Clean up stdexec-only paths and update affected tests

[guptapratykshh]

Proposed Changes

• removedHPX_HAVE_STDEXECguarded cleanup paths and kept the stdexec-only implementation as the single active path
• update the affected execution, execution_base, executor, algorithm, async MPI/CUDA, and synchronization tests to match the unified stdexec-only code path
• cleared up related CMake/stdexec configuration so the build reflects the same single-path setup consistently

Any background context you want to provide?

Checklist

Not all points below apply to all pull requests.

• I have added a new feature and have added tests to go along with it.
• I have fixed a bug and have added a regression test.
• I have added a test using random numbers; I have made sure it uses a seed, and that random numbers generated are valid inputs for the tests.

[StellarBot]

Can one of the admins verify this patch?

[hkaiser]

@isidorostsa Please have a look

[hkaiser]

BTW, how does this relate to #6708? Does this PR superseds it?

[hkaiser]

@guptapratykshh thanks for working on this. Could you please proactively keep an eye on the CI results. Currently there seem to be some compilation issues with this PR.

[guptapratykshh]

BTW, how does this relate to #6708? Does this PR superseds it?

this PR is a narrower follow up in the same direction as #6708, updated on top of the current master rather than a wholesale replacement for it. It keeps the stdexec-only cleanup goal, but its scope here is mainly removing the remaining dead internal paths and fixing the resulting test issues while preserving backward compatibility.

[hkaiser]

BTW, how does this relate to #6708? Does this PR superseds it?

this PR is a narrower follow up in the same direction as #6708, updated on top of the current master rather than a wholesale replacement for it. It keeps the stdexec-only cleanup goal, but its scope here is mainly removing the remaining dead internal paths and fixing the resulting test issues while preserving backward compatibility.

Thanks for the explanations. Do we still need #6708? What does it have in addition to your PR?

[guptapratykshh]

BTW, how does this relate to #6708? Does this PR superseds it?

this PR is a narrower follow up in the same direction as #6708, updated on top of the current master rather than a wholesale replacement for it. It keeps the stdexec-only cleanup goal, but its scope here is mainly removing the remaining dead internal paths and fixing the resulting test issues while preserving backward compatibility.

Thanks for the explanations. Do we still need #6708? What does it have in addition to your PR?

after merging #6708 into my branch and updating it to work with current master, I do not think we still need #6708 as separate PR

[hkaiser]

Thanks for the explanations. Do we still need #6708? What does it have in addition to your PR?

after merging #6708 into my branch and updating it to work with current master, I do not think we still need #6708 as separate PR

Ok, please let me know once you think that we can close the other PR.

[isidorostsa]

Thank you for taking on this task! Removing old senders would be helpful

To make it possible to review this please contain unnecessary or pedantic edits as much as possible.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

This PR removes the remaining HPX_HAVE_STDEXEC-guarded legacy execution paths, making the stdexec-based implementation the single supported code path, and updates tests/build configuration accordingly.

Changes:

• Removed non-stdexec implementations and preprocessor guards across execution/execution_base and related algorithms/queries.
• Updated unit/performance tests and examples to match stdexec semantics (e.g., sender/receiver concepts, env-based queries, adaptor usage).
• Adjusted CMake/stdexec integration (stdexec required, FetchContent patching, compiler-specific workarounds and test selection).

