[cxx-abi-dev] Name mangling question

[nasgaard at ca.ibm.com]

Mark,  What happened to the N...E around the nested name.  The type should
be N6locale5_ImplE should it not?  S0_ is not the substitute for that.  Is
there a caveat here that drops them?

Howard W. Nasgaard
C++ Compiler Development
e-mail: nasgaard at ca.ibm.com
C2/KD2/8200/MKM
905-413-3683
Tie: 969-3683



                                                                                                                                                  
                      Mark Mitchell                                                                                                               
                      <mark at codesourcer        To:       Howard Nasgaard/Toronto/IBM at IBMCA, "cxx-abi-dev at codesourcery.com"                        
                      y.com>                    <cxx-abi-dev at codesourcery.com>                                                                    
                                               cc:                                                                                                
                      11/27/2002 10:43         Subject:  Re: [cxx-abi-dev] Name mangling question                                                 
                      AM                                                                                                                          
                                                                                                                                                  
                                                                                                                                                  





--On Wednesday, November 27, 2002 06:53:53 AM -0500 "nasgaard at ca.ibm.com"
<nasgaard at ca.ibm.com> wrote:

> I am having a problem understanding the mangling of function parameters
> for functions in a nested class.  Given the following test case:
>
> struct locale {
>    struct _Impl
>    {
>       void foo(_Impl&);
>    };
> };
>
> int main() {
>    locale::_Impl i;
>    i.foo(i);
> }
>
> g+ mangles this name as _ZN6locale5_Impl3fooERS0_
>
> It would seem that 6locale would have S_ as a substitution, and
> 6locale5_Impl would have S0_.  Given that the parameter is a nested name
> and so should be within N/E delimiters,  I don't see how g++ arives at
> that mangling.

One of the alternatives for the <type> production is <substitution>.

Therefore, you should never get to <nested-name> for the parameter.

Here is the mistake:

    <type> ::= R <type>
     <type> ::= <cv-qualifiers> <type>

That last line should be:

     <type> ::= <substitution>

There are definitely cases where two distinct strings will demangle to
the same name.  That's because the demangler doesn't try to check that
the input string uses substitutions.

--
Mark Mitchell                mark at codesourcery.com
CodeSourcery, LLC            http://www.codesourcery.com>