[Bug c++/33012] New: ICE on throwing copy of object returned by reference from method with traits-deduced return-type

[Bug c++/33012] New: ICE on throwing copy of object returned by reference from method with traits-deduced return-type

[raymond at corvil dot com]

Compiling a .cpp file with the following contents triggers an internal compiler
error:
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

/*
 * The two Traits templates here are essentially std::iterator_traits 
 * stripped right down with just enough left to make the test-case work:
 */

template<typename _Type> struct Traits;
template<typename _Type>
struct Traits<_Type *> { typedef _Type& reference; };


/*
 * TraitedWrapper is essentially __gnu_cxx::__normal_iterator stripped
 * to the minimum required to make the test-case work:
 */

template<typename _Pointer>
class TraitedWrapper {
public:
        typedef typename Traits<_Pointer>::reference    reference;


        TraitedWrapper(const _Pointer pointer) : pointer_(pointer) { }

        reference get() const   { return *pointer_; }

private:
        _Pointer pointer_;
};


/*
 * SpecialWrapper is essentially a form of TraitedWrapper that is
 * specialised for the pointer case in the way that Traits is.
 */

template<typename _Type>        class SpecialWrapper;
template<typename _Type>
class SpecialWrapper<_Type *> {
public:
        SpecialWrapper(_Type *pointer) : pointer_(pointer) { }

        _Type get() const       { return *pointer_; }

private:
        _Type *pointer_;
};




/*
 * inner() throws a copy of an object returned by reference from
 * a method whose return-type is sometimes deduced by some template
 * indirection.  It's templated to show what happens with different
 * combinations of return-type deduction and copy-constructor origin.
 */

template<template<typename> class _Wrapper, typename _Type>
void    inner()
{
        _Type orig;
        _Wrapper<_Type *> wrapper(&orig);

/*
 * No problem copy-constructing a stack-variable from the iterator:
 */
        _Type copy(wrapper.get());
        if( true )
/*
 * No problem throwing the stack-variable:
 */
                throw copy;
        else
/*
 * ICE can happen here, when directly throwing a copy,
 * depending on template parameters:
 */
                throw _Type(wrapper.get());
}


struct Generated { };

struct Manual {
        Manual() { }
        Manual(const Manual&) { }
};


void    outer()
{
        inner<SpecialWrapper, Manual>();
        inner<SpecialWrapper, Generated>();
        inner<TraitedWrapper, Manual>();

/*
 * ICE when the wrapper get-method has a traits-deduced return-type
 * and the class has a compiler-supplied copy-constructor:
 */
        inner<TraitedWrapper, Generated>();
}

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


Issued command-line:
    g++ -Wall -W -Wundef -Wpointer-arith -g -O0 -c -o /dev/null bug.cpp

Resulting output:
    bug.cpp: In function 'void inner() [with _Wrapper = TraitedWrapper, _Type =
Generated]':
    bug.cpp:101:   instantiated from here
    bug.cpp:79: internal compiler error: in stabilize_call, at cp/tree.c:2248
    Please submit a full bug report,
    ...

Full output from running with "-v --save-temps" is as follows:
    g++ -v -save-temps -Wall -W -Wundef -Wpointer-arith -g -O0 -c -o /dev/null
bug.cpp
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc-4.1.1/configure --enable-shared --enable-threads=posix
--enable-__cxa_atexit --enable-clocale=gnu --enable-languages=c,c++
Thread model: posix
gcc version 4.1.1
 /usr/local/libexec/gcc/i686-pc-linux-gnu/4.1.1/cc1plus -E -quiet -v
-D_GNU_SOURCE bug.cpp -mtune=pentiumpro -Wall -W -Wundef -Wpointer-arith
-fworking-directory -O0 -fpch-preprocess -o bug.ii
ignoring nonexistent directory "NONE/include"
ignoring nonexistent directory
"/usr/local/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../../i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../../include/c++/4.1.1

/usr/local/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../../include/c++/4.1.1/i686-pc-linux-gnu