Reviewed changes

Copilot reviewed 147 out of 167 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
libs/core/execution_base/tests/unit/basic_schedule.cpp	Updates scheduler/sender test scaffolding to stdexec sender/scheduler conventions.
libs/core/execution_base/tests/unit/basic_operation_state.cpp	Removes non-stdexec assertions; adds Clang deprecation-warning suppression.
libs/core/execution_base/tests/unit/any_sender.cpp	Aligns sender concept checks with stdexec; adds Clang deprecation-warning suppression.
libs/core/execution_base/tests/unit/CMakeLists.txt	Disables execution_base unit tests for Clang/AppleClang builds.
libs/core/execution_base/tests/include/coroutine_task.hpp	Removes legacy await_suspend path; standardizes on stdexec continuation handle access.
libs/core/execution_base/include/hpx/execution_base/traits/coroutine_traits.hpp	Makes stdexec coroutine trait checks unconditional.
libs/core/execution_base/include/hpx/execution_base/this_thread.hpp	Switches to stdexec-forward include and re-exports this_thread + stdexec query.
libs/core/execution_base/include/hpx/execution_base/stdexec_forward.hpp	Centralizes stdexec includes, warning suppression, and forwards additional CPOs/utilities.
libs/core/execution_base/include/hpx/execution_base/sender.hpp	Removes non-stdexec sender CPOs/traits implementation; relies on stdexec forward.
libs/core/execution_base/include/hpx/execution_base/operation_state.hpp	Removes non-stdexec operation_state/start implementation; relies on stdexec forward.
libs/core/execution_base/include/hpx/execution_base/coroutine_utils.hpp	Removes non-stdexec coroutine sender-awaitable utilities declarations.
libs/core/execution_base/include/hpx/execution_base/completion_scheduler.hpp	Drops legacy completion_scheduler implementation; uses stdexec-based concepts/CPOs.
libs/core/execution_base/include/hpx/execution_base/any_sender.hpp	Updates type-erased senders/receivers to stdexec sender/receiver concepts and signatures.
libs/core/execution/tests/unit/forwarding_sender_query.cpp	Unifies forwarding query tests to stdexec forwarding_query.
libs/core/execution/tests/unit/forwarding_scheduler_query.cpp	Unifies forwarding scheduler query tests to stdexec forwarding_query.
libs/core/execution/tests/unit/forwarding_env_query.cpp	Unifies forwarding env query tests to stdexec forwarding_query.
libs/core/execution/tests/unit/environment_queries.cpp	Updates receiver/env query customization to stdexec-style members.
libs/core/execution/tests/unit/algorithm_transfer_when_all.cpp	Updates completion scheduler query usage and start invocation; adds Clang deprecation suppression.
libs/core/execution/tests/unit/algorithm_transfer.cpp	Updates env completion scheduler query and sender checks; adds Clang deprecation suppression.
libs/core/execution/tests/unit/algorithm_sync_wait_with_variant.cpp	Removes legacy pipeline form; uses direct sync_wait_with_variant calls.
libs/core/execution/tests/unit/algorithm_sync_wait.cpp	Removes legacy pipeline form; uses direct sync_wait calls.
libs/core/execution/tests/unit/algorithm_start_detached.cpp	Removes legacy operator| test block (non-stdexec-only behavior).
libs/core/execution/tests/unit/algorithm_let_value.cpp	Normalizes sender-in-env checks to stdexec is_sender_in_v.
libs/core/execution/tests/unit/algorithm_let_stopped.cpp	Normalizes sender-in-env checks and error-type expectations to stdexec behavior.
libs/core/execution/tests/unit/algorithm_let_error.cpp	Normalizes sender-in-env checks and value-type expectations to stdexec behavior.
libs/core/execution/tests/unit/algorithm_just_stopped.cpp	Removes redundant stdexec guards; matches stdexec error-type behavior.
libs/core/execution/tests/unit/algorithm_just_error.cpp	Removes redundant stdexec guards; matches stdexec error-type behavior.
libs/core/execution/tests/unit/algorithm_just.cpp	Removes redundant stdexec guards; aligns value/error type expectations with stdexec.
libs/core/execution/tests/unit/algorithm_execute.cpp	Unifies execute test to stdexec-only sender model; adds Clang deprecation suppression.
libs/core/execution/tests/unit/algorithm_as_sender.cpp	Normalizes sender-in-env checks to stdexec is_sender_in_v.
libs/core/execution/tests/unit/CMakeLists.txt	Disables execution unit tests for Clang/AppleClang builds.
libs/core/execution/src/run_loop.cpp	Removes legacy run_loop intrusive_ptr refcounting (non-stdexec-only).
libs/core/execution/include/hpx/execution/queries/read.hpp	Removes legacy read query sender implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/queries/get_stop_token.hpp	Removes legacy get_stop_token implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/queries/get_scheduler.hpp	Removes legacy get_scheduler/forward_progress implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/queries/get_delegatee_scheduler.hpp	Removes legacy get_delegatee_scheduler implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/queries/get_allocator.hpp	Removes legacy get_allocator implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/algorithms/when_all_vector.hpp	Switches to stdexec-forward header and stdexec completion signature utilities.
