clang-tidy add const to methods and replace size() == 0 with empty

[timosachsenberg]

Description

readability-container-size-empty
readability-make-member-function-const

Checklist:

• Make sure that you are listed in the AUTHORS file
• Add relevant changes and new features to the CHANGELOG file
• I have commented my code, particularly in hard-to-understand areas
• New and existing unit tests pass locally with my changes
• Updated or added python bindings for changed or new classes. (Tick if no updates were necessary.)

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• http://cdash.openms.de/index.php?project=OpenMS and look for your PR. If you click in the column that lists the failed tests you will get detailed error messages.

Note:

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[timosachsenberg]

also get a failed compile here:
E:\jenkins\ws\openms\PR\bldtst\9447518b\source\src\openms_gui\include\OpenMS/VISUAL/APPLICATIONS/TOPPViewBase.h(247,39): error C2556: 'OpenMS::LayerData *OpenMS::TOPPViewBase::getCurrentLayer(void) const': overloaded function differs only by return type from 'const OpenMS::LayerData *OpenMS::TOPPViewBase::getCurrentLayer(void) const'

[timosachsenberg]

rebuild jenkins

[timosachsenberg]

compiles on gitpod... let's see who complains

[timosachsenberg]

ok there seem still to be some of the .empty() vs default constructor tests... will fix them

[timosachsenberg]

Tests passed now

[cbielow]

i cannot look at ... !empty() anymore :)

[timosachsenberg]

i cannot look at ... !empty() anymore :)

Better than size() > 0 though ;)

[timosachsenberg]

Thanks for taking the time to go through it. It is tiring I admit…