/usr/local/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../../include/c++/4.1.1/backward
 /usr/local/include
 /usr/local/lib/gcc/i686-pc-linux-gnu/4.1.1/include
 /usr/include
End of search list.
 /usr/local/libexec/gcc/i686-pc-linux-gnu/4.1.1/cc1plus -fpreprocessed bug.ii
-quiet -dumpbase bug.cpp -mtune=pentiumpro -auxbase-strip /dev/null -g -O0
-Wall -W -Wundef -Wpointer-arith -version -o bug.s
GNU C++ version 4.1.1 (i686-pc-linux-gnu)
        compiled by GNU C version 4.1.1.
GGC heuristics: --param ggc-min-expand=63 --param ggc-min-heapsize=63424
Compiler executable checksum: 5c1ee95ea2451a4e1aafd30c10a207cb
bug.cpp: In function 'void inner() [with _Wrapper = TraitedWrapper, _Type =
Generated]':
bug.cpp:101:   instantiated from here
bug.cpp:79: internal compiler error: in stabilize_call, at cp/tree.c:2248
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


-- 
           Summary: ICE on throwing copy of object returned by reference
                    from method with traits-deduced return-type
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: raymond at corvil dot com
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33012

[Bug c++/33012] ICE on throwing copy of object returned by reference from method with traits-deduced return-type

[raymond at corvil dot com]

------- Comment #1 from raymond at corvil dot com  2007-08-07 17:59 -------
I have been able to reproduce the same ICE in 3.4.2,

    gcc version 3.4.2 20040827 (prerelease) [FreeBSD]

but not in 2.95.4 or 4.1.2:

    gcc version 2.95.4 20020320 [FreeBSD]
    gcc version 4.1.2 (Ubuntu 4.1.2-0ubuntu4)


I originally found the ICE in some code that was throwing a copy of an object
in a std::vector on the stack.  By playing around with the test code I posted,
I found that it seems to trigger only when the following three conditions occur
together:

* the copy is directly thrown, and not when the a copy is declared on the stack
and then thrown;
* the method that provides the reference to be copied has a return-type deduced
from a traits template;
* the class of the object being thrown does not provide a copy-constructor.

I've tried to illustrate in the full test case that, if any one of these
conditions is false, then the ICE doesn't happen.


The following shorter test-case also triggers the error.  I know it includes a
standard header, and I haven't provided pre-processed sources for this, but
it's just for illustration purposes.

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
#include <vector>

/*
 * inner() throws a copy of an object contained in a vector.
 * It's templated to show what happens with different _Types.
 */

template<typename _Type>
void    inner()
{
        typename std::vector<_Type> vector(1);
        throw _Type(*vector.begin());
}


struct Generated { };

struct Manual {
        Manual() { }
        Manual(const Manual&) { }
};


void    outer()
{
// No problems when the class has a hand-written copy-constructor:
        inner<Manual>();

// ICE when the class has a compiler-supplied copy-constructor:
        inner<Generated>();
}

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33012

[Bug c++/33012] ICE on throwing copy of object returned by reference from method with traits-deduced return-type

[pcarlini at suse dot de]

------- Comment #2 from pcarlini at suse dot de  2007-08-15 09:14 -------
So the problem is already fixed in all the active branches. Thanks, anyway!


-- 

pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
      Known to work|                            |4.1.2 4.2.1 4.3.0
         Resolution|                            |WORKSFORME


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33012

[Bug c++/33012] ICE on throwing copy of object returned by reference from method with traits-deduced return-type

[raymond at corvil dot com]

------- Comment #3 from raymond at corvil dot com  2007-08-16 09:50 -------
Yes, it does not happen with recent releases.  I logged it because I couldn't
find any hint of this problem having been seen and noted anywhere.  I just
wanted to let you know about it in case the problem has simply been masked by
recent code changes rather than specifically fixed (not that I'm suggesting it
has ;-) I just don't know).  Thanks!


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33012