Format macro def with repeat

[nrc]

thread 'main' panicked at 'Box<Any>', /Users/travis/.cargo/registry/src/github.com-1ecc6299db9ec823/rustc-ap-syntax-12.0.0/parse/mod.rs:228:5
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
   1: std::sys_common::backtrace::print
   2: std::panicking::default_hook::{{closure}}
   3: std::panicking::default_hook
   4: std::panicking::rust_panic_with_hook
   5: std::panicking::begin_panic
   6: syntax::parse::filemap_to_stream
   7: syntax::parse::filemap_to_parser
   8: syntax::parse::new_parser_from_source_str
   9: rustfmt_nightly::parse_input
  10: rustfmt_nightly::format_snippet
  11: rustfmt_nightly::macros::rewrite_macro_def
  12: rustfmt_nightly::visitor::FmtVisitor::visit_item
  13: rustfmt_nightly::visitor::FmtVisitor::walk_items
  14: rustfmt_nightly::visitor::FmtVisitor::walk_mod_items
  15: rustfmt_nightly::visitor::FmtVisitor::format_separate_mod
  16: rustfmt_nightly::run
  17: rustfmt::execute
  18: rustfmt::main
  19: std::rt::lang_start::{{closure}}
  20: std::panicking::try::do_call
  21: __rust_maybe_catch_panic
  22: std::rt::lang_start_internal
  23: main

Just running cargo fmt at the root of nrc/graphql. Also happens at nrc/graphql/graphql. I have no idea why.

[topecongiro]

A minimal example:

macro lex_err($kind: ident $(, $body: expr)*) {
    Err(QlError::LexError(LexError::$kind($($body,)*)))
}

from macro def in nrc/graphql/src/parser/lexer.rs.

[topecongiro]

The minimal example:

macro foo() {
    $(x)*
}

[topecongiro]

This is due to replace_names() in macros.rs:

https://github.com/rust-lang-nursery/rustfmt/blob/8e6ee4a7625d1c6ccc2021e17c8589718a1f3474/src/macros.rs#L412-L414

We ignore an opening parenthesis after $.

Removing if c.is_alphanumeric() fixes this.

[topecongiro]

Or, rather than removing c.is_alphanumeric(), we should probably allow '(' and ')' to be included in variable name?