Tried to fix the error that can't find libomp path when building windows wheel.

Author: Fantasy201

.github/workflows/python-app.yml

@@ -370,6 +370,39 @@ jobs:
           where.exe cl
           where.exe link
 
+      - name: Locate MSVC LLVM OpenMP runtime (Windows)
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          $vswhere = "${env:ProgramFiles(x86)}\Microsoft Visual Studio\Installer\vswhere.exe"
+          $installPath = & $vswhere -latest -products * -property installationPath
+          if (-not $installPath) {
+            throw "vswhere did not return a Visual Studio installation path"
+          }
+
+          $patterns = @(
+            "$installPath\VC\Redist\MSVC\*\x64\Microsoft.VC*.OpenMP.LLVM\libomp140.x86_64.dll",
+            "$installPath\VC\Redist\MSVC\*\debug_nonredist\x64\Microsoft.VC*.OpenMP.LLVM\libomp140.x86_64.dll",
+            "$installPath\VC\Tools\Llvm\x64\bin\libomp140.x86_64.dll",
+            "$installPath\VC\Tools\Llvm\x64\bin\libomp140.dll"
+          )
+
+          $dll = $null
+          foreach ($pattern in $patterns) {
+            $match = Get-ChildItem -Path $pattern -ErrorAction SilentlyContinue | Select-Object -First 1
+            if ($match) {
+              $dll = $match
+              break
+            }
+          }
+
+          if (-not $dll) {
+            throw "libomp140*.dll not found under Visual Studio install: $installPath"
+          }
+
+          Write-Host "Found OpenMP runtime: $($dll.FullName)"
+          "LIBOMP_DLL_DIR=$($dll.DirectoryName)" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
+
       # Install dependencies with fallback strategy
       - name: Install dependencies
         run: |
@@ -421,7 +454,7 @@ jobs:
 
           # 显式将 runner 级别的环境变量传入 cibuildwheel 的隔离 venv
           # 避免 $LIBOMP_PATH 因隐式继承失败而导致 delocate 找不到 libomp
-          CIBW_PASS_ENV: "LIBOMP_PATH SEQUENZO_LIBOMP_PREFIX SEQUENZO_ENABLE_OPENMP MACOSX_DEPLOYMENT_TARGET GITHUB_WORKSPACE"
+          CIBW_PASS_ENV: "LIBOMP_PATH LIBOMP_DLL_DIR SEQUENZO_LIBOMP_PREFIX SEQUENZO_ENABLE_OPENMP MACOSX_DEPLOYMENT_TARGET GITHUB_WORKSPACE"
 
           # macOS: Set OpenMP environment with proper library paths and rpath for bundling
           # REPAIR_LIBRARY_PATH 是 libomp 路径的副本，专用于在 repair 阶段
@@ -551,6 +584,9 @@ jobs:
 
           # Windows: setup MSVC environment
           CIBW_BEFORE_BUILD_WINDOWS: |
+            echo "Installing wheel repair dependencies"
+            python -m pip install --upgrade pip
+            python -m pip install delvewheel
             echo "Setting up MSVC environment"
             call "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
             for /f "usebackq tokens=*" %%i in (`"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -find VC\Tools\MSVC\**\bin\Hostx64\x64`) do set "VCTOOLS_BIN=%%i"
@@ -562,8 +598,6 @@ jobs:
             where cl
             where link
             echo "Using minimal build dependencies"
-            python -m pip install --upgrade pip
-            python -m pip install delvewheel
 
           CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: python maintenance_scripts/repair_windows_wheel.py "{dest_dir}" "{wheel}"
 

maintenance_scripts/repair_windows_wheel.py

@@ -15,6 +15,7 @@
 """
 from __future__ import annotations
 
+import importlib.util
 import os
 import shutil
 import subprocess
@@ -31,6 +32,21 @@
 # delvewheel invocation
 # ---------------------------------------------------------------------------
 
