Fix build error when using gz:: with ign-common4

[scpeters]

🦟 Bug fix

Fixes a build error

Summary

This doesn't yet fix the build error; it just illustrates it with some example code that fails to compile.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
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[mjcarroll]

The issue here is that all of the headers in the gz folder still have the ignition namespace, when they should actually be in the gz namespace. I will PR to address this. It may have been an oversite, or the result of a bad merge?

[scpeters]

I think the gz/common/config.hh.in is missing something:

• https://github.com/gazebosim/gz-math/blob/ign-math6/include/gz/math/config.hh.in#L19-L26
• https://github.com/gazebosim/gz-common/blob/ign-common4/include/gz/common/config.hh.in

[mjcarroll]

I think the gz/common/config.hh.in is missing something:

Added in 6f5c2ed

[codecov]

Codecov Report

Merging #489 (af89f97) into ign-common4 (1db040a) will not change coverage.
The diff coverage is n/a.

❗ Current head af89f97 differs from pull request most recent head e329909. Consider uploading reports for the commit e329909 to get more accurate results

@@             Coverage Diff              @@
##           ign-common4     #489   +/-   ##
============================================
  Coverage        82.86%   82.86%           
============================================
  Files               75       75           
  Lines             9558     9558           
============================================
  Hits              7920     7920           
  Misses            1638     1638           

Impacted Files	Coverage Δ
graphics/include/gz/common/HeightmapData.hh	100.00% <ø> (ø)
graphics/include/gz/common/Image.hh	97.05% <ø> (ø)
graphics/include/gz/common/ImageHeightmap.hh	88.88% <ø> (ø)
graphics/include/gz/common/MeshLoader.hh	100.00% <ø> (ø)
graphics/include/gz/common/NodeTransform.hh	100.00% <ø> (ø)
graphics/include/gz/common/SVGLoader.hh	100.00% <ø> (ø)
include/gz/common/EnumIface.hh	100.00% <ø> (ø)
include/gz/common/Filesystem.hh	100.00% <ø> (ø)
include/gz/common/FlagSet.hh	95.40% <ø> (ø)
include/gz/common/MovingWindowFilter.hh	100.00% <ø> (ø)
... and 6 more

[scpeters]

I think the gz/common/config.hh.in is missing something:

Added in 6f5c2ed

thanks!

[azeey]

LGTM! My only question is: do we need to do the same for the headers in the components of gz-common?

[mjcarroll]

do we need to do the same for the headers in the components of gz-common?

Likely yes, I will go ahead and do that. It may make sense to switch the tests to go ahead and use the gz namespace to guarantee that this is actually getting exercised, but I'm going to leave that to a follow-up.