♻️🏁 Remove Windows-specific restrictions for dynamic QDMI device library handling

[burgholzer]

Description

Removes Windows-specific platform guards from dynamic QDMI device library loading infrastructure, adds cross-platform dynamic library loading macros, and updates tests to run uniformly across all platforms.

Fixes #1351

Checklist:

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
• I have updated the documentation to reflect these changes.
• I have added entries to the changelog for any noteworthy additions, changes, fixes, or removals.
• I have added migration instructions to the upgrade guide (if needed).
• The changes follow the project's style guidelines and introduce no new warnings.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

[coderabbitai]

📝 Walkthrough

Walkthrough

Removes Windows-only guards and makes dynamic QDMI device library support unconditional across platforms, introduces cross-platform dynamic-loading macros in the C++ driver, expands the Python binding add_dynamic_device_library with authentication/config parameters and explicit return type, and updates tests/CMake to run/load dynamic devices on all OSes.

Changes

Cohort / File(s)	Summary
Changelog CHANGELOG.md	Added entry noting removal of Windows-specific restrictions for dynamic QDMI device library handling and PR link for #1406.
C++ Header include/mqt-core/qdmi/Driver.hpp	Removed #ifndef _WIN32 guards so DynamicDeviceLibrary and Driver::addDynamicDeviceLibrary are available on all platforms; updated member docs.
C++ Implementation src/qdmi/Driver.cpp	Added cross-platform macros (DL_OPEN, DL_SYM, DL_CLOSE), replaced dlopen/dlsym/dlclose usage, updated preprocessor branches for Windows vs POSIX, and made addDynamicDeviceLibrary unconditional.
CMake (targets) src/qdmi/na/CMakeLists.txt, src/qdmi/sc/CMakeLists.txt, test/qdmi/CMakeLists.txt	Removed NOT WIN32 / WIN32 guards so dynamic NA/SC device targets and test compile definitions are created for all platforms.
Python Bindings bindings/fomac/fomac.cpp	Removed Windows compile guard; expanded add_dynamic_device_library signature to accept optional base_url, token, auth_file, auth_url, username, password, custom1–custom5; now returns fomac::Session::Device.
Python Stubs python/mqt/core/fomac.pyi	Removed docstring note that the function is Windows-unavailable; doc updated to reflect unconditional availability.
Python Tests test/python/fomac/test_fomac.py	Imported add_dynamic_device_library and removed platform-gated tests; consolidated to unconditional test invocation.
C++ Tests test/qdmi/test_driver.cpp	Removed Windows-only preprocessor guards; dynamic-device-related tests and DEVICES list now included unconditionally.

Sequence Diagram(s)

mermaid
sequenceDiagram
autonumber
participant Py as Python caller
participant Bind as bindings/fomac
participant Driver as qdmi::Driver
participant Loader as OS loader
participant Device as QDMI Device
Note over Bind,Driver: New params (auth/config) passed through
Py->>Bind: add_dynamic_device_library(path, prefix, auth...)
Bind->>Driver: addDynamicDeviceLibrary(path, prefix, config)
Driver->>Loader: DL_OPEN(library_path)
alt open success
Loader-->>Driver: handle
Driver->>Loader: DL_SYM(handle, factory_symbol)
Loader-->>Driver: symbol_ptr
Driver->>Device: instantiate via symbol_ptr
Driver-->>Bind: Device (wrapped)
Bind-->>Py: fomac::Session::Device
else open/error
Loader-->>Driver: error
Driver-->>Bind: throw/propagate error
Bind-->>Py: exception

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related issues

• Enable loading of dynamic QDMI device libraries on Windows #1351: Enables loading dynamic QDMI device libraries on Windows — directly aligned with removal of Windows guards and cross-platform loader additions.
• Refactor QDMI device architecture: Remove static device libraries #1352: Related to moving toward shared/dynamic device libraries and reducing static-only handling — changes here implement that across platforms.

Possibly related PRs

• ✨ QDMI authentication via FoMaC #1355: Touches the same binding and Driver changes (propagating DeviceSessionConfig/auth params); strongly related to signature/exposure changes.
• ✨ Instantiate Device from dynamic QDMI device library #1381: Alters add_dynamic_device_library to return a Device and exposes QDMI devices to bindings — overlaps with the return-type and binding updates.
• ✨ New QDMI Device to represent SC Devices #1328: Prior work on QDMI driver/device-loading behavior; shares overlapping changes to Driver.cpp and device registration.

Suggested labels

c++

Suggested reviewers

• ystade

Poem

🐰 I hopped through guards and patched the seam,
Now Windows and Unix share the same dream.
Libraries load where once they’d part —
One loader, one drive, one beating heart.
🥕✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 45.45% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: removing Windows-specific restrictions for dynamic QDMI device library handling, which is the primary focus of this PR.
Linked Issues check	✅ Passed	Changes meet the requirements of issue #1351 by removing Windows guards, adding cross-platform macros, and enabling dynamic library loading on Windows alongside Unix systems.
Out of Scope Changes check	✅ Passed	All changes are directly related to removing Windows-specific restrictions and implementing cross-platform dynamic library loading, with no unrelated modifications detected.
Description check	✅ Passed	The pull request description includes a summary of changes, references the fixed issue (#1351), includes a completed checklist with all items marked as done, and aligns well with the template structure.

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch windows-symbol-loading

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[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/qdmi/Driver.cpp	66.6%	1 Missing ⚠️

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