- Prefix `check_both_ways` with `assert_` to show proper failure
  lines.

- Extract dedicated assertions for Encoding::UndefinedConversionError
  and Encoding::InvalidByteSequenceError.

* And simplify callers of get_actual_encoding().
* See [Feature #18949].
* See https://github.com/ruby/ruby/pull/6322#issuecomment-1242758474

Previously, newline: :lf was accepted but ignored.  Where it
should have been used was commented out code that didn't work,
but unlike all other invalid values, using newline: :lf did
not raise an error.

This adds support for newline: :lf and :lf_newline, for consistency
with newline: :cr and :cr_newline.  This is basically the same as
universal_newline, except that it only affects writing and not
reading due to RUBY_ECONV_NEWLINE_DECORATOR_WRITE_MASK.

Add tests for the File.open :newline option while here.

Fixes [Bug #12436]

  In ISO-2022-JP, the bytes use to code are the same as those for "<>".
  This adds regression tests to make sure that these bytes, when representing
  湿, are NOT　escaped with encode("ISO-2022-JP, xml: :text) or similar.
  These are additional regression tests for #12052.

When using a non-ASCII compatible source and destination encoding
and xml escaping (the :xml option to String#encode), the resulting
string was broken, as it used the correct non-ASCII compatible
encoding, but contained data that was ASCII-compatible instead of
compatible with the string's encoding.

Work around this issue by detecting the case where both the
source and destination encoding are non-ASCII compatible, and
transcoding the source string from the non-ASCII compatible
encoding to UTF-8. The xml escaping code will correctly handle
the UTF-8 source string and the return the correctly encoded
and escaped value.

Fixes [Bug #12052]

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>

The mapping table is generated from the ICU project:
  https://github.com/unicode-org/icu/blob/master/icu4c/source/data/mappings/ibm-720_P100-1997.ucm

Fixes bug 16233 : https://bugs.ruby-lang.org/issues/16233

`rb_funcallv_public` and `rb_respond_to` require an `ID`, not a
`Symbol`.  [Bug #16649]

Add encoding conversion (transcoding) from UTF-8 to CESU-8
and back. CESU-8 is an encoding similar to UTF-8, but encodes
codepoints above U+FFFF as two surrogates, these surrogates
again being encoded as if they were UTF-8 codepoints. This
preserves the same binary sorting order as in UTF-16. It is
also somewhat similar (although not exactly identical) to an
encoding used internally by Java.

This completes issue #15995.

enc/trans/cesu_8.trans: Add encoding conversion from/to CESU-8
test/ruby/test_transcode.rb: Add tests for above

FrozenError will be used instead of RuntimeError for exceptions
raised when there is an attempt to modify a frozen object. The
reason for this change is to differentiate exceptions related
to frozen objects from generic exceptions such as those generated
by Kernel#raise without an exception class.

From: Jeremy Evans <code@jeremyevans.net>
Signed-off-by: Urabe Shyouhei <shyouhei@ruby-lang.org>


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61131 b2dd03c8-39d4-4d8f-98ff-823fe69b080e