[libcu++] Implement tuple-like constructors for tuple

[miscco]

This refactors the constructor constraints for cuda::std::tuple and implements the new tuple-like constructors

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[miscco]

/ok to test

[miscco]

/ok to test

[miscco]

/ok to test

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📝 Walkthrough

important:

Walkthrough

Refactors tuple constraint evaluation to consteval checkers, adds forward-detection traits for pair/tuple/subrange, rebases tuple-like detection, updates tuple constructors/leaf/tuple_cat to use new constraint aliases, and adds test support types plus comprehensive tuple conversion tests.

Changes

Tuple construction and constraint machinery refactor

Layer / File(s)	Summary
Type detection traits for CUDA std types libcudacxx/include/cuda/std/__fwd/pair.h, libcudacxx/include/cuda/std/__fwd/subrange.h, libcudacxx/include/cuda/std/__fwd/tuple.h	Forward-declaration variable-template traits __is_cuda_std_pair, __is_cuda_std_tuple, and __is_cuda_std_ranges_subrange_v added to enable compile-time identification of CUDA std types.
Tuple-like detection trait rename and use libcudacxx/include/cuda/std/__tuple_dir/tuple_like.h	Rebases internal tuple-like detection to __tuple_like_ext, updates its specializations for tuple-like types, and rewires __tuple_like/__pair_like to use it.
Constraint machinery rewrite libcudacxx/include/cuda/std/__tuple_dir/tuple_constraints.h	Replaces predicate-and-nested-template __tuple_constraints with a consteval-checker-based _TupleConstructorTraits computation and helpers; updates __tuple_like_with_size to use __tuple_like and refreshes comparison derivations.
Tuple class constructor refactoring libcudacxx/include/cuda/std/__tuple_dir/tuple.h	Adds _Constraints alias and rewrites tuple constructors to use nested _Constraints construction traits for SFINAE and noexcept; expands tuple-like converting overloads across reference categories.
Tuple leaf default constructor and element extraction libcudacxx/include/cuda/std/__tuple_dir/tuple_leaf.h	Splits __tuple_impl default ctor into implicit/explicit SFINAE overloads, shifts noexcept to __nothrow_constructible, and uses cuda::std::get on forwarded tuples for element initialization (allocator and non-allocator forms).
Tuple cat return-type update libcudacxx/include/cuda/std/__tuple_dir/tuple_cat.h	Updates __tuple_cat_return specializations to use __tuple_like_ext for tuple-like detection in return-type computation.
Test support infrastructure libcudacxx/test/support/copy_move_types.h	Adds a test header providing many probe types modeling constrained/asymmetric copy/move/convert/allocator behaviors, tracing counters for constructor/assignment selection, and implicit-constructibility helpers.
Tuple construction tests libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/*, libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.traits/trivially_copyable.pass.cpp	Adds multiple test translation units validating tuple construction from pair (const/non-const), tuple-to-tuple conversions (const/non-const copy/move), explicitness/convertibility rules, and traced constructor selection; updates an existing explicit-conversion test and a trivially-copyable expectation.

• Suggested reviewers:
  • ericniebler
  • alliepiper
  • davebayer

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Actionable comments posted: 4

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📥 Commits

Reviewing files that changed from the base of the PR and between 589097d and 93d612c.

📒 Files selected for processing (16)

• libcudacxx/include/cuda/std/__fwd/pair.h
• libcudacxx/include/cuda/std/__fwd/subrange.h
• libcudacxx/include/cuda/std/__fwd/tuple.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_cat.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_constraints.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_leaf.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_like.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_like_ext.h
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR31384.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/const_move_pair.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_const_move.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_non_const_copy.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/non_const_pair.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.traits/trivially_copyable.pass.cpp
• libcudacxx/test/support/copy_move_types.h

💤 Files with no reviewable changes (1)

• libcudacxx/include/cuda/std/__tuple_dir/tuple_like_ext.h

[coderabbitai]

🧹 Nitpick comments (2)

libcudacxx/include/cuda/std/__fwd/pair.h (1)

43-47: 💤 Low value

suggestion: Consider renaming to __is_cuda_std_pair_v for consistency with __is_tuple_of_iterator_references_v (line 40 of __fwd/tuple.h). The codebase has mixed patterns (__tuple_like_ext lacks _v, but iterator-references trait has it); standardizing on _v for boolean variable-template detection traits would improve uniformity.

libcudacxx/include/cuda/std/__fwd/tuple.h (1)

42-46: 💤 Low value

suggestion: Consider renaming to __is_cuda_std_tuple_v for consistency with __is_tuple_of_iterator_references_v at line 40 in this same file. Both are boolean variable-template detection traits; matching naming conventions within the same header improves readability.

