On Fri, 11 Jun 2021, 21:31 Mehdi Megherbi via Gcc-help, < gcc-help@xxxxxxxxxxx> wrote: > > On Fri, 11 Jun 2021 at 10:17, Mehdi Megherbi via Gcc-help < > gcc-help@xxxxxxxxxxx<mailto:gcc-help@xxxxxxxxxxx>> wrote: > > > > > > > > Hi > > > > > > > > I'm using ubuntu 20.04 and his default gcc version (9.3.0), with > standard C++14 as default. I have to compile from source a lot of > scientific toolkits, all made with C++11. After a lot of research I was not > able to find a way to select the default standard of g++/gcc, so cmake/make > take by default the wrong standard and I get always crashs. > > > > > > Crashes? What is crashing? The toolkits you're compiling? GCC? Cmake? > > > Do you just mean it doesn't compile, or is it compiling and then > crashing when you run the software? > > > > > > Most C++11 code will compile without problems using -std=gnu++14, so I'm > not sure what the problem is. > > > > > > >>sorry for not getting more informations, for example with ROOT cern > > > >>toolkit, if you let C++14 it will switch to the beta version of > > > >>ROOT. And Geant4 toolkit also, it creates a lot warnings during > > > >>compilation. Another decisive exemple is NPTOOL, it simply crash > > > >>during compilation, because of the standard So you really mean crash? Or just fails to compile? What errors do you get? > > >There is really no intrensec way to select the default standard used ? > > > > > > No. > > > > > > Some makefiles will respect the CXXFLAGS variable, but not all. > > > > > > A brute force solution would be to create a wrapper script around gcc > and g++ which always adds your preferred -std option and put that script > earlier in your PATH than the real gcc executables: > > > > > > #!/bin/sh > > > exec g++ "$@" -std=gnu++11 > > > > > > >> I'm suposed to write this in .sh file and source it > No, put it in a file called g++ and make it executable, and use that instead of the real g++ file. That will run the compiler with -std=gnu++11
