Add string encoding IBM720 alias CP720 (#3803)

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

1 files changed, 8 insertions, 0 deletions

diff --git a/spec/ruby/core/string/valid_encoding_spec.rb b/spec/ruby/core/string/valid_encoding_spec.rb
index 09916df079..3e820a5c6d 100644
--- a/spec/ruby/core/string/valid_encoding_spec.rb
+++ b/spec/ruby/core/string/valid_encoding_spec.rb
@@ -100,6 +100,14 @@ describe "String#valid_encoding?" do
     str.force_encoding('UTF8-MAC').valid_encoding?.should be_true
   end
 
+  ruby_version_is '3.0' do
+    it "returns true for IBM720 encoding self is valid in" do
+      str = "\u{6754}"
+      str.force_encoding('IBM720').valid_encoding?.should be_true
+      str.force_encoding('CP720').valid_encoding?.should be_true
+    end
+  end
+
   it "returns false if self is valid in one encoding, but invalid in the one it's tagged with" do
     str = "\u{8765}"
     str.valid_encoding?.should be_true