I sometimes have issues with the incremental rebuild on visual C++ (2003 currently ). Some dependencies does not seem correctly checked and some files aren't build when they should. I suppose thoses issues come from the timestamp approach to incremental rebuild.
I don't consider it a huge issue when building debug build on my desk, however for distribuable build this is a issue.
Is it safe to use incremental build for a build server or is a full build a requirement ?
Binaries built using with the incremental build feature are going to be bigger and slower, even for release builds, because they necessarily contain scaffolding to enable the incremental builds that isn't necessary for fully optimized builds. I'd recommend you not to use incremental builds for this reason.
You need a build you distrubute to be recreatable again should users experience problems that need investigating.
I would not rely on an incremental build. Also, I would always delete all source from the build machine, and fetch it from scratch from the source control system before building a release. This way, you know you can repeat the build process again by fetching the same source code.
If you use an incremental build, the build will build differently each time because only a subset of the system will need to be built. I think its just good to eliminate as many possible differences between release builds as possible. So, for this reason incremental builds are out.
It's a good idea to label or somehow mark the versions of each source file in the source control system with the version number of the build. This enables you to keep track of the exact source that went into building the release. With a decent source code control system the labels can be used to track down all the changes that were made to the code between one release and the next. This can be a real help when trying to track down a bug that you know was introduced between the two releases.
Incremental builds can still be useful on a development machine when you're not distributing the build, just for saving time during the code/debug/test/repeat development cycle.
I would always prefer to do a full clean and rebuild for any release for peace of mind if nothing else. Assuming that you're talking about externally released builds and not just builds using the Release configuration, the fact that these builds are relatively infrequent means that any time saving will be minimal in the long run.
I'd argue that you should avoid the "is it safe" question. It's simply not worth looking into.
The advantage of incremental builds is the cost saving. Small per build, it adds up for all the debug builds a developer typically makes, and then adds up further for all developers on your team.
On the other hand, release builds are rare. The costs of a release build are not in developers waiting on them, they're found much more in the team of testers that need to validate it.
For that reason, I find that incremental builds are without a doubt cost-saving for debug builds, but I refuse to spend any time calculating the small saving I'd get out of incrementally building a release build.