[flang-commits] [flang] [flang][Parser] Make CharBlock inherit from llvm::StringRef (PR #228482)

[Eugene Epshteyn via flang-commits]

https://github.com/eugeneepshteyn approved this pull request.

LGTM, thank you!

Please check that PR description still corresponds to the reality.

AI agent suggested adding the following regression test, which actually failed on previous revision of this PR:
```fortran
! RUN: %python %S/test_modfile.py %s %flang_fc1
! The order of COMMON blocks in a module file follows source order, with
! blank COMMON last. More than 16 blocks are needed: below that, std::sort
! uses insertion sort, which can hide an invalid source-position comparator.
module m
  common /q/ q1
  common /c/ c1
  common /m/ m1
  common /t/ t1
  common /a/ a1
  common // blank1
  common /x/ x1
  common /e/ e1
  common /k/ k1
  common /r/ r1
  common /b/ b1
  common /z/ z1
  common /g/ g1
  common /n/ n1
  common /h/ h1
  common /w/ w1
  common /d/ d1
  common /s/ s1
  common /f/ f1
  common /p/ p1
  common /y/ y1
end

!Expect: m.mod
!module m
!  real(4)::q1
!  real(4)::c1
!  integer(4)::m1
!  real(4)::t1
!  real(4)::a1
!  real(4)::blank1
!  real(4)::x1
!  real(4)::e1
!  integer(4)::k1
!  real(4)::r1
!  real(4)::b1
!  real(4)::z1
!  real(4)::g1
!  integer(4)::n1
!  real(4)::h1
!  real(4)::w1
!  real(4)::d1
!  real(4)::s1
!  real(4)::f1
!  real(4)::p1
!  real(4)::y1
!  common/q/q1
!  common/c/c1
!  common/m/m1
!  common/t/t1
!  common/a/a1
!  common/x/x1
!  common/e/e1
!  common/k/k1
!  common/r/r1
!  common/b/b1
!  common/z/z1
!  common/g/g1
!  common/n/n1
!  common/h/h1
!  common/w/w1
!  common/d/d1
!  common/s/s1
!  common/f/f1
!  common/p/p1
!  common/y/y1
!  common//blank1
!end
```

https://github.com/llvm/llvm-project/pull/228482