https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86980
Bug ID: 86980
Summary: Lambda function with return type rvalue reference dtor
issue
Product: gcc
Version: 8.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: neeraj.sharma at alumni dot iitg.ernet.in
Target Milestone: ---
Created attachment 44551
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44551&action=edit
preprocessed file for bug
## Summary
The following code misbehaves as the destructor is called before move ctor (see
the console output further below). I not sure as to what is going wrong here!
// ---
auto f = []() -> Traceable&& {
Traceable tmp;
return std::move(tmp);
};
// compiler will call move ctor here because the
// anonymous function above returns a lvalue
//
// Note: One ctor, one move ctor and two dtor invoked
Traceable a = f();
// x--
## Console output
[0x7ffe7d335ca7] ctor Traceable
[0x7ffe7d335ca7] dtor Traceable
[0x7ffe7d335cd7] move ctor Traceable, &other = 0x7ffe7d335ca7
[0x7ffe7d335cd7] dtor Traceable
## Workaround
If I remove the return type then things work as expected.
// ---
auto f = []() {
Traceable tmp;
return std::move(tmp);
};
// compiler will call move ctor here because the
// anonymous function above returns a lvalue
//
// Note: One ctor, one move ctor and two dtor invoked
Traceable a = f();
// x--
## GCC Version Information
Using built-in specs.
COLLECT_GCC=g++-8
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
8.1.0-5ubuntu1~16.04' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-8
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --with-system-zlib
--with-target-system-zlib --enable-objc-gc=auto --enable-multiarch
--disable-werror --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 8.1.0 (Ubuntu 8.1.0-5ubuntu1~16.04)
## Build Command
g++-8 -save-temps -std=c++17 -Wall -Wextra -g -I include/ -I /usr/local/include
-MP -MMD bug.cpp
Note: No compiler warnings or errors were reported by the above command.