libs/core/execution/include/hpx/execution/algorithms/transfer_just.hpp	Removes legacy transfer_just implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/algorithms/transfer.hpp	Removes legacy transfer implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/algorithms/then.hpp	Removes legacy then implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/algorithms/keep_future.hpp	Migrates sender/op_state customization to member connect/start style.
libs/core/execution/include/hpx/execution/algorithms/just.hpp	Removes legacy just/just_error/just_stopped implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/algorithms/execute.hpp	Removes legacy execute implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/algorithms/ensure_started.hpp	Removes legacy ensure_started implementation (non-stdexec-only).
libs/core/execution/include/hpx/execution/algorithms/detail/partial_algorithm.hpp	Uses env-based completion scheduler query unconditionally.
libs/core/execution/include/hpx/execution/algorithms/bulk.hpp	Converts bulk sender/receiver to stdexec-only concepts/env/query patterns.
libs/core/execution/include/hpx/execution/algorithms/as_sender.hpp	Migrates as_sender sender/op_state customization to member connect/start style.
libs/core/execution/CMakeLists.txt	Removes legacy headers/sources from build; drops run_loop.cpp from sources.
libs/core/async_mpi/tests/unit/mpi_ring_async_executor.cpp	Removes HPX_HAVE_STDEXEC guard around MPI test execution.
libs/core/async_mpi/tests/unit/algorithm_transform_mpi.cpp	Removes HPX_HAVE_STDEXEC guard around MPI test execution.
libs/core/async_mpi/include/hpx/async_mpi/transform_mpi.hpp	Updates sender/receiver concepts and completion signatures to stdexec-only.
libs/core/async_cuda/tests/unit/transform_stream.cu	Replaces transfer with continues_on for context handoff back to HPX scheduler.
libs/core/async_cuda/tests/unit/cuda_multi_device_polling.cpp	Fixes author name encoding in header comment.
libs/core/async_cuda/tests/performance/synchronize.cu	Replaces pipeline `
libs/core/async_cuda/src/cuda_future.cpp	Fixes author name encoding in header comment.
libs/core/async_cuda/src/cuda_event_callback.cpp	Fixes author name encoding in header comment.
libs/core/async_cuda/include/hpx/async_cuda/transform_stream.hpp	Migrates to stdexec-only receiver/sender model (member ops, env, completion signatures).
libs/core/algorithms/tests/unit/container_algorithms/adjacentdifference_range_sender.cpp	Removes legacy pipeline `
libs/core/algorithms/tests/unit/container_algorithms/CMakeLists.txt	Removes specific sender tests on Clang/AppleClang.
libs/core/algorithms/tests/unit/algorithms/unique_tests.hpp	Makes sender test helpers unconditional (stdexec-only).
libs/core/algorithms/tests/unit/algorithms/uninitialized_value_constructn_sender.cpp	Reduces tested execution policy combinations for sender tests.
libs/core/algorithms/tests/unit/algorithms/uninitialized_value_construct_tests.hpp	Makes sender test helpers unconditional; adds assertions on "returned_from_algorithm".
libs/core/algorithms/tests/unit/algorithms/uninitialized_value_construct_sender.cpp	Reduces tested execution policy combinations for sender tests.
libs/core/algorithms/tests/unit/algorithms/uninitialized_relocaten_sender.cpp	Reduces tested execution policy combinations for sender tests.
libs/core/algorithms/tests/unit/algorithms/uninitialized_relocate_sender.cpp	Reduces tested execution policy combinations for sender tests.
libs/core/algorithms/tests/unit/algorithms/uninitialized_relocate_backward_sender.cpp	Reduces tested execution policy combinations for sender tests.
libs/core/algorithms/tests/unit/algorithms/uninitialized_moven_sender.cpp	Makes sender test helpers unconditional; reduces tested execution policy combinations.
libs/core/algorithms/tests/unit/algorithms/uninitialized_move_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/uninitialized_move_sender.cpp	Reduces tested execution policy combinations for sender tests.
libs/core/algorithms/tests/unit/algorithms/uninitialized_filln_sender.cpp	Makes sender test helpers unconditional; reduces tested execution policy combinations.
libs/core/algorithms/tests/unit/algorithms/uninitialized_fill_sender.cpp	Makes sender test helpers unconditional; reduces tested execution policy combinations.
libs/core/algorithms/tests/unit/algorithms/uninitialized_default_constructn_sender.cpp	Makes sender test helpers unconditional; reduces tested execution policy combinations.
libs/core/algorithms/tests/unit/algorithms/uninitialized_default_construct_tests.hpp	Makes sender test helpers unconditional; adds assertions on "returned_from_algorithm".
libs/core/algorithms/tests/unit/algorithms/uninitialized_default_construct_sender.cpp	Reduces tested execution policy combinations for sender tests.
libs/core/algorithms/tests/unit/algorithms/uninitialized_copyn_sender.cpp	Makes sender test helpers unconditional; reduces tested execution policy combinations.
