Re: [Tinycc-devel] type cast prob.

[Basile STARYNKEVITCH]

>>>>> "fabrice" == fabrice bellard <address@hidden> writes:

    fabrice> Quoting s duclos <address@hidden>:
    >> Hi,
    >> 
    >> Got this code after expanding up a macro by hand.
    >> 
    >> // t5.c main(){ float x; (int)x = (int)x; }


    fabrice> I am not sure that doing (int)x = [...] is correct.

It is documented as a GCC extension. See the 'lvalues::' subsection in
the C extension section of the GCC info manual.

I am citing it here:
________________________________________________________________
Generalized Lvalues
===================

   Compound expressions, conditional expressions and casts are allowed
as lvalues provided their operands are lvalues.  This means that you
can take their addresses or store values into them.
[...]

   A cast is a valid lvalue if its operand is an lvalue.  A simple
assignment whose left-hand side is a cast works by converting the
right-hand side first to the specified type, then to the type of the
inner left-hand side expression.  After this is stored, the value is
converted back to the specified type to become the value of the
assignment.  Thus, if `a' has type `char *', the following two
expressions are equivalent:

     (int)a = 5
     (int)(a = (char *)(int)5)
________________________________________________________________

I leave up to Fabrice to implement it in tcc. I've got no idea if it
is easy to do or not.

And by the way I don't know what Sylvain expect his code to do. Does
he want to round up a to its floor? Or should this be a No-Op (since
assigning the same bits to a float).

Regards.

-- 

Basile STARYNKEVITCH         http://starynkevitch.net/Basile/ 
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