Explicit recompilation required to change compilation options
When you recompile without modifying any source code, nothing happens, as expected. The file is already compiled, after all. If you then change compilation options, such as adding the
-O2 flag, it still doesn't recompile, even though the program might now be expected to behave or perform differently. Users can work around this using
-fforce-recomp, but perhaps they shouldn't have to, or perhaps they should be warned that this may be necessary. One option might be to record "significant" compilation options in the
.hi file, to determine whether they have changed in a way that suggests recompilation may be in order.