[Bug c++/57408] New: lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327

[Bug c++/57408] New: lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327

[superbem at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57408

            Bug ID: 57408
           Summary: lambda, Variable length arrays, thread, internal
                    compiler error: in expand_expr_real_1, at expr.c:9327
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: superbem at gmail dot com

#include <thread>
#include <cstdio>
using namespace std;

int main(){
    int y=2;
    float fa[2][y]; // thread compile fine if y were 2 hardcoded instead
    fa[0][0]=0.8;
    fa[0][1]=1.8;
    auto fx=[&](){
        for(int c=0;c<2;c++){ // thread compile fine if c<2 were c<1 instead
            printf("\n%f",fa[0][c]); // (1*) "internal compiler error: in
expand_expr_real_1, at expr.c:9327"
        }
    };
    fx(); // works fine everytime
    thread(fx).join(); //error (1*)
}

[Bug c++/57408] lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57408

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
I'm not at all sure this is a C++ front-end issue.

[Bug c++/57408] lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57408

Daniel Krügler <daniel.kruegler at googlemail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |daniel.kruegler@googlemail.
                   |                            |com

--- Comment #2 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
First attempt so simplify (and to get rid of some library dependencies):

//---------------------------------
#include <functional>

struct Impl_base
{
  virtual ~Impl_base(){}
  virtual void run() = 0;
};

template<typename Callable>
  struct Impl : public Impl_base
  {
    Callable func;
    Impl(Callable f) : func(f) { }
    void run() { func(); }
  };

template<typename Callable>
  void
  make_routine(Callable&& f)
  {
    new Impl<Callable>(static_cast<Callable&&>(f));
  }

template<typename Callable>
void make(Callable&& f)
  {
    make_routine(std::__bind_simple(f));
  }

extern void use(float);

int main(){
    int y = 2;
    float fa[2][y]; // compiles fine if y were 2 hard-coded instead
    fa[0][0]=0.8;
    fa[0][1]=1.8;
    auto fx=[&](){
        for(int c=0; c<2; c++){ // compiles fine if c<2 were c<1 instead
            use(fa[0][c]);
        }
    };
    make(fx); //error (1*)
}
//---------------------------------

causes the same error (using gcc 4.9.0 20130519 (experimental)):

"main.cpp||In function 'int main()':|
main.cpp|34|warning: ISO C++ forbids variable length array 'fa' [-Wvla]|
main.cpp||In member function 'void Impl<Callable>::run() [with Callable =
std::_Bind_simple<main()::<lambda()>()>]':|
main.cpp|39|warning: '<anonymous>' is used uninitialized in this function
[-Wuninitialized]|
|34|note: '<anonymous>' was declared here|
main.cpp|39|internal compiler error: in expand_expr_real_1, at expr.c:9361|
"
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Subject: [Bug c++/57408] lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327
Date: Sat, 25 May 2013 13:37:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57408

--- Comment #3 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
Further simplification down to a library-free test case:

//------------------------------------------------------
template<typename Callable>
  struct Impl
  {
    Callable func;
    Impl(Callable f) : func(f) { }
    virtual void run() { func(); }
  };

template<typename Callable>
void call(Callable f)
  {
    Impl<Callable>(f).run();
  }

extern "C" int printf(const char*, ...);

int main(){
    int y = 2;
    float fa[2][y]; // compiles fine if y were 2 hard-coded instead
    fa[0][0]=0.8;
    fa[0][1]=1.8;
    auto fx=[&](){
        for(int c=0; c<2; c++){ // compiles fine if c<2 were c<1 instead
            printf("use me", fa[0][c]);
        }
    };
    call(fx); //error (1*)
}
//------------------------------------------------------

It seems relevant, that there is a virtual function that invokes the lambda
closure and that fa[0][c] is odr-used within the closure call expression.
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Subject: [Bug c++/57415] New: [4.9 Regression] New PPC testsuite failure C++ compound literarl expr unimplemented
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idW415

            Bug ID: 57415
           Summary: [4.9 Regression] New PPC testsuite failure C++
                    compound literarl expr unimplemented
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dje at gcc dot gnu.org

/tmp/20130524/gcc/testsuite/g++2/../../xg++
-B/tmp/20130524/gcc/testsuite/g++2/../../
/nasfarm/dje/src/src/gcc/testsuite/g++.dg/ext/altivec-cell-2.C
-fno-diagnostics-show-caret -fdiagnostics-color=never  -nostdinc++
-I/tmp/20130524/powerpc-ibm-aix7.1.0.0/libstdc++-v3/include/powerpc-ibm-aix7.1.0.0
-I/tmp/20130524/powerpc-ibm-aix7.1.0.0/libstdc++-v3/include
-I/nasfarm/dje/src/src/libstdc++-v3/libsupc++
-I/nasfarm/dje/src/src/libstdc++-v3/include/backward
-I/nasfarm/dje/src/src/libstdc++-v3/testsuite/util -fmessage-length=0
-std=gnu++98 -maltivec  -S  -o altivec-cell-2.s    (timeout = 300)
/nasfarm/dje/src/src/gcc/testsuite/g++.dg/ext/altivec-cell-2.C: In function
'int
 g(__vector(8) short int, int)':
/nasfarm/dje/src/src/gcc/testsuite/g++.dg/ext/altivec-cell-2.C:41:27: sorry,
unimplemented: unexpected AST of kind compound_literal_expr
/nasfarm/dje/src/src/gcc/testsuite/g++.dg/ext/altivec-cell-2.C:41:27: internal
compiler error: in potential_constant_expression_1, at cp/semantics.c:8936

[Bug c++/57408] lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327

[superbem at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57408

--- Comment #4 from superbem at gmail dot com ---
Thanks for further testing it.
Isn't this confirmed yet? How to do.
I've stumbled across this issue several times, and I'm very admired that I'm
the only one.

[Bug c++/57408] lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57408

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-06-20
     Ever confirmed|0                           |1

[Bug c++/57408] lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57408

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|superbem at gmail dot com          |jason at gcc dot gnu.org

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Jason, at first I thought this one could be a Dup of 55149 but I'm still seeing
it today.

[Bug c++/57408] lambda, Variable length arrays, thread, internal compiler error: in expand_expr_real_1, at expr.c:9327

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57408

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-invalid-code
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
The issue here is that this capture is not valid C++1y because an array bound
other than the first one is non-constant.  Current 4.9 gives an error and then
crashes; I'll fix the crash, but it will still be rejected.