goto label inside of if statement topic

On 1/23/2014 2:32 PM, W Karas wrote:
> I was surprised to find that this code:
>
> struct A { A(); ~A(); };
>
> void bar();
>
> void foo(bool f)
> {
> if (0)
> {
> LAB: ;
> }
> else
> {
> A a;
>
> if (f) goto LAB;
>
> bar();
> }
> }
>
> will compile without warnings using GCC 4.7.3, even with -Wall and -Wextra .
>
> The point, in case you were wondering, would be a macro-based "named block" pseudo-construct, where the block could be exited from any depth of block nesting, for example:
>
> #define BLOCK(NAME) if (0) { NAME: ; } else
> #define EXITBLOCK(NAME) goto NAME;
>
> struct A { A(); ~A(); };
>
> void bar();
>
> void foo(bool f)
> {
> BLOCK(XYZ)
> {
> A a;
>
> if (f) EXITBLOCK(XYZ)
>
> bar();
> }
> }
>

And it actually skips the 'else' part when jumping into the 'if'
section, yes? And how well do optimizers handle it?

V
--
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