[PATCH] D55955: Properly diagnose [[nodiscard]] on the body of a range-based for loop

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman updated this revision to Diff 179475.
aaron.ballman marked 3 inline comments as done.
aaron.ballman added a comment.

Updated based on review feedback.

The lookahead wasn't too annoying to thread through, but I did run into surprises in TreeTransform where I can't use the lookahead to determine whether the expression statement should be warned on or not. The solution I have is serviceable, but perhaps there's a better approach to be taken.

The changes introduce warnings where they were previously missed, such as in init-statements. The only unfortunate behavioral side effect comes from range-based for loops that have an expression as the first statement -- in addition to the error, we now trigger an unused expression result warning, but restructuring the code to avoid it would be challenging for such an edge case (and the warning behavior seems reasonable).


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D55955/new/

https://reviews.llvm.org/D55955

Files:
  include/clang/Parse/Parser.h
  include/clang/Sema/Sema.h
  lib/Parse/ParseObjc.cpp
  lib/Parse/ParseOpenMP.cpp
  lib/Parse/ParseStmt.cpp
  lib/Sema/SemaExprCXX.cpp
  lib/Sema/SemaOpenMP.cpp
  lib/Sema/SemaStmt.cpp
  lib/Sema/TreeTransform.h
  test/CXX/stmt.stmt/stmt.select/p3.cpp
  test/CodeCompletion/pragma-macro-token-caching.c
  test/Parser/cxx1z-init-statement.cpp
  test/Parser/switch-recovery.cpp
  test/SemaCXX/cxx1z-init-statement.cpp
  test/SemaCXX/for-range-examples.cpp
  test/SemaCXX/warn-unused-result.cpp
  test/SemaObjCXX/foreach.mm

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