[Figs]

Actually, that sounds a lot like a bug in your build system. Did you have a custom Makefile (either hand written, or provided by a teacher)? If you didn't keep track of dependencies very carefully so that you always recompile all the .c files that depended on shared .h files when the .h files change, you can wind up with situations where different object files disagree on the layout of structures -- it could cause exactly the sort of problem you describe. Changing the name of the variable could force the file to be recompiled, thus appearing to solve the problem.

[sounds]

To further support your point, the rollback to gcc 2.95 happened across many linux distributions due to incompatible changes in the language that happened at the gcc 3.0 version.

Many distributions rolled back so that the default "stable" compiler matched the one they had to use to build the packages - i.e. common sense.

Once the packages were updated to deal with the gcc 3.x language changes, the compiler and packages started appearing together.

[ArbitraryLimits]

I've seen that problem also (not pretty) but no, the two variables were from the same .c file, and were only used in that file.