libs/core/algorithms/tests/unit/algorithms/uninitialized_copy_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/transform_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/transform_reduce_binary_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/transform_binary_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/transform_binary2_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/remove_tests.hpp	Makes sender test helpers unconditional; changes random base/value to size_t.
libs/core/algorithms/tests/unit/algorithms/reduce_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/none_of_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/mismatch_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/mismatch_binary_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/is_sorted_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/is_heap_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/generaten_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/generate_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/foreach_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/foreach_scheduler.cpp	Adds Clang-version gating for problematic sender paths.
libs/core/algorithms/tests/unit/algorithms/findifnot_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/findif_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/findfirstof_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/findend_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/find_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/filln_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/fill_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/equal_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/equal_binary_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/destroy_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/countif_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/count_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/copyn_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/copy_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/any_of_tests.hpp	Makes sender test helpers unconditional; annotates unchecked optional access in test.
libs/core/algorithms/tests/unit/algorithms/any_of_sender.cpp	Adds Clang ICE workaround by compiling to a stub main on Clang<=20.
libs/core/algorithms/tests/unit/algorithms/all_of_tests.hpp	Makes sender test helpers unconditional; annotates unchecked optional access in test.
libs/core/algorithms/tests/unit/algorithms/all_of_sender.cpp	Adds Clang ICE workaround by compiling to a stub main on Clang<=20.
libs/core/algorithms/tests/unit/algorithms/adjacentfind_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/adjacentdifference_tests.hpp	Makes sender test helpers unconditional.
libs/core/algorithms/tests/unit/algorithms/CMakeLists.txt	Disables broad stdexec sender test set for Clang/AppleClang; additional Clang exclusions.
libs/core/algorithms/tests/performance/CMakeLists.txt	Disables foreach_report benchmark on Clang/AppleClang.
libs/core/algorithms/include/hpx/parallel/util/detail/algorithm_result.hpp	Always includes execution_base for sender traits.
libs/core/algorithms/include/hpx/parallel/algorithms/shift_right.hpp	Simplifies async result to return new_first directly.
examples/quickstart/sender_diamond.cpp	Adds local deprecation-warning suppression around deprecated CPO usage.
examples/quickstart/CMakeLists.txt	Disables sender_diamond example for Clang/AppleClang.
cmake/templates/std_headers.hpp.in	Makes stdexec-related diagnostic suppression unconditional (no longer guarded by HPX_HAVE_STDEXEC).
cmake/HPX_SetupStdexec.cmake	Adds stdexec header patching for modules builds; updates FetchContent include dirs to SYSTEM.
CMakeLists.txt	Makes stdexec mandatory and enables MSVC conforming preprocessor option for stdexec.
.github/workflows/tests.examples.targets	Adds 1d_stencil_8 example test target.
.github/workflows/macos_debug_fetch_hwloc.yml	Updates macOS CI exclusions for new/changed example targets.

Comments suppressed due to low confidence (1)

libs/core/execution/tests/unit/CMakeLists.txt:1

• This disables all execution unit tests when building with Clang/AppleClang, which is a very broad reduction in CI/test coverage. If only specific tests or warnings are problematic on Clang, prefer selectively excluding those tests (as done elsewhere with list(REMOVE_ITEM ...)) or applying targeted compile options/pragma suppression per-source/target instead of skipping the whole test suite.

# Copyright (c) 2014-2026 Hartmut Kaiser

[Copilot]

Pull request overview

Copilot reviewed 146 out of 167 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 147 out of 167 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

libs/core/execution_base/tests/unit/CMakeLists.txt:1

• This disables the entire execution_base unit test suite for Clang/AppleClang, which significantly reduces CI signal and increases the risk of undetected regressions on those compilers. If only a subset fails (e.g., due to deprecation warnings or specific ICEs), prefer disabling only the affected targets (via list(REMOVE_ITEM ...) or per-test conditions) or adding targeted compile options, rather than excluding the full suite.

# Copyright (c) 2019 Thomas Heller

[Copilot]

Pull request overview

Copilot reviewed 146 out of 167 changed files in this pull request and generated 4 comments.