[Documantation] Invalid C++ compiler version stated in GetStartedGuide.md

[artemrad]

Describe the bug
The GetStartedGuide.md states that the minimal perquisite C++ compiler required to compile the project from source is the same compiler as host compiler toolchain requirements, which states gcc 7.1.

Compiling the project with gcc 7.2.0 produces weird errors such as the one below...

[113/3063] Building CXX object lib/Support/CMakeFiles/LLVMSupport.dir/Process.cpp.o
FAILED: lib/Support/CMakeFiles/LLVMSupport.dir/Process.cpp.o 
/p/psg/ctools/gcc/7.2.0/1/linux64/bin/g++ -DENABLE_OPAQUE_POINTERS=1 -DGTEST_HAS_RTTI=0 -D_DEBUG -D_GLIBCXX_ASSERTIONS -D_GNU_SOURCE -D_LIBCPP_ENABLE_ASSERTIONS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/nfs/site/disks/swuser_work_aradzikh/external/llvm-intel/build/lib/Support -I/nfs/site/disks/swuser_work_aradzikh/external/llvm-intel/llvm/lib/Support -I/nfs/site/disks/swuser_work_aradzikh/external/llvm-intel/build/include -I/nfs/site/disks/swuser_work_aradzikh/external/llvm-intel/llvm/include -fPIC -fno-semantic-interposition -fvisibility-inlines-hidden -Werror=date-time -fno-lifetime-dse -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wno-missing-field-initializers -pedantic -Wno-long-long -Wimplicit-fallthrough -Wno-maybe-uninitialized -Wno-noexcept-type -Wdelete-non-virtual-dtor -Wno-comment -Wno-misleading-indentation -fdiagnostics-color -ffunction-sections -fdata-sections -O3 -DNDEBUG -std=c++1z -UNDEBUG  -fno-exceptions -funwind-tables -fno-rtti -MD -MT lib/Support/CMakeFiles/LLVMSupport.dir/Process.cpp.o -MF lib/Support/CMakeFiles/LLVMSupport.dir/Process.cpp.o.d -o lib/Support/CMakeFiles/LLVMSupport.dir/Process.cpp.o -c /nfs/site/disks/swuser_work_aradzikh/external/llvm-intel/llvm/lib/Support/Process.cpp
In file included from /nfs/site/disks/swuser_work_aradzikh/external/llvm-intel/llvm/lib/Support/Process.cpp:107:0:
/nfs/site/disks/swuser_work_aradzikh/external/llvm-intel/llvm/lib/Support/Unix/Process.inc: In static member function ‘static std::error_code llvm::sys::Process::FixupStandardFileDescriptors()’:
/nfs/site/disks/swuser_work_aradzikh/external/llvm-intel/llvm/lib/Support/Unix/Process.inc:211:54: error: invalid initialization of reference of type ‘int (&)(int, stat*) noexcept’ from expression of type ‘int(int, stat*) noexcept’
     if (RetryAfterSignal(-1, ::fstat, StandardFD, &st) < 0) {

Compiling with gcc 12.2.0 does not produce any of these errors. Where in between the two versions is the actual minimal supported compiler, I do not know, but the one that is documented is definitely wrong.

Please also add into the instructions on how to specify the path to the C++ compiler, if it doesn't happen to be in the default OS location. I had to modify the buildbot/configure.py file to add the following lines, in order to convince cmake to use the right compiler.

        "-DCMAKE_C_COMPILER=/p/psg/ctools/gcc/12.2.0/3/linux64/suse12/bin/gcc",
        "-DCMAKE_CXX_COMPILER=/p/psg/ctools/gcc/12.2.0/3/linux64/suse12/bin/g++",

Thank you :)

[bader]

The GetStartedGuide.md states that the minimal perquisite C++ compiler required to compile the project from source is the same compiler as host compiler toolchain requirements, which states gcc 7.1.

@artemrad the statement is still correct. You found a bug in llvm-project, which is not related to SYCL. It was also discussed here: https://discourse.llvm.org/t/require-gcc-7-4-as-gcc-7-3-cannot-build-llvm-16-x-or-main/72310 and fixed by 1e06b82. This commit will be merged to the sycl branch with #10783.

[bader]

Please also add into the instructions on how to specify the path to the C++ compiler, if it doesn't happen to be in the default OS location. I had to modify the buildbot/configure.py file to add the following lines, in order to convince cmake to use the right compiler.

        "-DCMAKE_C_COMPILER=/p/psg/ctools/gcc/12.2.0/3/linux64/suse12/bin/gcc",
        "-DCMAKE_CXX_COMPILER=/p/psg/ctools/gcc/12.2.0/3/linux64/suse12/bin/g++",

You can pass addition CMake options via

  --cmake-opt CMAKE_OPT
                        Additional CMake option not configured via script parameters

For example: add following options to configure.py script --cmake-opt=-DCMAKE_C_COMPILER=/p/psg/ctools/gcc/12.2.0/3/linux64/suse12/bin/gcc --cmake-opt=-DCMAKE_CXX_COMPILER=/p/psg/ctools/gcc/12.2.0/3/linux64/suse12/bin/g++.