fix: raise an error when attempting to modify immutable arrays such a…

…s `algopy.arc4.Address`

BREAKING CHANGE: modifying an `algopy.arc4.Address` will now raise an error

examples/sizes.txt

@@ -6,7 +6,7 @@
  application/Reference                          177     167       -    |         92      83       - 
  arc4_dynamic_arrays/DynamicArray              2695    1931       -    |       1733    1138       - 
  arc4_numeric_comparisons/UIntNOrdering        1100     908       -    |        786     597       - 
- arc4_types/Arc4Address                          85      62       -    |         37      18       - 
+ arc4_types/Arc4Address                          79      18       -    |         34      11       - 
  arc4_types/Arc4Arrays                          623     376       -    |        368     182       - 
  arc4_types/Arc4BoolEval                        751      14       -    |        167       8       - 
  arc4_types/Arc4BoolType                        381      69       -    |        307      46       - 
@@ -130,4 +130,4 @@
  unssa/UnSSA                                    432     368       -    |        241     204       - 
  voting/VotingRoundApp                         1593    1483       -    |        734     649       - 
  with_reentrancy/WithReentrancy                 255     242       -    |        132     122       - 
- Total                                        69200   53576   53517    |      32843   21764   21720 
+ Total                                        69194   53532   53473    |      32840   21757   21713 

src/puya/awst/validation/immutable.py

@@ -0,0 +1,49 @@
+from puya import log
+from puya.awst import nodes as awst_nodes
+from puya.awst.awst_traverser import AWSTTraverser
+
+logger = log.get_logger(__name__)
+
+
+class ImmutableValidator(AWSTTraverser):
+    @classmethod
+    def validate(cls, module: awst_nodes.AWST) -> None:
+        validator = cls()
+        for module_statement in module:
+            module_statement.accept(validator)
+
+    def visit_assignment_expression(self, expr: awst_nodes.AssignmentExpression) -> None:
+        super().visit_assignment_expression(expr)
+        _validate_lvalue(expr.target)
+
+    def visit_assignment_statement(self, statement: awst_nodes.AssignmentStatement) -> None:
+        super().visit_assignment_statement(statement)
+        _validate_lvalue(statement.target)
+
+    def visit_array_pop(self, expr: awst_nodes.ArrayPop) -> None:
+        super().visit_array_pop(expr)
+        if expr.base.wtype.immutable:
+            logger.error(
+                "cannot modify - object is immutable",
+                location=expr.source_location,
+            )
+
+    def visit_array_extend(self, expr: awst_nodes.ArrayExtend) -> None:
+        super().visit_array_extend(expr)
+        if expr.base.wtype.immutable:
+            logger.error(
+                "cannot modify - object is immutable",
+                location=expr.source_location,
+            )
+
+
+def _validate_lvalue(lvalue: awst_nodes.Expression) -> None:
+    if isinstance(lvalue, awst_nodes.FieldExpression | awst_nodes.IndexExpression):
+        if lvalue.base.wtype.immutable:
+            logger.error(
+                "expression is not valid as an assignment target - object is immutable",
+                location=lvalue.source_location,
+            )
+    elif isinstance(lvalue, awst_nodes.TupleExpression):
+        for item in lvalue.items:
+            _validate_lvalue(item)

src/puya/awst/validation/main.py

@@ -1,6 +1,7 @@
 from puya.awst import nodes as awst_nodes
 from puya.awst.validation.arc4_copy import ARC4CopyValidator
 from puya.awst.validation.base_invoker import BaseInvokerValidator
+from puya.awst.validation.immutable import ImmutableValidator
 from puya.awst.validation.inner_transactions import (
     InnerTransactionsValidator,
     InnerTransactionUsedInALoopValidator,
@@ -20,3 +21,4 @@ def validate_awst(module: awst_nodes.AWST) -> None:
     BaseInvokerValidator.validate(module)
     StorageTypesValidator.validate(module)
     LabelsValidator.validate(module)
+    ImmutableValidator.validate(module)

