In this particular case t shadows transpose of the base class Matx:
types.hpp:1805:14: warning: declaration of ‘t’ shadows a member of
'this' [-Wshadow]
Changelog gcc 4.8: The option -Wshadow no longer warns if a declaration
shadows a function declaration.
This warning is problematic because it prevents the module
opencv_contrib/modules/ruby to pass the build process
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