using IS_ENABLED(CONFIG_xyz) effectively

From: Vineet Gupta
Date: Mon Nov 16 2015 - 03:01:37 EST


I've been using IS_ENABLED for some time and once in a while run into an issue
which prevents seamless use. Hence posing this question to experts in the area.

C macro processor evaluates the ensuing control block even if IS_ENABLED evaluates
to false. This requires dummy #defines or worse still removing usage of IS_ENABLED

e.g. In example below even for ARCOMPACT builds, we need the ARCV2 specific define

void arch_cpu_idle(void)
if (is_isa_arcompact()) { <---- IS_ENABLED(CONFIG_ISA_ARCOMPACT)
__asm__("sleep 0x3");
} else {
const int arg = 0x10 | ARCV2_IRQ_DEF_PRIO;
__asm__("sleep 0x10");

One could argue that the interface needs to be cleanly defined to not have such
specific #defines in common code in first place. However sometime that becomes
just too tedious.

Is there a way to get around by this ?

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