Okay, I have reviewed the project settings and switches and such, and the only difference I can find between the invocation in eclipse and CodeBlocks is the following. In eclipse, it compiles with the gcc compiler, but the actual invocation is "g++" instead of "gcc". My understanding is "gcc" invokes "g++" anyway, but in CodeBlocks, I see no way to *force* the invocation of g++. Instead, CodeBlocks gives me a pulldown list of compilers to choose from, gcc being one of the choices. But I see nowhere to force CodeBlocks to invoke g++ versus gcc (or otherwise make the whatever distinctions the g++ invocation might have.
While my common sense says, "it can't be this", I cannot find other differences. One reason this seems like it is not the answer is what causes the problem, namely the "glee.h/glee.c" files... which are C, not C++. In contrast, all my files are ".h/.cpp" files (without classes or templates or function overloading, however), which compile okay. So, on the surface anyway, it seems that a C program is causing the problem, not C++. But what do I know? Obviously, not enough.