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Fix a gcc -Werror=maybe-uninitialized warning in LTO mode. #3562

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@Romain-Geissler-1A
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commented Feb 12, 2019

Hi,

We have a gcc warning (error in our case since we use -Werror) when building some of our own code in LTO (link time optimisation) mode + statically linking curl which was also built with LTO mode. In practice, gcc will try at link time to optimize the whole program (so our own code + the curl code) in one go.

When doing that, with flags -Werror -Wall -Wextra, we get this warning (error):

hostip.c: In function ‘Curl_resolv’:
hostip.c:585:9: error: ‘respwait’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
hostip.c:551:9: note: ‘respwait’ was declared here

I checked the code, and this definitely looks like a false positive (gcc generates quite often false positives with -Wmaybe-uninitialized which is implied by -Wall/-Wextra). I propose to silence the false positive by actually initializing the value even if it's useless. If that does not fly for you, we might consider another fix which is adding a pragma diagnostic to actually ignore this warning, that's up to you.

Cheers,
Romain

@bagder

bagder approved these changes Feb 12, 2019

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commented Feb 12, 2019

Thanks!

@bagder bagder closed this in aa1f1d4 Feb 12, 2019

@lock lock bot locked as resolved and limited conversation to collaborators May 13, 2019

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