wiring.h round macro causes error with avr-libc-1.7.1 fix

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I am debugging routines in the Linux avr-gcc compiler. 

I found and corrected a bug in the avr-libc-1.7.1 delay.h file, but the 
solution caused a problem with the round() function in math.h. Here is the 
report to Savannah on the delay.h bug.
https://savannah.nongnu.org/bugs/?34047

Here is a section of a post to the Arduino forum, so I don't have to retype it. 
Bug #2 is the bug affecting the Arduino library. Past versions of avr-libc may 
need that round macro, but not 1.7.1. It generates an error with that version.

Bug #1
avrlibc-1.7.1/include/util/delay.h.in

At line 44, add this:
Code:

#include <math.h>

This is required due to the calls to fabs() and ceil() in the delay.h file.

If you are using a precompiled version from a repository or download from 
Atmel, you can "retro" this fix by adding the same line to your current delay.h 
file.
/usr/../avr/include/util/delay.h
My repository installed it in "/usr/avr/include/util/delay.h", but that could 
vary by version of Linux and the repository. Some may be "/usr/local/".

Bug #2
arduino-0022/hardware/arduino/cores/arduino/wiring.h
Remark out line 79 (round macro). This causes a problem with the avr-gcc math.h 
library when you add the include to delay.h.
Code:

// #define round(x)     ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))

Original issue reported on code.google.com by t...@prolectron.com on 28 Aug 2011 at 5:03

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I'm confused.  Does Arduino include a version of avr-libc with this problem?  
If so, what's the best way to fix it?

Original comment by dmel...@gmail.com on 28 Aug 2011 at 6:16

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Don't be confused. The bug fix in the avr-libc 1.7.1 threw an error when I 
added the math.h include to the delay.h file. The "#define round ..." statement 
in the wiring.h file caused the avr-libc math.h file to generate an error. The 
define replaced the "round" in the math.h file with the macro. Oops!

The challenge was a major redo of the delay.h file from avr-libc 1.7.0 to 
1.7.1. The delay timing was off, so the new redo included a call to fabs() and 
a call to ceil(). Both are functions declared in math.h. But the include was 
not added to the finished product.

If you know a better way to resolve that issue, I am always open to suggestion.

Original comment by t...@prolectron.com on 28 Aug 2011 at 8:22

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So you're saying I need to comment out the Arduino version of round() to avoid 
breaking math.h in avr-libc 1.7.1?  Is that the version we're using now?  

Either way, is the new built-in round() a suitable replacement for the previous 
Arduino-specific one?

Original comment by dmel...@gmail.com on 31 Aug 2011 at 7:25

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Yes, the version of round in the math.h file does fine with the new version. 
But that may not be the case with previous versions of the run time library.

I think Arduino is using avr-libc 1.6.7 or the like with the Windows version. I 
have upgraded to the latest releases of all I could find. I am using avr-libc 
1.7.1. That is apparently what is included with the Atmel 8-bit toolkit 3.2.3 
on their site. It comes with avr-gcc v4.5.1. That is what I am running. I think 
I am still the only one running any of these versions. When I downloaded it 
from the Atmel site, it would not even compile the "blink" example.

I do not want to break any previous avr-libc versions by remarking out that 
macro without checking the version. The round macro may be needed in those 
older versions. Is there a define that allows you to determine the avr-libc 
version in wiring.h?

The version included in my repository was buggy, so I was trying to get a 
current version running. And now I have one.

Original comment by t...@prolectron.com on 31 Aug 2011 at 7:56

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[deleted comment]

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I found the correct define to check the version. Instead of remarking out the 
round macro, use this:

#if __AVR_LIBC_VERSION__ < 10701UL
#define round(x)     ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))
#endif

It works with version 1.7.1. You might want to check this with earlier versions.

Original comment by t...@prolectron.com on 1 Sep 2011 at 11:15

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Linux distributions just upgraded their gcc-avr to 1.7.1 too. 
Debian/Ubuntu/Mint's version of arduino has this patch:
http://patch-tracker.debian.org/patch/series/view/arduino/0022+dfsg-4/libc_1.7.1
.patch

Bug-Debian: http://bugs.debian.org/633659
--- arduino-0022+dfsg.orig/hardware/arduino/cores/arduino/wiring.h
+++ arduino-0022+dfsg/hardware/arduino/cores/arduino/wiring.h
@@ -76,7 +76,7 @@ extern "C"{
 #define max(a,b) ((a)>(b)?(a):(b))
 #define abs(x) ((x)>0?(x):-(x))
 #define constrain(amt,low,high) ((amt)<(low)?(low):((amt)>(high)?(high):(amt)))
-#define round(x)     ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))
+//#define round(x)     ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))
 #define radians(deg) ((deg)*DEG_TO_RAD)
 #define degrees(rad) ((rad)*RAD_TO_DEG)
 #define sq(x) ((x)*(x))

Original comment by showard...@gmail.com on 16 Oct 2011 at 10:27

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I think the __AVR_LIBC_VERSION__ ifdef is the superior solution.

Original comment by craigle...@gmail.com on 17 Mar 2012 at 6:14

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Still not fixed in whatever version of arduino is in Ubuntu 12.04. It's such an 
easy fix too!

Original comment by tdh...@gmail.com on 22 Jul 2012 at 4:35

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No wait, it actually is fixed, as far as I can tell. I was using an old version 
of the code.

Original comment by tdh...@gmail.com on 22 Jul 2012 at 4:48