bugprone-move-forwarding-reference

[Jacobfaib]

Description

closes

Checklist

• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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📒 Files selected for processing (2)

• .clang-tidy
• thrust/thrust/detail/allocator_aware_execution_policy.h

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• .clang-tidy

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Summary

This PR fixes a code correctness issue related to the improper use of std::move with forwarding references and enables the corresponding clang-tidy diagnostic to prevent similar issues in the future.

Changes Made

.clang-tidy

• Enabled the bugprone-move-forwarding-reference clang-tidy check by including it in the enabled checks list without exclusion. This diagnostic detects cases where std::move is incorrectly used with forwarding references, which can lead to incorrect semantics.

thrust/thrust/detail/allocator_aware_execution_policy.h

• Updated the include directive to use cuda/std/__utility/forward.h instead of cuda/std/__utility/move.h
• Fixed the rvalue reference overload of operator()(Allocator&&) to use cuda::std::forward<Allocator>(alloc) instead of cuda::std::move(alloc). This is the correct pattern for forwarding references, as it properly preserves the value category of the original argument (whether it's an lvalue or rvalue).

Rationale

When a template parameter is deduced as a forwarding reference (e.g., Allocator&& where Allocator is a template parameter), using std::forward instead of std::move ensures proper value category semantics. The std::move utility unconditionally casts to an rvalue reference, which can lead to unexpected behavior when the original argument is an lvalue reference, whereas std::forward correctly preserves the original reference type.

Walkthrough

allocator_aware_execution_policy's rvalue operator()(Allocator&&) previously called cuda::std::move(alloc) on a forwarding reference, which is incorrect. The fix replaces move with cuda::std::forward<Allocator> and swaps the move.h include for forward.h. The -bugprone-move-forwarding-reference suppression is then removed from .clang-tidy.

Changes

Forwarding-reference fix and lint re-enablement

Layer / File(s)	Summary
Switch allocator operator to perfect-forward thrust/thrust/detail/allocator_aware_execution_policy.h	Includes forward.h instead of move.h; changes operator()(Allocator&&) body from cuda::std::move(alloc) to cuda::std::forward<Allocator>(alloc).
Re-enable clang-tidy check .clang-tidy	Removes -bugprone-move-forwarding-reference from the disabled checks list now that the triggering code is fixed.

Possibly related PRs

• NVIDIA/cccl#9467: Modifies .clang-tidy bugprone-* configuration — enables bugprone-* broadly and selectively disables specific checks, directly overlapping with this PR's removal of the bugprone-move-forwarding-reference suppression.

Suggested reviewers

• bernhardmgruber

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