-Wextra does several extra checks during the compiling. Unfortunately one of the extra check is for unused parameters.
Several functions have unused parameters (mostly the WrenVM* vm).
If wrenFreeVm was called twice, this would lead to an error, because the memory was allready freed.
The used check is rather naive, suggesting that a valid vm does have at least one methodName set.
Previously, just the static libraries (libwren*.a) were created. In the Makefile documentation these were mentioned in the comments as shared.
Now both variants will be created.
Peter Reijnders