merge revision(s) cfd162d535c7a4f8b1f95255cc6be696a8b75557: [Backport #17467]

	Make String#{strip,lstrip}{,!} strip leading NUL bytes

	The documentation already specifies that they strip whitespace
	and defines whitespace to include null.

	This wraps the new behavior in the appropriate guards in the specs,
	but does not specify behavior for previous versions, because this
	is a bug that could be backported.

	Fixes [Bug #17467]
	---
	 spec/ruby/core/string/lstrip_spec.rb | 18 ++++++++++++------
	 spec/ruby/core/string/strip_spec.rb  | 22 ++++++++++------------
	 string.c                             |  4 ++--
	 test/ruby/test_string.rb             | 16 ++++++++++++++++
	 4 files changed, 40 insertions(+), 20 deletions(-)

1 files changed, 16 insertions, 0 deletions

diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index 4814872789..29ad98beaf 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -1852,6 +1852,7 @@ CODE
   def test_strip
     assert_equal(S("x"), S("      x        ").strip)
     assert_equal(S("x"), S(" \n\r\t     x  \t\r\n\n      ").strip)
+    assert_equal(S("x"), S("\x00x\x00").strip)
 
     assert_equal("0b0 ".force_encoding("UTF-16BE"),
                  "\x00 0b0 ".force_encoding("UTF-16BE").strip)
@@ -1870,6 +1871,10 @@ CODE
     assert_equal(S("x"), a.strip!)
     assert_equal(S("x"), a)
 
+    a = S("\x00x\x00")
+    assert_equal(S("x"), a.strip!)
+    assert_equal(S("x"), a)
+
     a = S("x")
     assert_nil(a.strip!)
     assert_equal(S("x") ,a)
@@ -2703,6 +2708,7 @@ CODE
   def test_rstrip
     assert_equal("  hello", "  hello  ".rstrip)
     assert_equal("\u3042", "\u3042   ".rstrip)
+    assert_equal("\u3042", "\u3042\u0000".rstrip)
     assert_raise(Encoding::CompatibilityError) { "\u3042".encode("ISO-2022-JP").rstrip }
   end
 
@@ -2723,12 +2729,17 @@ CODE
     assert_equal(nil, s4.rstrip!)
     assert_equal("\u3042", s4)
 
+    s5 = S("\u3042\u0000")
+    assert_equal("\u3042", s5.rstrip!)
+    assert_equal("\u3042", s5)
+
     assert_raise(Encoding::CompatibilityError) { "\u3042".encode("ISO-2022-JP").rstrip! }
   end
 
   def test_lstrip
     assert_equal("hello  ", "  hello  ".lstrip)
     assert_equal("\u3042", "   \u3042".lstrip)
+    assert_equal("hello  ", "\x00hello  ".lstrip)
   end
 
   def test_lstrip_bang
@@ -2747,6 +2758,11 @@ CODE
     s4 = S("\u3042")
     assert_equal(nil, s4.lstrip!)
     assert_equal("\u3042", s4)
+
+    s5 = S("\u0000\u3042")
+    assert_equal("\u3042", s5.lstrip!)
+    assert_equal("\u3042", s5)
+
   end
 
   def test_delete_prefix