- Fix JSON and detailed record emitters to use const reference and pointers.
- Fix code to use C++ structured bindings and range-based loops, including reverse() range for locations.
- Eliminate `NL` define for "\n".
- Change JSON emitter to populate `instance_list` in an earlier loop over superclasses instead of a separate loop.
- Rename variables in JSON emitter to conform to LLVM naming conventions.
- Eliminate unused headers in detailed record emitter.
Based on the output of include-what-you-use. No other library seems affected by
the new forward declaration.
$ clang++ -E -Iinclude -I../llvm/include ../llvm/lib/TableGen/*.cpp -std=c++14 -fno-rtti -fno-exceptions | wc -l
before: 795231
after: 750654
Related Discourse thread: https://llvm.discourse.group/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D118374
