feat: GridSynth

[LonerDavid]

Check List

1. Does your submission pass tests by running make test?
2. If you have specified a [no ci] tag, does your submission also pass tests by running make test-docker?
3. Have you linted your code locally with make lint before submission?

Added

• New qcir gridsynth --epsilon command to decompose single-qubit RZ gates into Clifford+T sequences using the GridSynth algorithm
• Vendored cppgridsynth library under vendor/cppgridsynth/ with GMP/MPFR dependencies isolated to its own static library target
• GridSynthAdapter and GridSynthPass for integrating cppgridsynth into the qcir pipeline (src/qcir/gridsynth/)
• DOF test cases for gridsynth RZ decomposition and equivalence checking (tests/qcir/gridsynth/)

Changed

• HeaderFilterRegex in .clang-tidy restricted to src/ to prevent thousands of lint warnings from Homebrew GMP/MPFR system headers
• GMP/MPFR includes on the cppgridsynth target marked as SYSTEM PRIVATE to suppress external header warnings

Fixed

• Skip W gates produced by GridSynth to avoid incorrect circuit output

Removed

• N/A

[Copilot]

Pull request overview

Note

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

Vendors a new C++ port of the GridSynth algorithm (cppgridsynth) and wires it into qsyn as a new qcir gridsynth command that decomposes single-qubit RZ gates into Clifford+T sequences. The vendored library uses GMP/MPFR for arbitrary-precision arithmetic and is built as an isolated static library so those dependencies don't leak into the rest of qsyn.

Changes:

• Adds the full vendor/cppgridsynth/ tree (headers, sources, README/LICENSE) implementing the ring algebra, ODGP/TDGP/upright reduction, Diophantine solver, normal-form, and top-level pipeline.
• Adds src/qcir/gridsynth/ adapter + pass and a new qcir gridsynth CLI command, wired through src/cmd/qcir_cmd.cpp.
• Adds a CMake module cmake/cppgridsynth.cmake that builds the vendored library (linking GMP/MPFR only into it), plus end-to-end .dof/.log tests for the new command.

Reviewed changes

Copilot reviewed 11 out of 53 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
vendor/cppgridsynth/src/.cpp, include/cppgridsynth/.hpp	Vendored C++ port of pygridsynth: rings, region/grid ops, ODGP/TDGP, upright, Diophantine, normal form, top-level pipeline.
vendor/cppgridsynth/{README,LICENSE,UPSTREAM,.gitignore}	Vendored library docs and metadata.
vendor/README.md	Lists cppgridsynth as a vendored, optional-build dependency.
src/qcir/gridsynth/gridsynth_adapter.{hpp,cpp}	Thin bridge translating qsyn requests to cppgridsynth and converting back to a plain gate list (keeps GMP/MPFR headers out of qsyn core).
src/qcir/gridsynth/gridsynth_pass.{hpp,cpp}	Iterates a QCir, replaces each RZGate with the synthesized Clifford+T sequence.
src/cmd/qcir/gridsynth.cpp, src/cmd/qcir_cmd.cpp	Registers the new qcir gridsynth subcommand and its arguments.
cmake/cppgridsynth.cmake, CMakeLists.txt	New CMake module that builds cppgridsynth as a static lib, finds GMP/MPFR, and excludes the adapter from libqsyn.
tests/qcir/gridsynth/{dof,ref}/*	New end-to-end tests covering gridsynth and verifying equivalence vs. the original Rz at several angles.
.clang-tidy	Restricts HeaderFilterRegex so vendor/system headers (GMP/MPFR) aren't linted.
.gitignore	Whitelists tests/**/ref/*.log so the new reference logs are tracked.

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[Copilot]

Pull request overview

Copilot reviewed 11 out of 53 changed files in this pull request and generated 2 comments.

[Ferayer]

The following checks are failing:

• gcc test (Ubuntu) / build-and-test
• llvm-clang test (Ubuntu) / build-and-test
• Lint / Run linters

There seem to be two issues:

1. Ubuntu build-and-test fails because GMP/MPFR are missing

CMake stops here:

GridSynth requires GMP and MPFR, but they were not found.

Suggested fix: add the required packages to the Ubuntu GitHub Actions dependency install step:

sudo apt-get update
sudo apt-get install -y libgmp-dev libmpfr-dev

libgmp-dev and libmpfr-dev provide the GMP/MPFR headers and libraries required by GridSynth.

2. Lint fails because clang-format is needed

The linter shows formatting changes are required in:

src/qcir/gridsynth/gridsynth_pass.cpp

Suggested fix:

clang-format -i src/qcir/gridsynth/gridsynth_pass.cpp

Then commit and push the updated workflow/file so the CI can rerun.

suggestions are AI-generated.