merge revision(s) 110f242ef9b495037f59e4972ee102a8b8b372d5: [Backport #17861]

	Also `\U` after control/meta is invalid [Bug #17861]

	As well as `\u`, `\U` should be invalid there too.
	And highlight including `u`/`U` not only the backslash before it.
	---
	 parse.y                 | 12 ++++++++++--
	 test/ruby/test_parse.rb | 15 +++++++++++++++
	 2 files changed, 25 insertions(+), 2 deletions(-)

1 files changed, 10 insertions, 2 deletions

diff --git a/parse.y b/parse.y
index ca55b96ecd..b111202e8d 100644
--- a/parse.y
+++ b/parse.y
@@ -6763,7 +6763,11 @@ read_escape(struct parser_params *p, int flags, rb_encoding **encp)
 	    goto eof;
 	}
 	if ((c = nextc(p)) == '\\') {
-	    if (peek(p, 'u')) goto eof;
+	    switch (peekc(p)) {
+	      case 'u': case 'U':
+		nextc(p);
+		goto eof;
+	    }
 	    return read_escape(p, flags|ESCAPE_META, encp) | 0x80;
 	}
 	else if (c == -1 || !ISASCII(c)) goto eof;
@@ -6788,7 +6792,11 @@ read_escape(struct parser_params *p, int flags, rb_encoding **encp)
       case 'c':
 	if (flags & ESCAPE_CONTROL) goto eof;
 	if ((c = nextc(p))== '\\') {
-	    if (peek(p, 'u')) goto eof;
+	    switch (peekc(p)) {
+	      case 'u': case 'U':
+		nextc(p);
+		goto eof;
+	    }
 	    c = read_escape(p, flags|ESCAPE_CONTROL, encp);
 	}
 	else if (c == '?')