Re: [PATCH] jit: Make recording::memento non-copyable

[David Malcolm <dmalcolm@redhat.com>]

On Thu, 2022-07-14 at 19:44 +0100, Jonathan Wakely wrote:
> These polymoprhic types don't appear to be copied anywhere. Rather
> than
> trying to reason about what it means to copy a polymoprhic base
> without
> copying the derived part, disable copies. This also avoids a
> potential
> double-free if a recorindg::string object does somehow get copied (it
> owns a pointer to dynamically allocated memory, but the implicit copy
> constructor will just make shallow copies).
> 
> Tested x86_64-linux with --enable-languages=c,c++,jit --enable-host-
> shared
> 
> OK for trunk?

[CCing jit mailing list]

Thanks; OK for trunk.

> 
> -- >8 --
> 
> gcc/jit/ChangeLog:
> 
>         * jit-recording.h (recording::memento): Define copy
> constructor
>         and copy assignment operator as deleted.
>         (recording::string): Likewise.
>         (recording::string::c_str): Add const qualifier.
> ---
>  gcc/jit/jit-recording.h | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/gcc/jit/jit-recording.h b/gcc/jit/jit-recording.h
> index 0dfb42f2676..8610ea988bd 100644
> --- a/gcc/jit/jit-recording.h
> +++ b/gcc/jit/jit-recording.h
> @@ -405,6 +405,9 @@ public:
>    virtual void write_reproducer (reproducer &r) = 0;
>    virtual location *dyn_cast_location () { return NULL; }
>  
> +  memento (const memento&) = delete;
> +  memento& operator= (const memento&) = delete;
> +
>  protected:
>    memento (context *ctxt)
>    : m_ctxt (ctxt),
> @@ -436,13 +439,16 @@ public:
>    string (context *ctxt, const char *text, bool escaped);
>    ~string ();
>  
> -  const char *c_str () { return m_buffer; }
> +  const char *c_str () const { return m_buffer; }
>  
>    static string * from_printf (context *ctxt, const char *fmt, ...)
>      GNU_PRINTF(2, 3);
>  
>    void replay_into (replayer *) final override {}
>  
> +  string (const string&) = delete;
> +  string& operator= (const string&) = delete;
> +
>  private:
>    string * make_debug_string () final override;
>    void write_reproducer (reproducer &r) final override;