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Project Explorer #undef warning [message #1764917]

Sat, 03 June 2017 14:57

dh 29

Messages: 3
Registered: June 2017

Junior Member

I am using Eclipse Mars.2 Release (4.5.2) under WIn10.

This is my 1st attempt of cross compiling on a Win machine for an ARM / Linux target (happens to be an iMX7). I am using a Linaro tool-chain.

A simple project using 'pthreads' compiles OK without any warnings.

Whats annoying me is that I have ten #undef warnings in the Project Explorer window (see attached) that I don't understand.

Can anybody explain / help?

Attachment: Eclipse Mars undef warnings.jpg
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Re: Project Explorer #undef warning [message #1765001 is a reply to message #1764917]

Mon, 05 June 2017 16:27

Jonah Graham

Messages: 416
Registered: June 2014

Senior Member

This looks like CDT is interpretting some of the #undefs as include directories. That (obviously) shouldn't happen, but it should also be innocuous.

I have tried to reproduce on my machine, with gcc-linaro-6.3.1-2017.05-i686-mingw32_arm-linux-gnueabihf.tar.xz and Neon.3 (which is the most recent release) and although I can see those #undefs in the output of the command CDT runs to find out includes and defines, I can't see how it could be getting it wrong.

I will download Mars.2 to see if it fails there.

[Updated on: Mon, 05 June 2017 16:28]

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Re: Project Explorer #undef warning [message #1765005 is a reply to message #1765001]

Mon, 05 June 2017 16:39

Jonah Graham

Messages: 416
Registered: June 2014

Senior Member

Mars.2 works ok for me too.

I am pretty sure you can just ignore it as those #undefs are not directories, so no header files will be found there.

What you can do is force the scanner (the part of CDT that runs your gcc to find out includes) to run again. Perhaps there is a race condition as the #undefs are printed on stdout and the includes on stderr when running gcc.

To re-run manually:
0) Project properties -> C/C++ General -> Preprocessor Include Paths -> Providers tab
1) Select "CDT Cross GCC Built-in Compiler Settings"
2) (optional) Check the "Allocate console in the console view"
3) Press Clear entries
4) Press OK

See the screenshot if that helps.

This will re-run the scanner, if it gives a different result you have found some kind of race condition and I would be ever so grateful if you could report back or file a bug: https://bugs.eclipse.org/bugs/enter_bug.cgi?product=CDT

If you did the optional step 2, you will now have a console that shows exactly what CDT did to get macros and include paths.

index.php/fa/29560/0/

Attachment: rerunscanner.png
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Re: Project Explorer #undef warning [message #1765006 is a reply to message #1765005]

Mon, 05 June 2017 16:43

Jonah Graham

Messages: 416
Registered: June 2014

Senior Member

More info if desired about scanner discovery: https://help.eclipse.org/neon/topic/org.eclipse.cdt.doc.user/reference/cdt_u_pref_build_scanner_discovery.htm and https://help.eclipse.org/neon/topic/org.eclipse.cdt.doc.user/concepts/cdt_c_scanner_discovery.htm

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Re: Project Explorer #undef warning [message #1765021 is a reply to message #1765006]

Mon, 05 June 2017 18:37

dh 29

Messages: 3
Registered: June 2017

Junior Member

Jonah, thanks for the suggestions and info links. Looks like I've got a lot to learn...in fact I know I've got a lot to learn!
I'll force a re-run of the CDT scanner and let you know the results.

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Re: Project Explorer #undef warning [message #1765024 is a reply to message #1765021]

Mon, 05 June 2017 19:27

dh 29

Messages: 3
Registered: June 2017

Junior Member

Jonah, I've forced a CDT re-scan as you described, but the ''#undef warnings' remained.

I've attached the console output for the CDT re-scan. Within this output there are some 'duplicate paths' listed - not sure if this is normal/expected?

Attachment: MARS_2.CDT_Rescan.txt
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Re: Project Explorer #undef warning [message #1765124 is a reply to message #1765024]

Tue, 06 June 2017 20:48

Jonah Graham

Messages: 416
Registered: June 2014

Senior Member

OK, thanks for the info. I have reproduced your environment as well as I can (Win 10, Mars.2 same version of Linaro, even same paths) and for the longest time I could not reproduce the problem. In the end I decided to re-run the scan (clear entries) dozens of times and I have just reproduced the problem. I still believe that it does not hurt anything, but is still wrong (and potentially a sign of another bug lurking). I have raised https://bugs.eclipse.org/bugs/show_bug.cgi?id=517908 to fix/track the issue. Please add yourself to the CC list to track the progress.

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