Decoder: fail on unescaped \r not followed by \n (#681)

Fixes #674

scanner.go

@@ -242,6 +242,14 @@ func scanMultilineBasicString(b []byte) ([]byte, bool, []byte, error) {
 			}
 			escaped = true
 			i++ // skip the next character
+		case '\r':
+			if len(b) < i+2 {
+				return nil, escaped, nil, newDecodeError(b[len(b):], `need a \n after \r`)
+			}
+			if b[i+1] != '\n' {
+				return nil, escaped, nil, newDecodeError(b[i:i+2], `need a \n after \r`)
+			}
+			i++ // skip the \n
 		}
 	}
 

unmarshaler_test.go

@@ -2590,6 +2590,14 @@ world'`,
 			desc: `carriage return inside basic string`,
 			data: "A = \"\r\"",
 		},
+		{
+			desc: `carriage return inside basic multiline string`,
+			data: "a=\"\"\"\r\"\"\"",
+		},
+		{
+			desc: `carriage return at the trail of basic multiline string`,
+			data: "a=\"\"\"\r",
+		},
 		{
 			desc: `carriage return inside literal string`,
 			data: "A = '\r'",