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 31a7c568-a91d-424a-942f-65730dfe1952

📥 Commits

Reviewing files that changed from the base of the PR and between 93d612c and f46bbc9.

📒 Files selected for processing (16)

• libcudacxx/include/cuda/std/__fwd/pair.h
• libcudacxx/include/cuda/std/__fwd/subrange.h
• libcudacxx/include/cuda/std/__fwd/tuple.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_cat.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_constraints.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_leaf.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_like.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_like_ext.h
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR31384.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/const_move_pair.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_const_move.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_non_const_copy.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/non_const_pair.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.traits/trivially_copyable.pass.cpp
• libcudacxx/test/support/copy_move_types.h

💤 Files with no reviewable changes (1)

• libcudacxx/include/cuda/std/__tuple_dir/tuple_like_ext.h

[coderabbitai]

Actionable comments posted: 2

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Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 5671e078-4c87-47a1-9dcd-94832367d4ec

📥 Commits

Reviewing files that changed from the base of the PR and between f46bbc9 and 21aa1e3.

📒 Files selected for processing (16)

• libcudacxx/include/cuda/std/__fwd/pair.h
• libcudacxx/include/cuda/std/__fwd/subrange.h
• libcudacxx/include/cuda/std/__fwd/tuple.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_cat.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_constraints.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_leaf.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_like.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_like_ext.h
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR31384.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/const_move_pair.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_const_move.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_non_const_copy.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/non_const_pair.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.traits/trivially_copyable.pass.cpp
• libcudacxx/test/support/copy_move_types.h

💤 Files with no reviewable changes (1)

• libcudacxx/include/cuda/std/__tuple_dir/tuple_like_ext.h

✅ Files skipped from review due to trivial changes (1)

• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR31384.pass.cpp

[coderabbitai]

🧹 Nitpick comments (2)

libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_const_move.pass.cpp (1)

116-131: ⚡ Quick win

suggestion: Lines 116-131 disable these constraint cases for every compiler via #if 0; gate them only for the compiler/version that actually segfaults so other toolchains keep this coverage.

libcudacxx/include/cuda/std/__fwd/subrange.h (1)

56-56: 💤 Low value

suggestion: Naming inconsistency with other detection traits. __is_cuda_std_ranges_subrange_v has a _v suffix, but __is_cuda_std_pair and __is_cuda_std_tuple do not. For internal consistency, either add _v to all three or remove it from this one.

Also applies to: 59-59

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Review profile: CHILL

Plan: Enterprise

Run ID: aff077ac-4ceb-498f-9dbe-7ce4a83c0012

📥 Commits

Reviewing files that changed from the base of the PR and between ce8a059 and f423ab2.

📒 Files selected for processing (16)

• libcudacxx/include/cuda/std/__fwd/pair.h
• libcudacxx/include/cuda/std/__fwd/subrange.h
• libcudacxx/include/cuda/std/__fwd/tuple.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_cat.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_constraints.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_leaf.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_like.h
• libcudacxx/include/cuda/std/__tuple_dir/tuple_like_ext.h
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR31384.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/const_move_pair.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_const_move.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/convert_non_const_copy.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.cnstr/non_const_pair.pass.cpp
• libcudacxx/test/libcudacxx/std/utilities/tuple/tuple.tuple/tuple.traits/trivially_copyable.pass.cpp
• libcudacxx/test/support/copy_move_types.h

💤 Files with no reviewable changes (1)

• libcudacxx/include/cuda/std/__tuple_dir/tuple_like_ext.h

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