From: Masahiro Yamada <yamada.masahiro@socionext.com>
Date: Mon, 28 May 2018 09:21:55 +0000 (+0900)
Subject: kconfig: error out if a recursive variable references itself
X-Git-Url: https://jxself.org/git/?p=carl9170fw.git;a=commitdiff_plain;h=5fc8a231376143a6132f10e8bb24950df57f9e98;hp=5fc8a231376143a6132f10e8bb24950df57f9e98

kconfig: error out if a recursive variable references itself

When using a recursively expanded variable, it is a common mistake
to make circular reference.

For example, Make terminates the following code:

  X = $(X)
  Y := $(X)

Let's detect the circular expansion in Kconfig, too.

On the other hand, a function that recurses itself is a commonly-used
programming technique.  So, Make does not check recursion in the
reference with 'call'.  For example, the following code continues
running eternally:

  X = $(call X)
  Y := $(X)

Kconfig allows circular expansion if one or more arguments are given,
but terminates when the same function is recursively invoked 1000 times,
assuming it is a programming mistake.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
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