FIX: insert/append/change binary! string!

fixes: Oldes/Rebol-issues#1791

Author: Oldes

src/core/f-modify.c

@@ -125,9 +125,12 @@
 	if (dups < 0) return (action == A_APPEND) ? 0 : dst_idx;
 	if (action == A_APPEND || dst_idx > tail) dst_idx = tail;
 
-	// If the src_val is not a string, then we need to create a string:
+	// If the src_val is not same type like trg_val, we must convert it
 	if (GET_FLAG(flags, AN_SERIES)) { // used to indicate a BINARY series
-		if (IS_INTEGER(src_val)) {
+		if (IS_BINARY(src_val)) {
+			// use as it is
+		}
+		else if (IS_INTEGER(src_val)) {
 			src_ser = Append_Byte(0, Int8u(src_val)); // creates a binary
 		}
 		else if (IS_BLOCK(src_val)) {
@@ -137,7 +140,19 @@
 			src_ser = Make_Binary(6); // (I hate unicode)
 			src_ser->tail = Encode_UTF8_Char(BIN_HEAD(src_ser), VAL_CHAR(src_val));
 		}
-		else if (!ANY_BINSTR(src_val)) Trap_Arg(src_val);
+		else if (ANY_STR(src_val)) {
+			// here is used temporary src_len, used to limit conversion of the string to binary
+			// If /part is used, not complete src is converted to binary (UTF8).
+			// This src_len is modified by purpose later so the result may be shorter.
+			// Like in this case: #{E1} == append/part #{} "^(1234)" 1
+			if (action != A_CHANGE && GET_FLAG(flags, AN_PART)) {
+				src_len = dst_len;
+			} else {
+				src_len = VAL_LEN(src_val);
+			}
+			src_ser = Encode_UTF8_Value(src_val, src_len, FALSE); // NOTE: uses shared FORM buffer!
+		}
+		else Trap_Arg(src_val);
 	}
 	else if (IS_CHAR(src_val)) {
 		src_ser = Append_Byte(0, VAL_CHAR(src_val)); // unicode ok too

src/core/s-unicode.c

@@ -1189,8 +1189,7 @@ ConversionResult ConvertUTF8toUTF32 (
 
 		size = Length_As_UTF8(up, len, TRUE, (REBOOL)ccr);
 		cp = Reset_Buffer(ser, size + (GET_FLAG(opts, ENC_OPT_BOM) ? 3 : 0));
-        UNUSED(cp);
-		Encode_UTF8(Reset_Buffer(ser, size), size, up, &len, TRUE, ccr);
+		Encode_UTF8(cp, size, up, &len, TRUE, ccr);
 	}
 	else {
 		REBYTE *bp = (REBYTE*)src;

src/tests/units/series-test.r3

@@ -173,6 +173,57 @@ Rebol [
 
 ===end-group===
 
+;@@ https://github.com/Oldes/Rebol-issues/issues/1791
+===start-group=== "APPEND binary!"
+	--test-- "APPEND binary! binary!"
+		--assert #{0102}     = append #{01} #{02}
+		--assert #{0102}     = append next #{01} #{02}
+	--test-- "APPEND binary! string!"
+		--assert #{0001}     = append #{00} "^(01)"
+		--assert #{0001}     = append next #{00} "^(01)"
+		--assert #{00E28690} = append #{00} "^(2190)"
+		--assert #{00E28690} = append next #{00} "^(2190)"
+	--test-- "APPEND binary! file!"
+		--assert #{616263}   = append #{} %abc
+		--assert #{C3A162}   = append #{} %áb
+	--test-- "APPEND binary! char!"
+		--assert #{0001}     = append #{00} #"^(01)"
+		--assert #{00E28690} = append #{00} #"^(2190)"
+	--test-- "APPEND/part binary!"
+		--assert #{01} = append/part #{} #{0102} 1
+		--assert #{01} = append/part #{} "^(01)^(02)" 1
+		--assert #{E2} = append/part #{} "^(2190)" 1 ;-- by design!
+===end-group===
+
+===start-group=== "INSERT binary!"
+	--test-- "INSERT binary! binary!"
+		--assert #{0201}     = head insert #{01} #{02}
+		--assert #{0102}     = head insert next #{01} #{02}
+	--test-- "INSERT binary! string!"
+		--assert #{0100}     = head insert #{00} "^(01)"
+		--assert #{0001}     = head insert next #{00} "^(01)"
+		--assert #{E2869000} = head insert #{00} "^(2190)"
+		--assert #{00E28690} = head insert next #{00} "^(2190)"
+	--test-- "INSERT binary! file!"
+		--assert #{61626300} = head insert #{00} %abc
+		--assert #{C3A16200} = head insert #{00} %áb
+	--test-- "INSERT binary! char!"
+		--assert #{0100}     = head insert #{00} #"^(01)"
+		--assert #{E2869000} = head insert #{00} #"^(2190)"
+	--test-- "INSERT/part binary!"
+		--assert #{0100} = head insert/part #{00} #{0102} 1
+		--assert #{0100} = head insert/part #{00} "^(01)^(02)" 1
+		--assert #{E200} = head insert/part #{00} "^(2190)" 1 ;-- by design!
+===end-group===
+
+===start-group=== "CHANGE binary!"
+	--test-- "CHANGE binary! string!"
+		--assert #{E188B4} = head change #{} "^(1234)"
+		--assert #{E188B4} = head change #{00} "^(1234)"
+		--assert #{E188B4} = head change #{0000} "^(1234)"
+		--assert #{E188B403} = head change/part #{010203} "^(1234)" 2
+===end-group===
+
 ===start-group=== "TAKE"
 	--test-- "take string!"
 	s: "a"