[Bug c++/56901] New: [4.9 regression] lambda with implicit capture by reference

[zeratul976 at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56901



             Bug #: 56901

           Summary: [4.9 regression] lambda with implicit capture by

                    reference

    Classification: Unclassified

           Product: gcc

           Version: 4.9.0

            Status: UNCONFIRMED

          Severity: normal

          Priority: P3

         Component: c++

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: zeratul...@hotmail.com





The following code compiles with gcc 4.8 and clang, but not with gcc 4.9:





template <typename>

void foo_impl()

{

    int data;

    auto L = [&](){ return data; };

    [&](){ L(); }();

}



void foo()

{

    foo_impl<int>();

}





The error is:





test.cpp: In instantiation of 'foo_impl() [with <template-parameter-1-1> =

int]::__lambda1':

test.cpp:6:12:   required from 'struct foo_impl() [with

<template-parameter-1-1> = int]::__lambda1'

test.cpp:6:19:   required from 'void foo_impl() [with <template-parameter-1-1>

= int]'

test.cpp:11:19:   required from here

test.cpp:5:14: error: uninitialized const member 'foo_impl() [with

<template-parameter-1-1> = int]::__lambda0::__data'

     auto L = [&](){ return data; };

              ^





The error goes away if:

  - foo_impl is made a nontemplate

  - the call to the second lambda is inlined

  - either lambda is made to capture by value instead of reference