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Re: GCC 4.0 "C" question
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Re: GCC 4.0 "C" question


  • Subject: Re: GCC 4.0 "C" question
  • From: Steve Checkoway <email@hidden>
  • Date: Mon, 31 Oct 2005 13:57:03 -0800

On Oct 31, 2005, at 11:43 AM, Mark Dawson wrote:

I'm taking on some older code, and I'm getting this warning: "warning: target of assignment not really an lvalue; this will be a hard error in the future"

for the following line:

*((uint32_t*)dst)++ = *((uint32_t*)src)++;

The real problem is with ((uint32_t*)dst)++ (and with ((uint32_t*)src) ++). The reason is that (uint32_t*)dst is not a valid lvalue; however, *(uint32_t*)dst is.



Why is this code going to be an error in the future?

For now, I just replaced it with:
    uint32_t *aligned32Src, *aligned32Dst;
    aligned32Src            = (uint32_t *)src;
    aligned32Dst            = (uint32_t *)dst;
     *aligned32Dst++    = *aligned32Src++;


How about *(uint32_t*)dst = *(uint32_t*)src; dst = (typeof(dst))((uint32_t*)dst + 1); src = (typeof(src))((uint32_t*)src + 1);

Where you would probably want to use the actual type of dst and src in the case since typeof is a gcc extension.

- Steve

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 >GCC 4.0 "C" question (From: Mark Dawson <email@hidden>)

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