ESP8266: "error: 'abs' cannot be used as a function"

Projects Programming
1

I have a huge-ish application that has to run on both AVR and ESP. No problem compiling for AVR, but when compiling for ESP, the below line throws "error: 'abs' cannot be used as a function".

curStepDelay = (100000UL / abs(gaugeTargetPos - gaugeCurPos)) / 1000;
                                                                                             ^

I cannot understand why.... Both gaugeTargetPos and gaugeCurPos are declared as ints. AFAICT, abs is defined as:

#define abs(x) ((x)>0?(x):-(x))

VS Intellisense shows abs expands to:

((gaugeTargetPos - gaugeCurPos)>0?(gaugeTargetPos - gaugeCurPos):-(gaugeTargetPos - gaugeCurPos))

That all looks perfectly legit to me. So why the error? Is this just a quirk/bug of this version of the ESP compiler?

This is actually not a problem for me, since this class is not needed on the ESP implementation, but I am curious why this error occurs, just in case it comes up again in the future, since I will be using the ESP a lot for a while.

Regards,
Ray L.

2

Can you reproduce the problem with a small program that you can post here ?

3

Oddly, no. A simple program containing little more than the offending line compiles just fine. That makes this smell like some bizarro build system or compiler bug, doesn't it?

Regards,
Ray L.

4

Can you post the full error message.
It seems like abs is a valid identifier but it is not a macro nor function.

5

Don't use abs, include and use std::abs.

Pieter