Implicit typing and backwards compatibility

[epagone]

@whuhn

My $0.02 is that removing “implicit save” would cause difficult-to-debug runtime errors whose resolution wouldn’t make the code that much cleaner, whereas enforcing “implicit none” by default for modern Fortran would lead to relatively easy-to-spot compiler-time errors whose resolution would make the code cleaner.

As mentioned by others before, compiler vendors could provide specific flags for legacy code to maintain “implicit save”.

A counter-argument to give higher priority to the removal of “implicit save” over the default “implicit none” is that “here and now” we can already use compiler flags to turn on “implicit none” with (all?) compilers whereas I am not aware of any compiler flag to remove “implicit save”. Thus, the standard committee might help provide such feature.