C++ runtime shared library build needs ANTLR4CPP_EXPORTS to be defined but is not

[adrpo]

You can in general do:
cmake -DCMAKE_CXX_FLAGS:STRING=-DANTLR4CPP_EXPORTS
to fix this but maybe one should assume that by default this should be defined if you build the shared library. If you don't define it then the assumption is (at least on Windows:
#define ANTLR4CPP_PUBLIC __declspec(dllimport)
which generates errors if you try to compile the C++ files with MinGW g++.

[adrpo]

Should be fixed by PR: #1548

[adrpo]

also make install will fail because it wants to install License.txt which does not exist :)
https://github.com/antlr/antlr4/blob/master/runtime/Cpp/CMakeLists.txt#L110

[adrpo]

Fixed by PR: #1548.