src/puyapy/awst_build/eb/_base.py

@@ -7,7 +7,6 @@
     BinaryBooleanOperator,
     CompileTimeConstantExpression,
     Expression,
-    FieldExpression,
     Lvalue,
     SingleEvaluation,
     Statement,
@@ -220,13 +219,7 @@ def _validate_lvalue(typ: pytypes.PyType, resolved: Expression) -> Lvalue:
         raise CodeError(
             "expression is not valid as an assignment target", resolved.source_location
         )
-    if isinstance(resolved, FieldExpression):
-        if resolved.base.wtype.immutable:
-            raise CodeError(
-                "expression is not valid as an assignment target - object is immutable",
-                resolved.source_location,
-            )
-    elif isinstance(resolved, TupleExpression):
+    if isinstance(resolved, TupleExpression):
         assert isinstance(typ, pytypes.TupleLikeType)
         for item_typ, item in zip(typ.items, resolved.items, strict=True):
             _validate_lvalue(item_typ, item)

src/puyapy/awst_build/eb/arc4/string.py

@@ -8,9 +8,8 @@
     ARC4Decode,
     ARC4Encode,
     ArrayConcat,
-    ArrayExtend,
+    AssignmentStatement,
     Expression,
-    ExpressionStatement,
     Statement,
     StringConstant,
 )
@@ -104,13 +103,15 @@ def augmented_assignment(
         else:
             value = expect.argument_of_type_else_dummy(rhs, self.pytype).resolve()
 
-        return ExpressionStatement(
-            ArrayExtend(
-                base=self.resolve(),
-                other=value,
+        return AssignmentStatement(
+            target=self.resolve_lvalue(),
+            value=ArrayConcat(
+                left=self.resolve(),
+                right=value,
                 wtype=wtypes.arc4_string_alias,
                 source_location=location,
-            )
+            ),
+            source_location=location,
         )
 
     @typing.override

test_cases/arc4_types/address.py

@@ -16,8 +16,9 @@ def approval_program(self) -> bool:
         some_address = arc4.Address(SOME_ADDRESS)
         assert some_address == SOME_ADDRESS
 
-        some_address[0] = arc4.Byte(123)
-        assert some_address != SOME_ADDRESS
+        address_copy = some_address
+
+        assert some_address == address_copy
         return True
 
     def clear_state_program(self) -> bool:

test_cases/arc4_types/out/Arc4AddressContract.approval.mir

@@ -1,38 +1,26 @@
-// Op                                                                 Stack (out)
+// Op                                      Stack (out)
 // test_cases.arc4_types.address.Arc4AddressContract.approval_program() -> uint64:
 main_block@0:
     // arc4_types/address.py:8
     // address = arc4.Address(Txn.sender)
-    txn Sender                                                        address#0
+    txn Sender                             address#0
     // arc4_types/address.py:9
     // assert address == Txn.sender
-    txn Sender                                                        address#0,tmp%0#0
-    l-load-copy address#0 1                                           address#0,tmp%0#0,address#0 (copy)
-    l-load tmp%0#0 1                                                  address#0,address#0 (copy),tmp%0#0
-    ==                                                                address#0,tmp%1#0
-    assert                                                            address#0
+    txn Sender                             address#0,tmp%0#0
+    l-load-copy address#0 1                address#0,tmp%0#0,address#0 (copy)
+    l-load tmp%0#0 1                       address#0,address#0 (copy),tmp%0#0
+    ==                                     address#0,tmp%1#0
+    assert                                 address#0
     // arc4_types/address.py:11
     // assert address.native == Txn.sender
-    txn Sender                                                        address#0,tmp%3#0
-    l-load address#0 1                                                tmp%3#0,address#0
-    l-load tmp%3#0 1                                                  address#0,tmp%3#0
-    ==                                                                tmp%4#0
+    txn Sender                             address#0,tmp%3#0
+    l-load address#0 1                     tmp%3#0,address#0
+    l-load tmp%3#0 1                       address#0,tmp%3#0
+    ==                                     tmp%4#0
     assert
-    // arc4_types/address.py:16
-    // some_address = arc4.Address(SOME_ADDRESS)
-    addr "VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA" Address(VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
-    // arc4_types/address.py:19
-    // some_address[0] = arc4.Byte(123)
-    byte 0x7b                                                         Address(VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA),0x7b
-    replace2 0                                                        some_address#1
-    // arc4_types/address.py:20
-    // assert some_address != SOME_ADDRESS
-    addr "VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA" some_address#1,Address(VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
-    !=                                                                tmp%10#0
-    assert
-    // arc4_types/address.py:21
+    // arc4_types/address.py:22
     // return True
-    int 1                                                             1
+    int 1                                  1
     return
 
