|  | # SPDX-License-Identifier: GPL-2.0 | 
|  |  | 
|  | # 'info' prints the argument to stdout. | 
|  | $(info,hello world 0) | 
|  |  | 
|  | # 'warning-if', if the first argument is y, sends the second argument to stderr, | 
|  | # and the message is prefixed with the current file name and line number. | 
|  | $(warning-if,y,hello world 1) | 
|  |  | 
|  | # 'error-if' is similar, but it terminates the parsing immediately. | 
|  | # The following is just no-op since the first argument is not y. | 
|  | $(error-if,n,this should not be printed) | 
|  |  | 
|  | # Shorthand | 
|  | warning = $(warning-if,y,$(1)) | 
|  |  | 
|  | # 'shell' executes a command, and returns its stdout. | 
|  | $(warning,$(shell,echo hello world 3)) | 
|  |  | 
|  | # Every newline in the output is replaced with a space, | 
|  | # but any trailing newlines are deleted. | 
|  | $(warning,$(shell,printf 'hello\nworld\n\n4\n\n\n')) | 
|  |  | 
|  | # 'filename' is expanded to the currently parsed file name, | 
|  | # 'lineno' to the line number. | 
|  | $(warning,filename=$(filename)) | 
|  | $(warning,lineno=$(lineno)) |