[Chapel Merge] Remove remnants of the 'atomic' statement

Branch: refs/heads/main
Revision: 7869299
Author: bradcray
Link: Remove remnants of the 'atomic' statement by bradcray · Pull Request #18951 · chapel-lang/chapel · GitHub
Log Message:

Merge pull request #18951 from bradcray/remove-atomic-statement

Remove remnants of the 'atomic' statement

[reviewed by @vasslitvinov]

While working on PR #18869, I stumbled across the fact that atomic statements
are still recognized in our parser (although they then generate a warning that they're
not implemented), which was a reminder that they're still described in the language
spec as well. I don't think that atomic statements are anywhere near something we're
likely to work on in the near-term, and think that these mentions of them suggest more
of an intention than we have. For that reason, I'm proposing to remove them in this PR.

For posterity, the closest we got to implementing these was an effort by Srinivas
Sriharan circa 2011, which was archived here:
GitHub - chapel-lang/chapel-attic at collaborations/gtm
My recollection was that this implementation was correct for the time, but failed to
get merged into the main branch due to a combination of not having portable atomics
combined with it not being on a graduating PhD student's critical path (and potentially
a lack of resources internally to carry the work forward).

Resolves #9939.

Modified Files:
R test/parallel/atomic/bradc/atomicSingleStmt.chpl

R test/parallel/atomic/bradc/atomicSingleStmt.good
M compiler/AST/build.cpp
M compiler/include/bison-chapel.h
M compiler/include/build.h
M compiler/include/flex-chapel.h
M compiler/parser/bison-chapel.cpp
M compiler/parser/chapel.ypp
M compiler/parser/flex-chapel.cpp
M doc/rst/language/spec/memory-consistency-model.rst
M doc/rst/language/spec/organization.rst
M doc/rst/language/spec/statements.rst
M doc/rst/language/spec/task-parallelism-and-synchronization.rst
M test/multilocale/deitz/needMultiLocales/raCommCheck.chpl
M test/multilocale/deitz/needMultiLocales/raCommCheck.compopts
M test/studies/hpcc/RA/bradc/parallel/ra-dist.chpl
M test/studies/hpcc/RA/bradc/parallel/ra-dist.compopts
M test/studies/hpcc/RA/diten/ra.chpl
M test/studies/hpcc/RA/diten/ra.good
M test/studies/hpcc/RA/marybeth/ra3.chpl
M test/studies/hpcc/RA/marybeth/ra3.good

Compare: https://github.com/chapel-lang/chapel/compare/74bdaa8e61a7...786929989fee