xref: /linux/scripts/kconfig/tests/preprocess/variable/Kconfig (revision 71e2f4dd5a65bd8dbca0b77661e75eea471168f8) 
1# SPDX-License-Identifier: GPL-2.0
2
3# Shorthand
4warning = $(warning-if,y,$(1))
5
6# Simply expanded variable.
7X := 1
8SIMPLE := $(X)
9X := 2
10$(warning,SIMPLE = $(SIMPLE))
11
12# Recursively expanded variable.
13X := 1
14RECURSIVE = $(X)
15X := 2
16$(warning,RECURSIVE = $(RECURSIVE))
17
18# Append something to a simply expanded variable.
19Y := 3
20SIMPLE += $(Y)
21Y := 4
22$(warning,SIMPLE = $(SIMPLE))
23
24# Append something to a recursively expanded variable.
25Y := 3
26RECURSIVE += $(Y)
27Y := 4
28$(warning,RECURSIVE = $(RECURSIVE))
29
30# Use += operator to an undefined variable.
31# This works as a recursively expanded variable.
32Y := 3
33UNDEFINED_VARIABLE += $(Y)
34Y := 4
35$(warning,UNDEFINED_VARIABLE = $(UNDEFINED_VARIABLE))
36
37# You can use variable references for the lefthand side of assignment statement.
38X := A
39Y := B
40$(X)$(Y) := 5
41$(warning,AB = $(AB))
42
43# User-defined function.
44greeting = $(1), my name is $(2).
45$(warning,$(greeting,Hello,John))
46
47# The number of arguments is not checked for user-defined functions.
48# If some arguments are optional, it is useful to pass fewer parameters.
49# $(2) will be blank in this case.
50$(warning,$(greeting,Hello))
51
52# Unreferenced parameters are just ignored.
53$(warning,$(greeting,Hello,John,ignored,ignored))
54