replaced SCUMMVM_VERSION/SCUMMVM_CVS by gScummVMVersion/gScummVMBuildDate/gScummVMFullVersion; made engine.o depend on all other .o files, so that the build date in it is always up-to-date

svn-id: r9032

common/engine.cpp

@@ -25,6 +25,49 @@
 #include "timer.h"
 #include "sound/mixer.h"
 
+/*
+ * Version string and build date string. These can be used by anything that
+ * wants to display this information to the user (e.g. about dialog).
+ *
+ * Note: it would be very nice if we could instead of (or in addition to) the
+ * build date present a date which corresponds to the date our source files
+ * were last changed. To understand the difference, imagine that a user
+ * makes a checkout of CVS on January 1, then after a week compiles it
+ * (e.g. after doing a 'make clean'). The build date then will say January 8
+ * even though the files were last changed on January 1.
+ *
+ * Another problem is that __DATE__/__TIME__ depend on the local time zone.
+ *
+ * It's clear that such a "last changed" date would be much more useful to us
+ * for feedback purposes. After all, when somebody files a bug report, we
+ * don't care about the build date, we want to know which date their checkout
+ * was made. This is even more important now since anon CVS lags a few
+ * days behind developer CVS.
+ *
+ * So, how could we implement this? At least on unix systems, a special script
+ * could do it. Basically, that script would run over all .cpp/.h files and
+ * parse the CVS 'Header' keyword we have in our file headers.
+ * That line contains a date/time in GMT. Now, the script just has to collect
+ * all these times and find the latest. This time then would be inserted into
+ * a header file or so (common/date.h ?) which engine.cpp then could
+ * include and put into a global variable analog to gScummVMBuildDate.
+ *
+ * Drawback: scanning all source/header files will be rather slow. Also, this
+ * only works on systems which can run powerful enough scripts (so I guess
+ * Visual C++ would be out of the game here? don't know VC enough to be sure).
+ *
+ * Another approach would be to somehow get CVS to update a global file
+ * (e.g. LAST_CHANGED) whenever any checkins are made. That would be
+ * faster and work w/o much "logic" on the client side, in particular no
+ * scripts have to be run. The problem with this is that I am not even
+ * sure it's actually possible! Modifying files during commit time is trivial
+ * to setup, but I have no idea if/how one can also change files which are not
+ * currently being commit'ed.
+ */
+const char *gScummVMVersion = "0.5.0pre-cvs";
+const char *gScummVMBuildDate = __DATE__ " " __TIME__;
+const char *gScummVMFullVersion = "ScummVM 0.5.0pre-cvs (" __DATE__ " " __TIME__ ")";
+
 /* FIXME - BIG HACK for MidiEmu */
 OSystem *g_system = 0;
 SoundMixer *g_mixer = 0;