Re: typedefs and structs

[Vadim Lobanov <vlobanov@speakeasy.net>]

On Thu, 10 Nov 2005, Kyle Moffett wrote:

> On Nov 10, 2005, at 08:27:18, Nikita Danilov wrote:
> > extern declaration in your version of bar() cannot refer to the
> > automatic variable myvar in foo().
>
> int foo;

Except foo is not an automatic variable within show(). When the variable
is global, then there's no argument. It was a question of when foo is
local and bar() would get a const pointer to the local.

> void bar(const int *local_var) {
>      foo = *local_var + 1;
> }
>
> void show(void) {
>      printf("%d\n", foo);
>      bar(&foo);
>      printf("%d\n", foo);
> }
>
> If GCC thought it could arbitrarily cache anything it wanted to, then
> code like this would die.  There is a whole mess of code in GCC
> designed specifically to watch for and avoid aliasing issues like these.
>
> Cheers,
> Kyle Moffett
>
> --
> Debugging is twice as hard as writing the code in the first place.
> Therefore, if you write the code as cleverly as possible, you are, by
> definition, not smart enough to debug it.
>    -- Brian Kernighan
>
>

-Vadim Lobanov
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