The GNU C compiler apparently still permits this, and the VC++ 2005 compiler permits it too, though it issues a Level-4 warning if it’s C code, and a Level-2 warning if it’s C++ code.
W. Lavrijsen, and A. Dutta. Proceedings of the 6th Workshop on Python for High-Performance and Scientific Computing, page 27--35. Piscataway, NJ, USA, IEEE Press, (2016)