gcc: Pointer Arith

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1 6.23 Arithmetic on 'void'- and Function-Pointers
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1 In GNU C, addition and subtraction operations are supported on pointers
1 to 'void' and on pointers to functions.  This is done by treating the
1 size of a 'void' or of a function as 1.
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1  A consequence of this is that 'sizeof' is also allowed on 'void' and on
1 function types, and returns 1.
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1  The option '-Wpointer-arith' requests a warning if these extensions are
1 used.
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