[llvm-bugs] [Bug 39757] New: ASTContext::getRawCommentForDeclNoCache() ignores enum value decls, returns wrong comment

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39757

            Bug ID: 39757
           Summary: ASTContext::getRawCommentForDeclNoCache() ignores enum
                    value decls, returns wrong comment
           Product: clang
           Version: 6.0
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: Frontend
          Assignee: unassignedclangbugs at nondot.org
          Reporter: djeedai at gmail.com
                CC: llvm-bugs at lists.llvm.org, neeilans at live.com,
                    richard-llvm at metafoo.co.uk

When using ASTContext::getRawCommentForDeclNoCache() to get the comment
associated with a Decl, the high-level algorithm is as follow:
- Find the location of the Decl,
- Find if a trailing comment follows the Decl, if so return it,
- Otherwise find the previous comment, located before the Decl,
- Check that no other Decl exists between that comment and the target Decl.

The last step is implemented with a fast but brittle string compare:
  // There should be no other declarations or preprocessor directives between
  // comment and declaration.
  if (Text.find_first_of(";{}#@") != StringRef::npos)
    return nullptr;

Unfortunately, for enum value decls, the separator is a comma ',' which means
that all the value decls following a comment will return that same comment:

enum class MyEnum
{
    /// Comment1
    One = 1,
    Two = 2, /// Comment2
    Three = 3,
    Four = 4,
    Five = 5,
};

Here the enum value decl "One" gets "Comment1" as expected, but for all other 4
decls getRawCommentForDeclNoCache() returns "Comment2", even though I would
expect only the second value has a comment.

A possible fix is to add the comma ',' to the list of tested characters, though
I am not sure if that can break something else. Any opinion?

Thanks

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20181122/4ab52e55/attachment.html>