 

test_cases/arc4_types/out/Arc4AddressContract.approval.teal

@@ -1,7 +1,6 @@
 #pragma version 10
 
 test_cases.arc4_types.address.Arc4AddressContract.approval_program:
-    bytecblock base32(VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJPQ)
     // arc4_types/address.py:8
     // address = arc4.Address(Txn.sender)
     txn Sender
@@ -15,19 +14,7 @@ test_cases.arc4_types.address.Arc4AddressContract.approval_program:
     txn Sender
     ==
     assert
-    // arc4_types/address.py:16
-    // some_address = arc4.Address(SOME_ADDRESS)
-    bytec_0 // addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA
-    // arc4_types/address.py:19
-    // some_address[0] = arc4.Byte(123)
-    pushbytes 0x7b
-    replace2 0
-    // arc4_types/address.py:20
-    // assert some_address != SOME_ADDRESS
-    bytec_0 // addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA
-    !=
-    assert
-    // arc4_types/address.py:21
+    // arc4_types/address.py:22
     // return True
     pushint 1 // 1
     return

test_cases/arc4_types/out/Arc4AddressContract.clear.mir

@@ -1,7 +1,7 @@
 // Op                           Stack (out)
 // test_cases.arc4_types.address.Arc4AddressContract.clear_state_program() -> uint64:
 main_block@0:
-    // arc4_types/address.py:24
+    // arc4_types/address.py:25
     // return True
     int 1                       1
     return

test_cases/arc4_types/out/Arc4AddressContract.clear.teal

@@ -1,7 +1,7 @@
 #pragma version 10
 
 test_cases.arc4_types.address.Arc4AddressContract.clear_state_program:
-    // arc4_types/address.py:24
+    // arc4_types/address.py:25
     // return True
     pushint 1 // 1
     return

test_cases/arc4_types/out/Arc4AddressContract.destructured.ir

@@ -9,12 +9,9 @@ contract test_cases.arc4_types.address.Arc4AddressContract:
                 let tmp%3#0: bytes = (txn Sender)
                 let tmp%4#0: bool = (== address#0 tmp%3#0)
                 (assert tmp%4#0)
-                let some_address#1: bytes = ((replace2 0) addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA 0x7b)
-                let tmp%10#0: bool = (!= some_address#1 addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
-                (assert tmp%10#0)
                 return 1u
 
     program clear-state:
         subroutine test_cases.arc4_types.address.Arc4AddressContract.clear_state_program() -> bool:
-            block@0: // L23
+            block@0: // L24
                 return 1u

test_cases/arc4_types/out/Arc4AddressContract.ssa.ir

@@ -22,14 +22,12 @@ contract test_cases.arc4_types.address.Arc4AddressContract:
                 let some_address#0: bytes = addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA
                 let tmp%9#0: bool = (== some_address#0 addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
                 (assert tmp%9#0)
-                let assigned_value%0#0: bytes = 0x7b
-                let updated_target%0#0: bytes = (replace3 some_address#0 0u assigned_value%0#0)
-                let some_address#1: bytes = updated_target%0#0
-                let tmp%10#0: bool = (!= some_address#1 addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
+                let address_copy#0: bytes = some_address#0
+                let tmp%10#0: bool = (== some_address#0 address_copy#0)
                 (assert tmp%10#0)
                 return 1u
 
     program clear-state:
         subroutine test_cases.arc4_types.address.Arc4AddressContract.clear_state_program() -> bool:
-            block@0: // L23
+            block@0: // L24
                 return 1u

test_cases/arc4_types/out/Arc4AddressContract.ssa.opt_pass_1.ir

@@ -18,12 +18,11 @@ contract test_cases.arc4_types.address.Arc4AddressContract:
                 (assert tmp%8#0)
                 let tmp%9#0: bool = 1u
                 (assert tmp%9#0)
-                let some_address#1: bytes = ((replace2 0) addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA 0x7b)
-                let tmp%10#0: bool = (!= some_address#1 addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
+                let tmp%10#0: bool = 1u
                 (assert tmp%10#0)
                 return 1u
 
     program clear-state:
         subroutine test_cases.arc4_types.address.Arc4AddressContract.clear_state_program() -> bool:
-            block@0: // L23
+            block@0: // L24
                 return 1u

