The /analyze builder recently started giving this warning:

pdfium\xfa\fwl\basewidget\fwl_comboboximp.cpp(1101) : warning C6259: Labeled code is unreachable:  '(<expression> & 0x3000)' in a switch-expr cannot evaluate to '0x400'.
pdfium\xfa\fwl\basewidget\fwl_comboboximp.cpp(1104) : warning C6259: Labeled code is unreachable:  '(<expression> & 0x3000)' in a switch-expr cannot evaluate to '0x800'.

The code in question is:

  switch (dwStylExes & FWL_STYLEEXT_CMB_ListItemAlignMask) {
    case FWL_STYLEEXT_CMB_ListItemCenterAlign: {
      dwAdd |= FWL_STYLEEXT_LTB_CenterAlign;
    }
    case FWL_STYLEEXT_CMB_ListItemRightAlign: {
      dwAdd |= FWL_STYLEEXT_LTB_RightAlign;
    }
    default: { dwAdd |= FWL_STYLEEXT_LTB_LeftAlign; }
  }

and indeed the constants do not overlap.

#define FWL_STYLEEXT_CMB_ListItemCenterAlign (1L << 10)
#define FWL_STYLEEXT_CMB_ListItemRightAlign (2L << 10)
...
#define FWL_STYLEEXT_CMB_ListItemAlignMask (3L << 12)

The code appears to have been broken since its inception - it's not clear why it is now triggering warnings. Perhaps something about the XFA changes?

Anyway, it's broken. It needs to be fixed with care since the fix will change its behavior.

Can you investigate or reassign?

Tracking bug for /analyze is 427616.