Summary

• Keep the stable C ABI declarations in the unified public header include/infini/ops.h.
• Remove public InfiniOpsTensorDescriptor and descriptor create/destroy APIs.
• Make InfiniOpsTensor, InfiniOpsHandle, and InfiniOpsConfig opaque C handles.
• Configure tensor, handle, and config state through explicit create/destroy plus setter/getter APIs, avoiding public ABI layout commitments.
• Generate C operator declarations and wrappers for the whitelisted C ABI operator surface, currently infiniOpsAdd.
• Implement generated C wrappers as thin adapters over infini::ops::functional::<OpName>.
• Keep include/infini/c_ops.h generated only; the source-tree hand-written copy was removed.
• Rebase onto current origin/master after feat: add public C++ operator API #618 landed.

Motivation

This is the second PR in the public operator API split. After the public C++ functional API exists, the stable C ABI can be implemented on top of that layer instead of depending on private dispatch or backend kernel headers.

Target base branch: master.

Closes #N/A

Type of Change

• feat - new feature / new operator / new platform
• fix - bug fix
• N/A - perf - performance improvement (no behavioral change)
• refactor - code restructuring without behavior change
• test - adding or fixing tests only
• N/A - docs - documentation only
• build / ci - build system or CI configuration
• N/A - chore - tooling, formatting, or other non-code changes
• N/A - Breaking change (requires a ! in the Conventional Commits prefix or a BREAKING CHANGE: footer)

Platforms Affected

• CPU (WITH_CPU)
• NVIDIA (WITH_NVIDIA)
• Iluvatar (WITH_ILUVATAR)
• MetaX (WITH_METAX)
• Cambricon (WITH_CAMBRICON)
• Moore (WITH_MOORE)
• Ascend (WITH_ASCEND)
• PyTorch C++ bindings (WITH_TORCH)
• Build system / CMake / CI
• Python bindings / user-facing API

Test Results on Supported Platforms

Branch head: a8fa2760. Full platform runs used the requested accelerator visibility settings. The pytest command itself was invoked as plain pytest.

# NVIDIA
========= 9209 passed, 8665 skipped, 81 warnings in 364.51s (0:06:04) ==========
# MetaX
========= 8701 passed, 7655 skipped, 81 warnings in 418.01s (0:06:58) ==========
# Iluvatar
========= 7707 passed, 8649 skipped, 81 warnings in 641.09s (0:10:41) ==========
# Moore
========= 8474 passed, 7900 skipped, 99 warnings in 585.92s (0:09:45) ==========
# Cambricon
======== 5902 passed, 10070 skipped, 172 warnings in 999.13s (0:16:39) =========
# Ascend
========= 7400 passed, 8914 skipped, 71 warnings in 634.38s (0:10:34) ==========
PYTEST_INNER_RC=0

Additional remote style/check commands:

git diff --check
python3 -m py_compile scripts/generate_wrappers.py tests/test_c_api.py
ruff format --check scripts/generate_wrappers.py tests/test_c_api.py
ruff check scripts/generate_wrappers.py tests/test_c_api.py
/usr/bin/clang-format --dry-run -Werror include/infini/ops.h src/infini/ops.cc

Focused C ABI verification:

WITH_CPU=ON WITH_NVIDIA=ON WITH_TORCH=ON GENERATE_PYTHON_BINDINGS=ON CMake build/install passed.
tests/test_c_api.py: 3 passed in 1.42s

Benchmark / Performance Impact

N/A. This PR changes API wrapping, validation, and build/test integration. It does not change operator kernels or dispatch selection.

Notes for Reviewers

• This PR targets master; feat: add public C++ operator API #618 has landed and this branch was rebased on top of origin/master.
• The C ABI remains the stable ABI boundary. The C++ functional API remains a source/link convenience layer.
• InfiniOpsTensor is now an opaque handle, not a public value struct. It stores caller-owned buffer metadata internally and never owns or frees the caller's buffer.
• InfiniOpsHandle and InfiniOpsConfig are opaque handles with setter/getter APIs for stream, workspace, and implementation index.
• Operator-specific C declarations and wrappers are generated into generated/include/infini/c_ops.h and generated/src/c_ops.inc; src/infini/ops.cc keeps only the common C ABI adapter code.
• The earlier _musa_smoke_passes workaround is not present after the rebase. Moore coverage is restored by using the requested visibility environment.

Generated C ABI signature example:

INFINI_OPS_API InfiniOpsStatus infiniOpsAdd(
 InfiniOpsHandle handle, InfiniOpsConfig config,
 InfiniOpsTensor input, InfiniOpsTensor other, InfiniOpsTensor out);

Checklist

Title, Branch, and Commits

• PR title follows Conventional Commits: feat: build C API on functional operator API.
• Branch name follows the expected <type>/... form: feat/operator-c-api.
• Commit messages follow Conventional Commits.
• Branch is rebased onto current origin/master.
• No stray merge commits from master.
• No fixup! / squash! / wip commits remain.

Scope and Design

• Changes are scoped to the C ABI, tests, and required build/export integration.
• No dead code, commented-out blocks, debug prints, or ownerless TODOs were added.
• No unrelated formatting churn was added.
• Public API changes are intentional and reflected in tests.

General Code Hygiene

• Comments were added only where they explain non-obvious behavior.
• Modified and added files end with a single trailing newline.
• git diff --check passed.
• Comments and error messages are in English.
• Comments and error messages are complete sentences where applicable.

C++ Specific

• Code follows the repository's Google C++ style conventions to the extent verified by clang-format.
• clang-format --dry-run -Werror passed remotely.
• N/A - clang-tidy was not run in this session; this PR only adds the C ABI adapter layer and generated wrapper/build plumbing, not kernel code.
• Operator-facing parameter order is preserved: handle/config first for API control, then inputs, then outputs.
• No explicit exceptions are thrown through the C ABI; C++ allocation/runtime failures are caught and returned as InfiniOpsStatus.
• Error paths return InfiniOpsStatus and expose details through infiniOpsGetLastError.
• N/A - no kernel files or launchers were added.
• N/A - no new operator implementation classes were added.
• The C ABI uses opaque handle ownership internally and releases those handles through destroy APIs.

Python Specific

• Python changes are limited to smoke tests and generator code.
• ruff format --check and ruff check were run remotely and passed.
• Python smoke/full tests passed remotely on supported platforms.

Testing

• Full remote pytest results for all six requested platforms are recorded above.
• Iluvatar pytest passed after the host maintenance issue was resolved.
• New C ABI smoke coverage exists in tests/test_c_api.py.
• Existing external C++ smoke coverage remains in tests/test_cpp_api.py.
• N/A - no new operator numerical tests were added.
• Regression coverage was added for C API header/link behavior.

Build, CI, and Tooling

• Full build/install plus plain pytest was run remotely on NVIDIA, MetaX, Iluvatar, Cambricon, Moore, and Ascend.
• CMake configure/build/install paths were verified remotely.
• src/infini/ops.cc builds as CXX, not CUDA.
• No new runtime dependency was added.

Documentation

• N/A - README-level public C ABI documentation is deferred; this PR documents the ABI surface in include/infini/ops.h and smoke tests.
• Public API surface is represented in include/infini/ops.h and covered by smoke tests.
• Public ABI ownership semantics are represented by opaque handles and setter/getter APIs.

Security and Safety

• No secrets, access tokens, internal URLs, customer data, or personal hardware identifiers were committed.
• No third-party code was added.
• Tensor validation checks null pointers, shape, stride, byte size, dtype/device validity, and overflow-sensitive size calculations before calling the C++ API.