Bug #9669: Inconsistent SyntaxError in Ruby 2.1 mandatory keyword arguments definition without parentheses.

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.1.1
• Backport: 2.0.0: DONTNEED, 2.1: DONE

[tejanium (Teja Sophista)]

Ruby allowed us to define method with arguments without parentheses.

def foo a:, b:
  'bar'
end
#=> :foo

def foo a:, b:
  puts 'bar'
end
#=> syntax error

[sawa (Tsuyoshi Sawada)]

That is consistent. In the first example, 'bar' is interpreted as the default value of b. In the second example, the expression puts 'bar' is inappropriate as the default value, hence the error.

[phluid61 (Matthew Kerwin)]

It's because of line continuations. It interpreted the code as:

def foo a:, b: 'bar'
  # returns `nil`
end

def foo a:, b: puts 'bar'  #<< syntax error
end

There are two ways to add parentheses to make it legal:

## CODE           |  ## INTERPRETED AS
                  |
def foo a:, b:    |  def foo a:, b: puts('bar')
  puts('bar')     |    # returns `nil`
end               |  end
                  |
def baz(a:, b:)   |  def foo(a:, b:)
  puts 'bar'      |    puts 'bar'
end               |  end

I think Ruby should drop the line continuation, and interpret all three code samples like the second case above, even though it might be hard to solve with the current parser.

[nobu (Nobuyoshi Nakada)]

Or put a semicolon after b:.

Matthew Kerwin wrote:

I think Ruby should drop the line continuation, and interpret all three code samples like the second case above, even though it might be hard to solve with the current parser.

Do you mean all line continuations?

[phluid61 (Matthew Kerwin)]

Nobuyoshi Nakada wrote:

Do you mean all line continuations?

I don't think so; the only one that ever comes up as a gotcha is a final required keyword argument in a function definition.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

Applied in changeset r45405.

---

parse.y: required kwarg without parentheses

• parse.y (lex_state_e, parser_params, f_arglist, parser_yylex):
  separate EXPR_LABELARG from EXPR_BEG and let newline significant,
  so that required keyword argument can place at the end of
  argument list without parentheses. [ruby-core:61658] [Bug #9669]

[nobu (Nobuyoshi Nakada)]

• Backport changed from 2.0.0: UNKNOWN, 2.1: UNKNOWN to 2.0.0: DONTNEED, 2.1: REQUIRED

[nobu (Nobuyoshi Nakada)]

• Status changed from Closed to Open

It doesn't work yet...

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset r45408.

---

parse.y: required kwarg without parentheses

• parse.y (parser_yylex): only a newline after label should be
  significant. [ruby-core:61658] [Bug #9669]

[nobu (Nobuyoshi Nakada)]

• Has duplicate Bug #9722: Failure with multiple keyword arguments added

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.0.0: DONTNEED, 2.1: REQUIRED to 2.0.0: DONTNEED, 2.1: DONE

r45405 and r45408 were backported into ruby_2_1 branch at r46005.

[nobu (Nobuyoshi Nakada)]

• Related to Bug #10279: Syntax error on Hash with symbol syntax and nested expression: 2.1.3 regression added