c++11 std::unique_ptr error cmake 3.11.3 bootstrap - c++11

Question

I am trying to bootstrap cmake 3.11.3 on Ubuntu 16.04.4 LTS xenial.
I have upgrade my gnu g++ compiler as follows:
> $ g++ --version
g++ (Ubuntu 8.1.0-5ubuntu1~16.04) 8.1.0 Copyright (C) 2018 Free
Software Foundation, Inc. This is free software; see the source for
copying conditions. There is NO warranty; not even for MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.
And manually re-pointed the symbolic links:
$ ll /usr/bin/*g++*
lrwxrwxrwx 1 root root 5 Jun 8 16:57 /usr/bin/g++ -> g++-8*
-rwxr-xr-x 1 root root 919832 Apr 24 15:02 /usr/bin/g++-5*
lrwxrwxrwx 1 root root 22 Jun 6 04:26 /usr/bin/g++-8 -> x86_64-linux-gnu-g++-8*
lrwxrwxrwx 1 root root 22 Jun 8 16:58 /usr/bin/x86_64-linux-gnu-g++ -> x86_64-linux-gnu-g++-8*
lrwxrwxrwx 1 root root 5 Apr 24 15:02 /usr/bin/x86_64-linux-gnu-g++-5 -> g++-5*
-rwxr-xr-x 1 root root 1071984 Jun 6 04:26 /usr/bin/x86_64-linux-gnu-g++-8*
However, I get the following error in the configuration of cmake:
$ sudo ./bootstrap
---------------------------------------------
CMake 3.11.3, Copyright 2000-2018 Kitware, Inc. and Contributors
Found GNU toolchain
C compiler on this system is: gcc
C++ compiler on this system is: g++
Makefile processor on this system is: make
g++ has setenv
g++ has unsetenv
g++ does not have environ in stdlib.h
g++ has stl wstring
g++ has <ext/stdio_filebuf.h>
---------------------------------------------
make: Warning: File 'Makefile' has modification time 2.3 s in the future
make: 'cmake' is up to date.
make: warning: Clock skew detected. Your build may be incomplete.
loading initial cache file /mnt/ganymede/user/gpeytavi/srv_admin/software/cmake-3.11.3/Bootstrap.cmk/InitialCacheFlags.cmake
CMake Error at CMakeLists.txt:92 (message):
The C++ compiler does not support C++11 (e.g. std::unique_ptr).
-- Configuring incomplete, errors occurred!
See also "/mnt/ganymede/user/gpeytavi/srv_admin/software/cmake-3.11.3/CMakeFiles/CMakeOutput.log".
See also "/mnt/ganymede/user/gpeytavi/srv_admin/software/cmake-3.11.3/CMakeFiles/CMakeError.log".
---------------------------------------------
Error when bootstrapping CMake:
Problem while running initial CMake
---------------------------------------------
Any idea why I get a c++11 std::unique_ptr non-compliant error?

Answer 1

In my case, the issue is because of the folder where I have CMake source code is in a mounted directory (in fact my entire rootfs is mounted over NFS)
So, I looked in 'mount' command output and selected '/run/user/1000' location as a local location as this is mounted using tmpfs and moved my CMake source code to this location.
with this, ./bootstrap && make && sudo make install executed successfully.

Answer 2

Actually the ./bootstrap script does try the different C++ standard flags with the compiler. So it should detect its capabilities automatically.
Please make sure you don't have any CXXFLAGS environment variable set and try from scratch again (the messages/warnings you get indicate several tries/errors in the same directory).
Output when Successful
As a reference on my Ubuntu calling CMake's ./bootstrap looks like this:
---------------------------------------------
CMake 3.11.20180423, Copyright 2000-2018 Kitware, Inc. and Contributors
Warning: This is an in-source build
Found GNU toolchain
C compiler on this system is: gcc
C++ compiler on this system is: g++ -std=gnu++1y
Makefile processor on this system is: make
g++ has setenv
g++ has unsetenv
g++ does not have environ in stdlib.h
g++ has stl wstring
g++ has <ext/stdio_filebuf.h>
---------------------------------------------
Debugging
For debugging your problem you also could:
Call ./bootstrap --verbose
Look into Bootstrap.cmk/cmake_bootstrap.log
Known Problem
I only once had a problem with bootstrap using clang compilers where I needed to do the following call:
export CXXFLAGS=-Xclang -std=c++1z -Xclang -stdlib=libc++
Alternative
If you just want to install the latest version see How to specify where CMake is installed in Ubuntu?

Answer 3

I was able to resolve the issue by ensuring that both the build machine and the NFS file server were synchronized by running ntpd on both.

Answer 4

For me it was clock skew. I use the below command :
date -s "2021-11-30 15:08:21"
to set the time to now for the server. Then it work, thanks...