patch 8.2.3566: build failure on old systems when using nano timestamp
Problem: Build failure on old systems when using nano timestamp.
Solution: Define _BSD_SOURCE, _SVID_SOURCE and _DEFAULT_SOURCE. (Gary
Johnson, closes #9054)
diff --git a/src/vim.h b/src/vim.h
index 31d4bde..43fb8e0 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -43,6 +43,21 @@
// 700 is needed for mkdtemp().
# ifndef _XOPEN_SOURCE
# define _XOPEN_SOURCE 700
+
+// On old systems, defining _XOPEN_SOURCE causes _BSD_SOURCE, _SVID_SOURCE
+// and/or // _DEFAULT_SOURCE not to be defined, so do that here. Those are
+// needed to include nanosecond-resolution timestamps in struct stat. On new
+// systems, _DEFAULT_SOURCE is needed to avoid warning messages about using
+// deprecated _BSD_SOURCE or _SVID_SOURCE.
+# ifndef _BSD_SOURCE
+# define _BSD_SOURCE 1
+# endif
+# ifndef _SVID_SOURCE
+# define _SVID_SOURCE 1
+# endif
+# ifndef _DEFAULT_SOURCE
+# define _DEFAULT_SOURCE 1
+# endif
# endif
# endif