Merge tag 'kconfig-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kconfig updates from Masahiro Yamada:
 "Kconfig now supports new functionality to perform textual
  substitution. It has been a while since Linus suggested to move
  compiler option tests from makefiles to Kconfig. Finally, here it is.

  The implementation has been generalized into a Make-like macro
  language.

  Some built-in functions such as 'shell' are provided. Variables and
  user-defined functions are also supported so that 'cc-option',
  'ld-option', etc. are implemented as macros.

  Summary:

   - refactor package checks for building {m,n,q,g}conf

   - remove unused/unmaintained localization support

   - remove Kbuild cache

   - drop CONFIG_CROSS_COMPILE support

   - replace 'option env=' with direct variable expansion

   - add built-in functions such as 'shell'

   - support variables and user-defined functions

   - add helper macros as as 'cc-option'

   - add unit tests and a document of the new macro language

   - add 'testconfig' to help

   - fix warnings from GCC 8.1"

* tag 'kconfig-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
  kconfig: Avoid format overflow warning from GCC 8.1
  kbuild: Move last word of nconfig help to the previous line
  kconfig: Add testconfig into make help output
  kconfig: add basic helper macros to scripts/Kconfig.include
  kconfig: show compiler version text in the top comment
  kconfig: test: add Kconfig macro language tests
  Documentation: kconfig: document a new Kconfig macro language
  kconfig: error out if a recursive variable references itself
  kconfig: add 'filename' and 'lineno' built-in variables
  kconfig: add 'info', 'warning-if', and 'error-if' built-in functions
  kconfig: expand lefthand side of assignment statement
  kconfig: support append assignment operator
  kconfig: support simply expanded variable
  kconfig: support user-defined function and recursively expanded variable
  kconfig: begin PARAM state only when seeing a command keyword
  kconfig: replace $(UNAME_RELEASE) with function call
  kconfig: add 'shell' built-in function
  kconfig: add built-in function support
  kconfig: make default prompt of mainmenu less specific
  kconfig: remove sym_expand_string_value()
  ...

1 files changed, 53 insertions, 0 deletions

diff --git a/scripts/kconfig/tests/preprocess/variable/Kconfig b/scripts/kconfig/tests/preprocess/variable/Kconfig
new file mode 100644
index 000000000000..9ce2f95cbd24
--- /dev/null
+++ b/scripts/kconfig/tests/preprocess/variable/Kconfig
@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: GPL-2.0
+
+# Shorthand
+warning = $(warning-if,y,$(1))
+
+# Simply expanded variable.
+X := 1
+SIMPLE := $(X)
+X := 2
+$(warning,SIMPLE = $(SIMPLE))
+
+# Recursively expanded variable.
+X := 1
+RECURSIVE = $(X)
+X := 2
+$(warning,RECURSIVE = $(RECURSIVE))
+
+# Append something to a simply expanded variable.
+Y := 3
+SIMPLE += $(Y)
+Y := 4
+$(warning,SIMPLE = $(SIMPLE))
+
+# Append something to a recursively expanded variable.
+Y := 3
+RECURSIVE += $(Y)
+Y := 4
+$(warning,RECURSIVE = $(RECURSIVE))
+
+# Use += operator to an undefined variable.
+# This works as a recursively expanded variable.
+Y := 3
+UNDEFINED_VARIABLE += $(Y)
+Y := 4
+$(warning,UNDEFINED_VARIABLE = $(UNDEFINED_VARIABLE))
+
+# You can use variable references for the lefthand side of assignment statement.
+X := A
+Y := B
+$(X)$(Y) := 5
+$(warning,AB = $(AB))
+
+# User-defined function.
+greeting = $(1), my name is $(2).
+$(warning,$(greeting,Hello,John))
+
+# The number of arguments is not checked for user-defined functions.
+# If some arguments are optional, it is useful to pass fewer parameters.
+# $(2) will be blank in this case.
+$(warning,$(greeting,Hello))
+
+# Unreferenced parameters are just ignored.
+$(warning,$(greeting,Hello,John,ignored,ignored))