scalar-diagnose: use 'git diagnose --mode=all'

Replace implementation of 'scalar diagnose' with an internal invocation of
'git diagnose --mode=all'. This simplifies the implementation of
'cmd_diagnose' by making it a direct alias of 'git diagnose' and removes
some code in 'scalar.c' that is duplicated in 'builtin/diagnose.c'. The
simplicity of the alias also sets up a clean deprecation path for 'scalar
diagnose' (in favor of 'git diagnose'), if that is desired in the future.

This introduces one minor change to the output of 'scalar diagnose', which
is that the prefix of the created zip archive is changed from 'scalar_' to
'git-diagnostics-'.

Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Victoria Dye <vdye@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/scalar/scalar.c

@@ -11,7 +11,6 @@
 #include "dir.h"
 #include "packfile.h"
 #include "help.h"
-#include "diagnose.h"
 
 /*
  * Remove the deepest subdirectory in the provided path string. Path must not
@@ -510,34 +509,19 @@ static int cmd_diagnose(int argc, const char **argv)
 		N_("scalar diagnose [<enlistment>]"),
 		NULL
 	};
-	struct strbuf zip_path = STRBUF_INIT;
-	time_t now = time(NULL);
-	struct tm tm;
+	struct strbuf diagnostics_root = STRBUF_INIT;
 	int res = 0;
 
 	argc = parse_options(argc, argv, NULL, options,
 			     usage, 0);
 
-	setup_enlistment_directory(argc, argv, usage, options, &zip_path);
-
-	strbuf_addstr(&zip_path, "/.scalarDiagnostics/scalar_");
-	strbuf_addftime(&zip_path,
-			"%Y%m%d_%H%M%S", localtime_r(&now, &tm), 0, 0);
-	strbuf_addstr(&zip_path, ".zip");
-	switch (safe_create_leading_directories(zip_path.buf)) {
-	case SCLD_EXISTS:
-	case SCLD_OK:
-		break;
-	default:
-		error_errno(_("could not create directory for '%s'"),
-			    zip_path.buf);
-		goto diagnose_cleanup;
-	}
+	setup_enlistment_directory(argc, argv, usage, options, &diagnostics_root);
+	strbuf_addstr(&diagnostics_root, "/.scalarDiagnostics");
 
-	res = create_diagnostics_archive(&zip_path, DIAGNOSE_ALL);
+	res = run_git("diagnose", "--mode=all", "-s", "%Y%m%d_%H%M%S",
+		      "-o", diagnostics_root.buf, NULL);
 
-diagnose_cleanup:
-	strbuf_release(&zip_path);
+	strbuf_release(&diagnostics_root);
 	return res;
 }