+def _ensure_delvewheel() -> None:
+    """Install delvewheel into the active cibuildwheel venv when missing."""
+    if importlib.util.find_spec("delvewheel") is not None:
+        return
+
+    print("[repair] delvewheel not found in build venv; installing...")
+    result = subprocess.run(
+        [sys.executable, "-m", "pip", "install", "delvewheel"],
+        check=False,
+    )
+    if result.returncode != 0 or importlib.util.find_spec("delvewheel") is None:
+        print("[repair] ERROR: failed to install delvewheel", file=sys.stderr)
+        raise SystemExit(1)
+
+
 def _delvewheel_cmd(*args: str) -> list[str]:
     """Invoke delvewheel via the active Python (Scripts/ may be off PATH)."""
     return [sys.executable, "-m", "delvewheel", *args]
@@ -122,6 +138,61 @@ def _find_omp_dll_via_vswhere(vswhere: Path) -> Path | None:
                 print(f"[repair] Found DLL under VS install root: {matches[0]}")
                 return matches[0]
 
+        redist_match = _find_omp_dll_via_redist(install_root)
+        if redist_match:
+            return redist_match
+
+    return None
+
+
+def _find_omp_dll_via_redist(install_root: Path | None = None) -> Path | None:
+    """Search VC Redist trees where MSVC ships libomp140 for /openmp:llvm."""
+    roots: list[Path] = []
+    if install_root is not None and install_root.is_dir():
+        roots.append(install_root)
+    roots.extend(
+        [
+            Path("C:/Program Files/Microsoft Visual Studio/2022/Enterprise"),
+            Path("C:/Program Files/Microsoft Visual Studio/2022/Community"),
+            Path("C:/Program Files/Microsoft Visual Studio/2022/Professional"),
+        ]
+    )
+
+    seen: set[Path] = set()
+    for root in roots:
+        try:
+            resolved = root.resolve()
+        except OSError:
+            continue
+        if resolved in seen or not resolved.is_dir():
+            continue
+        seen.add(resolved)
+
+        for name in _MSVC_OMP_DLL_NAMES:
+            for pattern in (
+                f"VC/Redist/MSVC/*/x64/Microsoft.VC*.OpenMP.LLVM/{name}",
+                f"VC/Redist/MSVC/*/debug_nonredist/x64/Microsoft.VC*.OpenMP.LLVM/{name}",
+            ):
+                matches = sorted(resolved.glob(pattern))
+                if matches:
+                    print(f"[repair] Found DLL via VS redist: {matches[0]}")
+                    return matches[0]
+
+    return None
+
+
+def _find_omp_dll_from_env() -> Path | None:
+    """Use LIBOMP_DLL_DIR when CI has already resolved the OpenMP runtime."""
+    env_dir = os.environ.get("LIBOMP_DLL_DIR", "").strip()
+    if not env_dir:
+        return None
+
+    directory = Path(env_dir)
+    for name in _MSVC_OMP_DLL_NAMES:
+        candidate = directory / name
+        if candidate.is_file():
+            print(f"[repair] Found DLL via LIBOMP_DLL_DIR: {candidate}")
+            return candidate
     return None
 
 
@@ -143,6 +214,10 @@ def _find_omp_dll_fallback() -> Path | None:
 
 
 def find_omp_dll() -> Path | None:
+    dll = _find_omp_dll_from_env()
+    if dll:
+        return dll
+
     vswhere = _find_vswhere()
     if vswhere:
         print(f"[repair] Using vswhere: {vswhere}")
@@ -152,6 +227,11 @@ def find_omp_dll() -> Path | None:
         print("[repair] vswhere did not find libomp140*.dll; trying fallback paths...")
     else:
         print("[repair] vswhere.exe not found; trying fallback paths...")
+
+    dll = _find_omp_dll_via_redist()
+    if dll:
+        return dll
+
     return _find_omp_dll_fallback()
 
 
@@ -178,6 +258,8 @@ def main() -> int:
         print("Usage: repair_windows_wheel.py <dest_dir> <wheel>", file=sys.stderr)
         return 2
 
