CMAKE_CXX_STANDARD=14 leads to -std=c++1y instead of -std=c++14 when compiling ROOT

[lucifer1004]

To reproduce, use the wizard to compile

https://root.cern/download/root_v6.26.06.source.tar.gz

No other dependencies are needed for now.

In srcdir, run the command:

cmake -DCMAKE_INSTALL_PREFIX=$prefix -DCMAKE_TOOLCHAIN_FILE=${CMAKE_TARGET_TOOLCHAIN} -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_STANDARD=14 -Dminimal=ON root-6.26.06

And from the printed information, it can be seen that C++ flag is

-std=c++1y -pipe -Wshadow -Wall -W -Woverloaded-virtual -fsigned-char -pthread -O3 -DNDEBUG

But when I did this on my local system (Ubuntu 22.04), the flag is

-std=c++14 -pipe -Wshadow -Wall -W -Woverloaded-virtual -fsigned-char -pthread -O3 -DNDEBUG

So I think there is something wrong with the environment provided by BinaryBuilder. But currently, I do not know the root cause of this.

[lucifer1004]

Also, it seems that CXX_STANDARD above 14 is not supported yet in the sandbox.

[giordano]

Use a version of GCC which actually supports the C++14 standard? See https://gcc.gnu.org/projects/cxx-status.html#cxx14

[lucifer1004]

So this should be solved with preferred_gcc_version option?

[lucifer1004]

How should I do this in wizard mode?

[giordano]

So this should be solved with preferred_gcc_version option?

Yes

How should I do this in wizard mode?

When you're asked "Do you want to customize the set of compilers?" you have to answer yes:

BinaryBuilder.jl/src/wizard/obtain_source.jl

Line 382 in c3ab910

if yn_prompt(state, "Do you want to customize the set of compilers?", :n) == :y

[lucifer1004]

Thanks!

[lucifer1004]

I have never used that option before.