which may be optionally overridden by version-specific rules.
For example the default rules for gcc on GNU/Linux x86_64 are in the
wmake/rules/linux64Gcc directory. If there is a need to change any of
the rules for a specific version of gcc, e.g. gcc-4.8.4 the directory
wmake/rules/linux64Gcc48 may be created into which any of the language
files may be provided containing the rules to override the defaults.
On 32bit OSs long is not unambiguously int32_t (or int64_t) causing
problems for IO operator resolution. This problem is avoided by
explicitly defining the following operators:
To compile with 64bit labels set
WM_LABEL_SIZE=64
in ~/OpenFOAM/dev/prefs.sh
source ~/.bashrc
then Allwmake in OpenFOAM-dev.
This will build into for example OpenFOAM-dev/platforms/linux64ClangDPInt64Opt
If WM_LABEL_SIZE is unset or set to 32:
WM_LABEL_SIZE=32
the build would be placed into OpenFOAM-dev/platforms/linux64ClangDPInt32Opt
Thus both 32bit and 64bit label builds can coexist without problem.