[clang-format] Do not break after ObjC category open paren

Summary:
Previously, `clang-format` would break Objective-C
category extensions after the opening parenthesis to avoid
breaking the protocol list:

```
% echo "@interface ccccccccccccc (ccccccccccc) <ccccccccccccc> { }" | \
  clang-format -assume-filename=foo.h -style="{BasedOnStyle: llvm, \
  ColumnLimit: 40}"
@interface ccccccccccccc (
    ccccccccccc) <ccccccccccccc> {
}
```

This looks fairly odd, as we could have kept the category extension
on the previous line.

Category extensions are a single item, so they are generally very
short compared to protocol lists. We should prefer breaking after the
opening `<` of the protocol list over breaking after the opening `(`
of the category extension.

With this diff, we now avoid breaking after the category extension's
open paren, which causes us to break after the protocol list's
open angle bracket:

```
% echo "@interface ccccccccccccc (ccccccccccc) <ccccccccccccc> { }" | \
  ./bin/clang-format -assume-filename=foo.h -style="{BasedOnStyle: llvm, \
  ColumnLimit: 40}"
@interface ccccccccccccc (ccccccccccc) <
    ccccccccccccc> {
}
```

Test Plan: New test added. Confirmed test failed before diff and
  passed after diff by running:
  % make -j16 FormatTests && ./tools/clang/unittests/Format/FormatTests

Reviewers: djasper, jolesiak

Reviewed By: djasper

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D45526

llvm-svn: 329919
2 files changed
tree: 6745e90cebebe99ce5a55ddc574afe629f111f6a
  1. clang/
  2. clang-tools-extra/
  3. compiler-rt/
  4. debuginfo-tests/
  5. libclc/
  6. libcxx/
  7. libcxxabi/
  8. libunwind/
  9. lld/
  10. lldb/
  11. llgo/
  12. llvm/
  13. openmp/
  14. parallel-libs/
  15. polly/
  16. README.md
README.md

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