapper-type detection and applies wrapper-participation constraints across unary, mutator, binary, logical, comparison, comma, and pointer-to-member operators.

Constant-wrapper operator constraints

Layer / File(s)	Summary
Wrapper detection and unary constraints libcudacxx/include/cuda/std/__utility/constant_wrapper.h	Adds __is_cuda_std_constant_wrapper_v. Unary and increment/decrement overloads require wrapper operands and constexpr parameters.
Binary operator constraints libcudacxx/include/cuda/std/__utility/constant_wrapper.h	Arithmetic, shift, bitwise, and logical-and overloads require wrapper participation. Binary operands remain constrained as constexpr parameters, and the non-boolean restriction for && remains.
Comparison and special operator constraints libcudacxx/include/cuda/std/__utility/constant_wrapper.h	Spaceship, relational comparison, comma, and pointer-to-member constraints require wrapper participation alongside existing constexpr requirements.

Possibly related PRs

• NVIDIA/cccl#10687: Both changes update constant_wrapper.h operator detection and constraints.

Suggested reviewers: jrhemstad, fbusato

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[coderabbitai]

Actionable comments posted: 2

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ℹ️ Review info

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

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Run ID: 7b43098a-1f59-4289-b478-64af3ff9ef5a

📥 Commits

Reviewing files that changed from the base of the PR and between 8b0b7eb and 269cde9.

📒 Files selected for processing (3)

• ci/matrix.yaml
• libcudacxx/include/cuda/__execution/output_ordering.h
• libcudacxx/include/cuda/std/__utility/constant_wrapper.h

[github-actions]

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

Result: 1 regression row(s), 5 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

TU total compilation

-f total-compilation inclusive --sort total

🟢 TU total compilation — Improvements

Rank	Improvement impact	Selected Δ	Baseline	Current	Event	Matched traces
1	4.223102	-4.223102	19.737656	15.514554	Total Compilation Time: cuda/execution	1

Direct file processing

-f file-processing exclusive --sort total

🔴 Direct file processing — Regressions

Rank	Regression impact	Selected Δ	Baseline	Current	Event	Matched traces
1	1.088121	1.088121	19.679740	20.767861	Processing Header File: libcudacxx/include/cuda/__device/physical_device.h	94

🟢 Direct file processing — Improvements

Rank	Improvement impact	Selected Δ	Baseline	Current	Event	Matched traces
1	1.149575	-1.149575	9.658821	8.509246	Processing Header File: libcudacxx/include/cuda/std/__cccl/prologue.h	550
2	0.530647	-0.530647	2.939147	2.408500	Processing Header File: libcudacxx/include/cuda/std/__atomic/functions/cuda_ptx_generated.h	57
3	0.283896	-0.283896	3.447467	3.163571	Processing Header File: libcudacxx/include/cuda/std/__cccl/epilogue.h	550
4	0.239656	-0.239656	11.033785	10.794129	Processing Header File: libcudacxx/include/cuda/std/__iterator/concepts.h	437