QtCS2017 Before Runtime discussion

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Make the API easy?

  • Copy on Write to avoid copies at runtime
  • Can we do it at compile time?
  • Let tools get const and references right
  • Warn about unnecessary copies
  • Clang can help here

Make changes easy

  • API changes are expensive
  • API looks outdated if not adapted to current paradigms (legacy code)
  • How can we make them easy
  • How can Clang help here

Clang Query

  • Think about it as SQL for the AST
  • Makes big changes much cheaper and secure

Immediate feedback vs overnight refactoring

  • Both are important
  • Immediate feedback reduces refactorings and reviews
  • Run refactorings overnight for expansive refactorings
  • Integration with the CI

Notes

  • need real examples
  • QtCreator supports only very basic refactoring tools
    • having tools outside of QtCreator and use these tools maybe inside
  • API changes need to be available by Clangtidy scripts (?)
  • what about templates?
    • concept
  • the tools cannot fit to all cases
  • this kind of tools can help to move to Qt 6(or other future versions)
  • renaming methods would be easier with this kind of tools
  • mental work to remember this new name is still there
  • can a tool do exchange deprecate things with the new "right" thing
    • using clang "Fixit" maybe possible
    • clang is here a tool and not the only compiler
    • these "Fixit" information should be inside the code
      • if it is not there it will lose sync to the code
      • maybe inside the code there can be a link to something?
  • how far can we get with transformation with tools?
  • Clangtidy is alreadys there
    • can have plugins
    • how can it be a part of our workflow
  • these tools are not available on all desktop plattforms
    • so this can not the only way to do these transformations
  • example: new Qt connections -> running transformation -> slightly different behavior
  • problem with #ifdef sections
  • kind of cross-compilation with clangtidy with necessary defines
    • possibility to skip some of problematic headers
  • warn about section where we can not do our work