I had to install Visual Studio Express for Desktops 2015 since the instructions did not showed that a minimum version and subversion is required but now I reached inside C:\projects\palemoon-source\platform\build\moz.configure\toolchain.configure
CODE:
# Note: We do a strict version check because there sometimes are backwards # incompatible changes in the standard, and not all code that compiles as # C99 compiles as e.g. C11 (as of writing, this is true of libnestegg, for # example) if info.language == 'C' and info.language_version != 199901: if info.type in ('clang-cl', 'clang', 'gcc'): append_flag('-std=gnu99') cxx17_version = 201703 if info.language == 'C++': if info.language_version != cxx17_version: # Compiler doesn't default to C++17, so add the appropriate flag. if info.type in ('clang', 'gcc'): # We're on Clang or GCC, enable C++17 and add GNU extensions. append_flag('-std=gnu++17') else: # We're on MSVC; enable C++17 language mode. append_flag('-std:c++17') # We force clang-cl to emulate Visual C++ 2015 Update 3 with fallback to # cl.exe. if info.type == 'clang-cl' and info.version != '19.00.24213': # Those flags are direct clang-cl flags that don't need -Xclang, add # them directly. flags.append('-fms-compatibility-version=19.00.24213') flags.append('-fallback')