Do I have a gcc optimization bug or a C code problem?

Question

Test the following code:

#include 
#include 
main()
{
    const char *yytext=\"0\";
    const float f=(float)atof(yytext);
    siz         


        

Answer 1

In the C99 standard, this is covered by the following rule in 6.5-7:

An object shall have its stored value accessed only by an lvalue expression that has one of the following types:73)

• a type compatible with the effective type of the object,

• a qualified version of a type compatible with the effective type of the object,

• a type that is the signed or unsigned type corresponding to the effective type of the object,

• a type that is the signed or unsigned type corresponding to a qualified version of the effective type of the object,

• an aggregate or union type that includes one of the aforementioned types among its members (including, recursively, a member of a subaggregate or contained union), or

• a character type.

The last item is why casting first to a (char*) works.