Add packing for dynamic array and slice types (#18051)

* added tests for new abi encoding features (#4)

* added tests from bytes32[][] and string[]

* added offset to other types

* formatting

* Abi/dynamic types (#5)

* Revert "Abi/dynamic types (#5)" (#6)

This reverts commit dabca31d797623d43bd780721fc0ad461d24be53.

* Abi/dynamic types (#7)

* some cleanup

* Apply suggestions from code review

apply suggestions

Co-Authored-By: vedhavyas <vedhavyas.singareddi@gmail.com>

* added better formatting (#8)

* review chnages

* better comments

1 files changed, 7 insertions, 12 deletions

diff --git a/accounts/abi/argument.go b/accounts/abi/argument.go
index 93b513c34..f544c80db 100644
--- a/accounts/abi/argument.go
+++ b/accounts/abi/argument.go
@@ -243,11 +243,7 @@ func (arguments Arguments) Pack(args ...interface{}) ([]byte, error) {
 	// input offset is the bytes offset for packed output
 	inputOffset := 0
 	for _, abiArg := range abiArgs {
-		if abiArg.Type.T == ArrayTy {
-			inputOffset += 32 * abiArg.Type.Size
-		} else {
-			inputOffset += 32
-		}
+		inputOffset += getDynamicTypeOffset(abiArg.Type)
 	}
 	var ret []byte
 	for i, a := range args {
@@ -257,14 +253,13 @@ func (arguments Arguments) Pack(args ...interface{}) ([]byte, error) {
 		if err != nil {
 			return nil, err
 		}
-		// check for a slice type (string, bytes, slice)
-		if input.Type.requiresLengthPrefix() {
-			// calculate the offset
-			offset := inputOffset + len(variableInput)
+		// check for dynamic types
+		if isDynamicType(input.Type) {
 			// set the offset
-			ret = append(ret, packNum(reflect.ValueOf(offset))...)
-			// Append the packed output to the variable input. The variable input
-			// will be appended at the end of the input.
+			ret = append(ret, packNum(reflect.ValueOf(inputOffset))...)
+			// calculate next offset
+			inputOffset += len(packed)
+			// append to variable input
 			variableInput = append(variableInput, packed...)
 		} else {
 			// append the packed value to the input