selftests/ftrace: Add test case for synthetic event syntax errors

Add a selftest that verifies that the syntax error messages and caret
positions are correct for most of the possible synthetic event syntax
error cases.

Link: https://lkml.kernel.org/r/af611928ce79f86eaf0af8654f1d7802d5cc21ff.1602598160.git.zanussi@kernel.orgTested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/testing/selftests/ftrace/test.d/trigger/inter-event/trigger-synthetic_event_syntax_errors.tc

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test synthetic_events syntax parser errors
+# requires: synthetic_events error_log
+
+check_error() { # command-with-error-pos-by-^
+    ftrace_errlog_check 'synthetic_events' "$1" 'synthetic_events'
+}
+
+check_error 'myevent ^chr arg'			# INVALID_TYPE
+check_error 'myevent ^char str[];; int v'	# INVALID_TYPE
+check_error 'myevent char ^str]; int v'		# INVALID_NAME
+check_error 'myevent char ^str;[]'		# INVALID_NAME
+check_error 'myevent ^char str[; int v'		# INVALID_TYPE
+check_error '^mye;vent char str[]'		# BAD_NAME
+check_error 'myevent char str[]; ^int'		# INVALID_FIELD
+check_error '^myevent'				# INCOMPLETE_CMD
+
+exit 0