Re: Clean up pretty printers [10/n]

[Jakub Jelinek <jakub at redhat dot com>]

On Thu, Aug 22, 2013 at 05:27:54AM -0500, Gabriel Dos Reis wrote:
> 	* error.c (init_error): Remove calls to pp_construct and
> 	pp_cxx_pretty_printer_init.  Initialize cxx_pp with placement-new.
> 	* cxx-pretty-print.h (cxx_pretty_printer::cxx_pretty_printer): Declare.
> 	(cxx_pretty_printer_init): Remove.
> 	* cxx-pretty-print.c (cxx_pretty_printer::cxx_pretty_printer):
> 	Rename from cxx_pretty_printer_init.  Adjust.
> 	* cp-objcp-common.c (cxx_initialize_diagnostics): Simplify
> 	initialization of C++ diagnostics pretty printer.

> --- cp/error.c	(revision 201904)
> +++ cp/error.c	(working copy)
> @@ -33,6 +33,8 @@
>  #include "pointer-set.h"
>  #include "c-family/c-objc.h"
>  
> +#include <new>                    // For placement-new.
> +
>  #define pp_separate_with_comma(PP) pp_cxx_separate_with (PP, ',')
>  #define pp_separate_with_semicolon(PP) pp_cxx_separate_with (PP, ';')
>  
> @@ -109,8 +111,7 @@
>    diagnostic_finalizer (global_dc) = cp_diagnostic_finalizer;
>    diagnostic_format_decoder (global_dc) = cp_printer;
>  
> -  pp_construct (cxx_pp, NULL, 0);
> -  pp_cxx_pretty_printer_init (cxx_pp);
> +  new (cxx_pp) cxx_pretty_printer ();

Unfortunately this always leaks memory,
static cxx_pretty_printer scratch_pretty_printer;
is constructed first during static initialization, where it e.g. allocates
through XNEW the buffer, and then when init_error is called, it ignores
the old content of scratch_pretty_printer and constructs the same objects
again.  Why is the new (cxx_pp) cxx_pretty_printer (); line needed at all?
Isn't it already constructed with the right ctor?
Or, shouldn't it at least first try to call destructor?

I think there are more spots with placement new, perhaps all have the same
issue?

	Jakub