c++/7239: g++ rejects pointer to own class type in throw statement

[mayer at tux dot org]

>Number:         7239
>Category:       c++
>Synopsis:       g++ rejects pointer to own class type in throw statement
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 08 18:36:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     
>Release:        3.0.2
>Organization:
tux.org
>Environment:
System: SunOS hydra 5.6 Generic_105181-16 sun4u sparc SUNW,Ultra-2
Architecture: sun4
host: sparc-sun-solaris2.6
build: sparc-sun-solaris2.6
target: sparc-sun-solaris2.6
configured with: ../gcc/configure --prefix=/work/hyd01/td/sw/gcc_3_0_2_release --disable-nls --disable-threads --disable-shared --enable-languages=c,c++,f77,objc
>Description:
G++ does not compile any class that has a pointer to its own class type as an
exception type in the throw specification of a member function.
>How-To-Repeat:
Assume the file bug.cc contains the following three lines:
struct X {
  void f() throw (X*) { throw this;}
};

Then the command "g++ -c bug.cc" creates the error message
bug.cc:2: invalid use of undefined type `struct X'
bug.cc:1: forward declaration of `struct X'

"g++ -c -E bug.cc" reports:
# 1 "bug.cc"
struct X {
  void f() throw (X*) { throw this;}
};

>Fix:
Do not have one. Work-around: Use a wrapper class, as in:

struct X;
struct Y {
  Y(const X * x) : xp(x) {}
  const X * xp;
};
struct X {
  void f() throw (Y) { throw Y(this);}
};

This compiles fine.

>Release-Note:
>Audit-Trail:
>Unformatted: