Include What You Use

[vkucera]

Include What You Use (no more, no less)

References:

• https://google.github.io/styleguide/cppguide.html#Include_What_You_Use
• https://rawgit.com/AliceO2Group/CodingGuidelines/master/coding_guidelines.html#Header_Files
• https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#sf10-avoid-dependencies-on-implicitly-included-names
• https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rs-contained
• https://llvm.org/docs/CodingStandards.html#include-as-little-as-possible
• https://github.com/include-what-you-use/include-what-you-use/blob/master/docs/WhyIWYU.md

Tools:

• https://clang.llvm.org/extra/clang-tidy/checks/misc/include-cleaner.html
• https://clang.llvm.org/extra/clang-tidy/checks/llvm/include-order.html
• https://clangd.llvm.org/design/include-cleaner
• https://clangd.llvm.org/guides/include-cleaner
• https://github.com/bkryza/clang-include-graph

Ideas:

• A file which does not include what it uses does not compile. This can be tested with:

  clang-tidy <file>

  (It should be enough to check for non-zero exit code to detect compilation errors.)
  However, if it compiles, it does not mean that all used headers are included directly nor that no unused headers are included.
• When the file compiles, the includes in it can be fixed automatically with:

  clang-tidy --fix -checks=-*,misc-include-cleaner <file>

  until there are no warnings left.
• Once all headers are self-contained, source files can be fixed with the same procedure.

[vkucera]

• [PWGHF] Include What You Use: Make headers self-contained #11357
  • [PWGJE] Include What You Use #11358
  • [PWGCF] Include What You Use #11359
  • [PWGHF,Trigger] Include What You Use #11360
  • [ALICE3] Include What You Use #11361

[vkucera]

• Add IWYU export statements to avoid proliferation of headers AliceO2#14354
• Export fairlogger/Logger.h to avoid disseminating it everywhere. AliceO2#14391
• IWYU: avoid spurious unused include report AliceO2#14392
• IWYU: export commonly used headers AliceO2#14393
• Export tuple to avoid IWYU adding it everywhere AliceO2#14403

[vkucera]

• [Common] Include What You Use #11547
• [PWGHF,Trigger] Include What You Use #11548
• [PWGHF] Include What You Use #11549
  • IWYU: BinningPolicy.h AliceO2#14323
  • [Tools] Include What You Use #11552
• [PWGJE] Include What You Use #11550
• [PWGLF] Include What You Use #11551
• [PWGHF,Tutorial] Include What You Use #11553
• [PWGHF,Tutorial] Include What You Use #11589

[vkucera]

• IWYU: TimeDeadMap.h AliceO2#14424
• [Common] Fix bugs, bad practice, performance, includes #11688