https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79180
Bug ID: 79180
Summary: Nested lambda-capture causes segfault for parameter
pack
Product: gcc
Version: 6.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: markus at dreseler dot de
Target Milestone: ---
Created attachment 40561
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40561&action=edit
Preprocessed file
The following code compiles but prints garbage and then segfaults under gcc
6.3.0 on OS X:
#include <iostream>
#include <string>
void foo(const std::string &a) {
std::cout << a << std::endl;
}
template <typename... Args>
void bar(Args &&... args) {
[&]() {
[&]() {
foo(args...);
}();
}();
}
int main() {
const std::string x("Hello World!");
bar(x);
}
Expected result: Print "Hello World!" and exit.
Compiling with `-Wextra -Wall` gives this warning:
param.cpp: In function 'int main()':
param.cpp:11:11: warning: 'args#0' is used uninitialized in this
function [-Wuninitialized]
foo(args...);
^~~
param.cpp:16:5: note: 'args#0' was declared here
int main() {
^~~~
Clang and VC++ do not have any issues here. People at StackOverflow seem to
agree that this is valid code and appears to be a bug in GCC:
http://stackoverflow.com/questions/41769851/gcc-causes-segfault-for-lambda-captured-parameter-pack
Additional information:
[:~/tmp] 1 $ g++-6 param.cpp && ./a.out
# Garbage here
Segmentation fault: 11
[:~/tmp] 139 $ g++-6 -v
Using built-in specs.
COLLECT_GCC=g++-6
COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc/6.3.0_1/libexec/gcc/x86_64-apple-darwin16.3.0/6.3.0/lto-wrapper
Target: x86_64-apple-darwin16.3.0
Configured with: ../configure --build=x86_64-apple-darwin16.3.0
--prefix=/usr/local/Cellar/gcc/6.3.0_1
--libdir=/usr/local/Cellar/gcc/6.3.0_1/lib/gcc/6
--enable-languages=c,c++,objc,obj-c++,fortran --program-suffix=-6
--with-gmp=/usr/local/opt/gmp --with-mpfr=/usr/local/opt/mpfr
--with-mpc=/usr/local/opt/libmpc --with-isl=/usr/local/opt/isl
--with-system-zlib --enable-libstdcxx-time=yes --enable-stage1-checking
--enable-checking=release --enable-lto --with-build-config=bootstrap-debug
--disable-werror --with-pkgversion='Homebrew GCC 6.3.0_1'
--with-bugurl=https://github.com/Homebrew/homebrew-core/issues --enable-plugin
--disable-nls --enable-multilib
Thread model: posix
gcc version 6.3.0 (Homebrew GCC 6.3.0_1)
[:~/tmp] 1 $ sw_vers
ProductName: Mac OS X
ProductVersion: 10.12.2
BuildVersion: 16C67
