Re: [C++ PATCH] Fix up array initializations from compound literal (PR c++/40948)

[Jakub Jelinek <jakub at redhat dot com>]

On Mon, Aug 03, 2009 at 05:18:53PM -0400, Jason Merrill wrote:
> On 08/03/2009 01:17 PM, Jakub Jelinek wrote:
>> 	* init.c (build_vec_init): Add CLEANUP_POINT_EXPR around
>> 	TRY_STMTS (try_block).
>
> I don't think this is right; I would expect it to mean that we destroy  
> the compound literal right after we initialize it.  I'll poke at this  
> some more.

I think it is destroyed after it is copied.
struct M
{
  M ();
  ~M ();
  M (const M &);
};

void
foo ()
{
  M m[2] = (M[2]) { M (), M () };
}

with the patch gives following.  AFAICS D.2115 (the compund literal) is only
ever used inside of the TRY_BLOCK's TRY_STMTs, never later on.

  D.2117 = &m[0];
  D.2118 = D.2117;
  D.2119 = 1;
  try
    {
      M::M (&D.2115[0]);
      M::M (&D.2115[1]);
      try
        {
          D.2120 = &D.2115[0];
          goto <D.2133>;
          <D.2131>:
          M::M (D.2118, D.2120);
          D.2118 = D.2118 + 1;  
          D.2120 = D.2120 + 1;  
          D.2119 = D.2119 - 1;  
          <D.2133>:
          D.2132 = D.2119 != -1;
          if (D.2132 != 0) goto <D.2131>; else goto <D.2129>;
          <D.2129>:
        }
      finally
        {
	  // This is the compound literal cleanup
          {
            struct M * D.2116;

            D.2116 = &D.2115[2];
            <D.2126>:
            if (D.2116 == &D.2115[0]) goto <D.2127>; else goto <D.2128>;
            <D.2128>:
            D.2116 = D.2116 + -1;
            M::~M (D.2116);
            goto <D.2126>; 
            <D.2127>:
          }
        }  
    }
  catch
    {  
      // And this is the build_vec_init TRY_BLOCK cleanup.
      {
        struct M * D.2122;

        if (D.2117 != 0B) goto <D.2134>; else goto <D.2135>;
        <D.2134>:
        D.2136 = 1 - D.2119;
        D.2137 = (long unsigned int) D.2136;
        D.2122 = D.2117 + D.2137;
        <D.2138>:
        if (D.2122 == D.2117) goto <D.2139>; else goto <D.2140>;
        <D.2140>:
        D.2122 = D.2122 + -1;
        M::~M (D.2122);
        goto <D.2138>; 
        <D.2139>:
        goto <D.2141>;
        <D.2135>:
        <D.2141>:
      }
    }  

	Jakub