Merge pull request #4353 from shuujii/pad-leading-zero-to-month-and-day-in-MRUBY_RELEASE_DATE

Pad leading zero to month and day in `MRUBY_RELEASE_DATE`

include/mruby/version.h

@@ -77,7 +77,21 @@ MRB_BEGIN_DECL
 /*
  * Release date as a string.
  */
-#define MRUBY_RELEASE_DATE MRB_STRINGIZE(MRUBY_RELEASE_YEAR) "-" MRB_STRINGIZE(MRUBY_RELEASE_MONTH) "-" MRB_STRINGIZE(MRUBY_RELEASE_DAY)
+#define MRUBY_RELEASE_DATE    \
+  MRUBY_RELEASE_YEAR_STR "-"  \
+  MRUBY_RELEASE_MONTH_STR "-" \
+  MRUBY_RELEASE_DAY_STR
+#define MRUBY_RELEASE_YEAR_STR MRB_STRINGIZE(MRUBY_RELEASE_YEAR)
+#if MRUBY_RELEASE_MONTH < 10
+#define MRUBY_RELEASE_MONTH_STR "0" MRB_STRINGIZE(MRUBY_RELEASE_MONTH)
+#else
+#define MRUBY_RELEASE_MONTH_STR MRB_STRINGIZE(MRUBY_RELEASE_MONTH)
+#endif
+#if MRUBY_RELEASE_DAY < 10
+#define MRUBY_RELEASE_DAY_STR "0" MRB_STRINGIZE(MRUBY_RELEASE_DAY)
+#else
+#define MRUBY_RELEASE_DAY_STR MRB_STRINGIZE(MRUBY_RELEASE_DAY)
+#endif
 
 /*
  * The year mruby was first created.