FIX: Optimization of CHANGE/INSERT/APPEND integer! or char!

fixes: Oldes/Rebol-issues#1606

Author: Oldes

src/core/f-modify.c

@@ -131,13 +131,15 @@
 			// use as it is
 		}
 		else if (IS_INTEGER(src_val)) {
-			src_ser = Append_Byte(0, Int8u(src_val)); // creates a binary
+			src_ser = BUF_FORM;
+			SERIES_DATA(src_ser)[0] = Int8u(src_val);
+			SERIES_TAIL(src_ser) = 1;
 		}
 		else if (IS_BLOCK(src_val)) {
 			src_ser = Join_Binary(src_val); // NOTE: it's the shared FORM buffer!
 		}
 		else if (IS_CHAR(src_val)) {
-			src_ser = Make_Binary(6); // (I hate unicode)
+			src_ser = BUF_FORM;
 			src_ser->tail = Encode_UTF8_Char(BIN_HEAD(src_ser), VAL_CHAR(src_val));
 		}
 		else if (ANY_STR(src_val)) {
@@ -155,7 +157,9 @@
 		else Trap_Arg(src_val);
 	}
 	else if (IS_CHAR(src_val)) {
-		src_ser = Append_Byte(0, VAL_CHAR(src_val)); // unicode ok too
+		src_ser = BUF_FORM;
+		RESET_TAIL(src_ser);
+		src_ser = Append_Byte(src_ser, VAL_CHAR(src_val)); // unicode ok too
 	}
 	else if (IS_BLOCK(src_val)) {
 		src_ser = Form_Tight_Block(src_val);

src/tests/units/evaluation-test.r3

@@ -479,6 +479,28 @@ Rebol [
 		--assert 0 = p/made-blocks
 		--assert 0 = p/made-objects
 
+	;@@ https://github.com/Oldes/Rebol-issues/issues/1606
+	--test-- "dp [change binary! integer!]"
+		b: #{000000}
+		--assert 0 = select dp [change b 255] 'series-made
+		--assert b = #{FF0000}
+		--assert 0 = select dp [change/dup b 255 3] 'series-made
+		--assert b = #{FFFFFF}
+	--test-- "dp [change binary! char!]"
+		b: #{000000}
+		--assert 0 = select dp [change b #"a"] 'series-made
+		--assert b = #{610000}
+		--assert 0 = select dp [change/dup b #"a" 3] 'series-made
+		--assert b = #{616161}
+		--assert 0 = select dp [change/dup b #"á" 3] 'series-made
+		--assert b = #{C3A1C3A1C3A1}
+	--test-- "dp [change string! char!]"
+		b: "xxx"
+		--assert 0 = select dp [change b #"a"] 'series-made
+		--assert b = "axx"
+		--assert 0 = select dp [change/dup b #"a" 3] 'series-made
+		--assert b = "aaa"
+
 ===end-group===
 
 ~~~end-file~~~