hard to read the implied double negative
fix for parsing x() as identifier pattern
needs_comma was always true
rename parse_class_item to parse_struct_decl_field

two problems with the old name: they're not called classes any more, and
the word "item" has a specific connotation in the parser
rename parse_single_class_item as well
remove obsolete semicolon from list of suggestions
rename parse_instance_var to parse_name_and_ty

the name no longer made sense. perhaps this could just be inlined.
remove 3-line used-once function
s/parse_purity/parse_unsafety
removed unneeded argument to parse_record
s/one_tuple/trailing_comma (more accurate name)
parser comments
removed old type dispatch test
deleted two tests intended to test RUST_CC_ZEAL, an apparently defunct flag for the cycle collector
remove (non-parsing) test related to impl d for d feature
this issue is a dup of another one that has a correct test case

this test case has rotted wrt modern syntax. fortunately, this issue
was a dup of another one, and that one still ICEs.
This test case is obsolete for two reasons

First, it refers to a feature (trait bounds on type parameters) that's
apparently no longer in the language. Second, if I understand the issue
correctly, it should never have been a "run-pass" test because it was
supposed to fail.
changed to impl trait for type stx
Got test cases to pass, after some major surgery
this test still doesn't pass, but at least it parses...