Merge pull request #6176 from hjmjohnson/eigen-5.0.1-update

ENH: Update vendored Eigen3 to 5.0.1+master; verify USE_SYSTEM 3.3/3.4/5.x

Author: hjmjohnson

Modules/Core/Common/include/itkMacro.h

@@ -117,6 +117,14 @@ namespace itk
 #  define ITK_GCC_SUPPRESS_Warray_bounds
 #endif
 
+// -Wmaybe-uninitialized is a real-GCC-only warning name; Apple Clang emits
+// -Wunknown-warning-option for it (which ITK's dashboard treats as fatal).
+#if defined(__GNUC__) && !defined(__clang__)
+#  define ITK_GCC_SUPPRESS_Wmaybe_uninitialized ITK_PRAGMA(GCC diagnostic ignored "-Wmaybe-uninitialized")
+#else
+#  define ITK_GCC_SUPPRESS_Wmaybe_uninitialized
+#endif
+
 // For Clang only (and not GCC):
 #if defined(__clang__) && defined(__has_warning)
 #  define ITK_CLANG_PRAGMA_PUSH ITK_PRAGMA(clang diagnostic push)

Modules/Core/Common/include/itkSymmetricEigenAnalysis.h

@@ -1029,8 +1029,16 @@ class ITK_TEMPLATE_EXPORT SymmetricEigenAnalysisFixedDimension
       }
     }
     using EigenSolverType = Eigen::SelfAdjointEigenSolver<EigenLibMatrixType>;
+    // GCC's IPA cannot prove that Eigen 5's analytical 3x3 SelfAdjointEigenSolver
+    // fully writes m_eivalues; Eigen's own CMakeLists adds -Wno-maybe-uninitialized
+    // for the same reason (see Modules/ThirdParty/Eigen3/.../CMakeLists.txt).
+    // clang-format off
+    ITK_GCC_PRAGMA_PUSH
+    ITK_GCC_SUPPRESS_Wmaybe_uninitialized
     const EigenSolverType solver(inputMatrix, Eigen::EigenvaluesOnly);
     auto                  eigenValues = solver.eigenvalues();
+    ITK_GCC_PRAGMA_POP
+    // clang-format on
     if (m_OrderEigenValues == EigenValueOrderEnum::OrderByMagnitude)
     {
       detail::sortEigenValuesByMagnitude(eigenValues, VDimension);

Modules/ThirdParty/Eigen3/UpdateFromUpstream.sh

@@ -6,10 +6,16 @@ shopt -s dotglob
 
 readonly name="Eigen3"
 readonly ownership="Eigen Upstream <kwrobot@kitware.com>"
+# ITK has applied a small number of post-import patches under itkeigen/
+# (e.g., SelfadjointMatrixVector.h pzero init), so the tree no longer
+# bytewise matches the previous import commit's tree. Use log-based
+# matching instead of exact-tree matching for the previous-import probe.
+exact_tree_match=false
 readonly subtree="Modules/ThirdParty/Eigen3/src/itkeigen"
 readonly repo="https://github.com/InsightSoftwareConsortium/eigen"
-readonly tag="for/itk-20260305-4c99fca"
+readonly tag="for/itk-20260501-879885e1"
 readonly paths="
+Eigen/AccelerateSupport
 Eigen/Cholesky
 Eigen/CholmodSupport
 Eigen/Core
@@ -20,6 +26,7 @@ Eigen/Geometry
 Eigen/Householder
 Eigen/IterativeLinearSolvers
 Eigen/Jacobi
+Eigen/KLUSupport
 Eigen/LU
 Eigen/MetisSupport
 Eigen/OrderingMethods
@@ -38,7 +45,9 @@ Eigen/StdDeque
 Eigen/StdList
 Eigen/StdVector
 Eigen/SuperLUSupport
+Eigen/ThreadPool
 Eigen/UmfPackSupport
+Eigen/Version
 Eigen/src
 
 COPYING.BSD

Modules/ThirdParty/Eigen3/src/itkeigen/.gitattributes

@@ -1,3 +1,9 @@
+*.sh                         eol=lf
+debug/msvc/*.dat             eol=crlf
+debug/msvc/*.natvis          eol=crlf
+
+# ITK fork: relax content-checks for the largest Eigen header so
+# UpdateFromUpstream.sh / KWStyle hooks do not reject the import.
 * -whitespace
 Eigen/src/misc/lapacke.h hooks-max-size=1500000
 Eigen/src/misc/lapacke.h hooks.MaxObjectKiB=2048