Double square bracket attribute arguments can be arbitrarily complex,
and the attribute argument parsing logic recovers by skipping tokens.
As a fallback recovery mechanism, parse recovery stops before reading a
semicolon. This could lead to an infinite loop in the attribute list
parsing logic.
Clang currently has a bug where it allows you to write [[foo bar]] and
both attributes are silently accepted. This patch corrects the comma
parsing rules for such attributes and handles the test case fallout, as
a few tests were accidentally doing this.
The current C++ grammar allows an anonymous bit-field with an attribute,
but this is ambiguous (the attribute in that case could appertain to the
type instead of the bit-field). The current thinking in the Core Working
Group is that it's better to disallow attributes in that position at the
grammar level so that the ambiguity resolves in favor of applying to the
type.
During discussions about the behavior of the attribute, the Core Working
Group also felt it was better to disallow anonymous bit-fields from
specifying a default member initializer.
This implements both sets of related grammar changes.
Suggest moving the following erroneous attrib list (based on location)
[[]] struct X;
to
struct [[]] X;
Additionally, added a fixme for the current implementation that diagnoses misplaced attributes to consider using the newly introduced diagnostic (that I think is more user-friendly).
llvm-svn: 321449
Aaron Ballman