Warning C4127 compiling Eigen v3.4.0 with VS2019 v16.10.4

Summary

The following warning appears in many Eigen files: warning C4127: conditional expression is constant

Some cases:

• CoreEvaluators.h (204, ...)
• CwiseNullaryOp.h (148)
• GeneralBlockPanelKernel.h (1429, ...)
• Memory.h (405, ...)
• SparseCompressedBase.h (58)
• SimplicialCholesky.h (664)

and many others...

Environment

• Operating System : Windows
• Architecture : x86
• Eigen Version : 3.4.0
• Compiler Version : VS2019 v16.10.4
• Compile Flags : -O2
• Vector Extension : SSE2