Some versions of MacOS will start automatically combining "diacritical" characters
with whatever you type after them.  This makes chars line ' or ^ or ~ impossible
to type in to any program.  C, vi(m), perl, ABC tools, etc. become unusable, since
they all use such chars as part of their languages. For example C (like many other
programming languages) uses 'a' to name that single character as a data object.
This bug rewrites 'a' as à', which is a fatal syntax error.

The culprit seems to be the thing called "us international" in the settings.  one
version of the instructions for fixing it is:

1. Go to system preferences > keyboard > input sources
2. Remove the item called us international pc, leaving only us or abc on the list

I found his on apple.stackexchange.com, which has a number of questions from folks
hit by this problem.  You don't need to be actually using the setting mentioned;
it seems to cause the problem even if you were using a different keyboard scheme.
You need to remove it from your list of "enabled" keyboards.

Encountered: 2022-11-14.