[Bug c++/15231] New: Local variables in lambdas are not accessible

[Bug c++/15231] New: Local variables in lambdas are not accessible

[poenitz at htwm dot de]

http://sourceware.org/bugzilla/show_bug.cgi?id=15231

             Bug #: 15231
           Summary: Local variables in lambdas are not accessible
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned@sourceware.org
        ReportedBy: poenitz@htwm.de
    Classification: Unclassified


The local variable x does not seem to be "visible" for the debugger in the
following:


echo "
    void breaker() {}
    struct Z
    {
        int b;

        Z() {
            auto a = [&]() {
                int x = 32;
                breaker();
                return x;
            };
            b = a();
        }

    };

    int main()
    {
        Z z;
        return z.b;
    }
" | g++ -g -xc++ -std=c++11 -


gdb -ex 'b breaker' -ex 'run' -ex 'up' -ex 'p x' -ex 'bt full' ./a.out



->   GNU gdb (GDB) 7.5.50.20121013-cvs
->   [...]

->    10      in <stdin>
->    No symbol "x" in current context.


->    #0  breaker () at <stdin>:2
->    No locals.
->    #1  0x0804840e in Z::Z()::{lambda()#1}::operator()() const () at
->    <stdin>:10
->    No locals.
->    #2  0x08048425 in Z::Z (this=0xbffff34c) at <stdin>:13
->            a = {<No data fields>}
->    #3  0x080483f6 in main () at <stdin>:20
->            z = {b = -1208270848}


$ gcc --version
gcc (Ubuntu/Linaro 4.7.2-2ubuntu1) 4.7.2
Copyright (C) 2012 Free Software Foundation, Inc.

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[Bug c++/15231] Local variables in lambdas are not accessible

[tromey at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15231

Tom Tromey <tromey at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at redhat dot com

--- Comment #1 from Tom Tromey <tromey at redhat dot com> 2013-03-06 02:42:56 UTC ---
gdb ignores the outer function due to missing PC bounds:

 <1><5a>: Abbrev Number: 8 (DW_TAG_subprogram)
    <5b>   DW_AT_specification: <0x3d>    
    <5f>   DW_AT_inline      : 2    (declared as inline but ignored)
    <60>   DW_AT_object_pointer: <0x68>    
    <64>   DW_AT_sibling     : <0x15c>    

and

  /* Ignore functions with missing or invalid low and high pc attributes.  */
  if (!dwarf2_get_pc_bounds (die, &lowpc, &highpc, cu, NULL))
    {
      attr = dwarf2_attr (die, DW_AT_external, cu);
[...]
      return;

So the lambda's locals are never processed.

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[Bug c++/15231] Local variables in lambdas are not accessible

[cemkalyoncu at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=15231

Cem Kalyoncu <cemkalyoncu at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |cemkalyoncu at gmail dot com

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