+    _ensure_delvewheel()
+
     dest = Path(sys.argv[1]).resolve()
     wheel = Path(sys.argv[2]).resolve()
     dest.mkdir(parents=True, exist_ok=True)

tests/openmp/test_repair_windows_wheel.py

@@ -0,0 +1,43 @@
+import importlib.util
+import sys
+from pathlib import Path
+
+
+def _load_repair_module():
+    repo_root = Path(__file__).resolve().parents[2]
+    module_path = repo_root / "maintenance_scripts" / "repair_windows_wheel.py"
+    spec = importlib.util.spec_from_file_location("repair_windows_wheel", module_path)
+    module = importlib.util.module_from_spec(spec)
+    assert spec.loader is not None
+    sys.modules[spec.name] = module
+    spec.loader.exec_module(module)
+    return module
+
+
+def test_find_omp_dll_prefers_libomp_dll_dir(monkeypatch, tmp_path):
+    repair = _load_repair_module()
+    dll_dir = tmp_path / "openmp"
+    dll_dir.mkdir()
+    dll = dll_dir / "libomp140.x86_64.dll"
+    dll.write_bytes(b"fake")
+
+    monkeypatch.setenv("LIBOMP_DLL_DIR", str(dll_dir))
+    assert repair.find_omp_dll() == dll
+
+
+def test_find_omp_dll_via_redist_glob(tmp_path):
+    repair = _load_repair_module()
+    redist_dir = (
+        tmp_path
+        / "VC"
+        / "Redist"
+        / "MSVC"
+        / "14.44.35207"
+        / "x64"
+        / "Microsoft.VC143.OpenMP.LLVM"
+    )
+    redist_dir.mkdir(parents=True)
+    dll = redist_dir / "libomp140.x86_64.dll"
+    dll.write_bytes(b"fake")
+
+    assert repair._find_omp_dll_via_redist(tmp_path) == dll

tests/openmp/test_windows_wheel_workflow.py

@@ -14,10 +14,14 @@ def test_windows_cibuildwheel_smoke_test_uses_cmd_safe_python():
 
 def test_windows_wheel_repair_verifies_bundled_openmp_dlls():
     workflow = WORKFLOW.read_text(encoding="utf-8")
-
-    assert "delvewheel show" in workflow
-    assert "sequenzo.libs" in workflow
-    assert "libomp140" in workflow
+    repair_script = (
+        WORKFLOW.parents[2] / "maintenance_scripts" / "repair_windows_wheel.py"
+    ).read_text(encoding="utf-8")
+
+    assert "delvewheel show" in repair_script
+    assert "LIBOMP_DLL_DIR" in workflow
+    assert "sequenzo.libs" in repair_script
+    assert "libomp140" in repair_script
 
 
 def test_windows_conda_smoke_installs_repaired_wheel():

tests/test_build_release_boundaries.py

@@ -30,9 +30,13 @@ def test_macos_wheel_repair_fails_instead_of_copying_unrepaired_wheel():
     assert "build_macos_ci_libomp.sh" in source
     assert "repair_windows_wheel.py" in source
     assert 'CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: python maintenance_scripts/repair_windows_wheel.py' in source
+    assert "LIBOMP_DLL_DIR" in source
+    assert "Locate MSVC LLVM OpenMP runtime (Windows)" in source
     repair_script = (repo_root / "maintenance_scripts" / "repair_windows_wheel.py").read_text()
     assert "delvewheel did not emit a wheel; copying built wheel as-is" in repair_script
     assert '"-m", "delvewheel"' in repair_script or "'-m', 'delvewheel'" in repair_script
+    assert "_ensure_delvewheel" in repair_script
+    assert "LIBOMP_DLL_DIR" in repair_script
     assert "libomp.dll" not in repair_script or "libomp140" in repair_script
     assert "bundled OpenMP DLLs" in repair_script
     assert (repo_root / "maintenance_scripts" / "repair_windows_wheel.py").is_file()