Proposed patches for compile errors on macOS/Clang
The attached patches resolve some compile errors for cetlib code on macOS Sierra (Xcode 8) as of 803ab215.
I believe 0001 and 0002 are valid C++ Standard issue that GCC allows or works around, 0003 I'm not certain about. All tests(*) pass on this platform, but I've not been able to check on Linux yet. Also, the change in 0003 may have implications for upstream clients if it is a Clang issue rather than C++ Standard related.
(*) Plugin tests that use the default search path fail as expected - but these do not use the code touched by the patches.