test_cases/arc4_types/out/Arc4AddressContract.ssa.opt_pass_2.ir

@@ -11,12 +11,9 @@ contract test_cases.arc4_types.address.Arc4AddressContract:
                 (assert tmp%4#0)
                 let tmp%6#0: bool = 1u
                 (assert tmp%6#0) // Address length is 32 bytes
-                let some_address#1: bytes = ((replace2 0) addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA 0x7b)
-                let tmp%10#0: bool = (!= some_address#1 addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
-                (assert tmp%10#0)
                 return 1u
 
     program clear-state:
         subroutine test_cases.arc4_types.address.Arc4AddressContract.clear_state_program() -> bool:
-            block@0: // L23
+            block@0: // L24
                 return 1u

test_cases/arc4_types/out/Arc4AddressContract.ssa.opt_pass_3.ir

@@ -9,12 +9,9 @@ contract test_cases.arc4_types.address.Arc4AddressContract:
                 let tmp%3#0: bytes = (txn Sender)
                 let tmp%4#0: bool = (== address#0 tmp%3#0)
                 (assert tmp%4#0)
-                let some_address#1: bytes = ((replace2 0) addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA 0x7b)
-                let tmp%10#0: bool = (!= some_address#1 addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
-                (assert tmp%10#0)
                 return 1u
 
     program clear-state:
         subroutine test_cases.arc4_types.address.Arc4AddressContract.clear_state_program() -> bool:
-            block@0: // L23
+            block@0: // L24
                 return 1u

test_cases/arc4_types/out/module.awst

@@ -107,12 +107,12 @@ contract Arc4StringTypesContract
     world: arc4.dynamic_array<arc4.uint8> = arc4_encode('World!', arc4.dynamic_array<arc4.uint8>)
     assert(arc4_encode('Hello World!', arc4.dynamic_array<arc4.uint8>) == hello + space + world)
     thing: arc4.dynamic_array<arc4.uint8> = arc4_encode('hi', arc4.dynamic_array<arc4.uint8>)
-    thing.extend(thing)
+    thing: arc4.dynamic_array<arc4.uint8> = thing + thing
     assert(thing == arc4_encode('hihi', arc4.dynamic_array<arc4.uint8>))
     value: arc4.dynamic_array<arc4.uint8> = arc4_encode('a', arc4.dynamic_array<arc4.uint8>) + arc4_encode('b', arc4.dynamic_array<arc4.uint8>) + arc4_encode('cd', arc4.dynamic_array<arc4.uint8>)
-    value.extend(arc4_encode('e', arc4.dynamic_array<arc4.uint8>))
-    value.extend(arc4_encode('f', arc4.dynamic_array<arc4.uint8>))
-    value.extend(arc4_encode('g', arc4.dynamic_array<arc4.uint8>))
+    value: arc4.dynamic_array<arc4.uint8> = value + arc4_encode('e', arc4.dynamic_array<arc4.uint8>)
+    value: arc4.dynamic_array<arc4.uint8> = value + arc4_encode('f', arc4.dynamic_array<arc4.uint8>)
+    value: arc4.dynamic_array<arc4.uint8> = value + arc4_encode('g', arc4.dynamic_array<arc4.uint8>)
     assert(arc4_encode('abcdefg', arc4.dynamic_array<arc4.uint8>) == value)
     assert(arc4_decode(arc4_encode('', arc4.dynamic_array<arc4.uint8>), string) == '')
     assert(arc4_decode(arc4_encode('hello', arc4.dynamic_array<arc4.uint8>), string) == 'hello')
@@ -667,8 +667,8 @@ contract Arc4AddressContract
     assert(reinterpret_cast<bytes>(zero_address) == reinterpret_cast<bytes>(global<ZeroAddress>()))
     some_address: arc4.static_array<arc4.uint8, 32> = Address("VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA")
     assert(some_address == Address("VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA"))
-    some_address[0u]: arc4.uint8 = 123_arc4u8
-    assert(some_address != Address("VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA"))
+    address_copy: arc4.static_array<arc4.uint8, 32> = some_address
+    assert(some_address == address_copy)
     return true
   }
 

test_cases/arc4_types/out_O2/Arc4AddressContract.approval.teal

@@ -1,19 +1,12 @@
 #pragma version 10
 
 test_cases.arc4_types.address.Arc4AddressContract.approval_program:
-    bytecblock base32(VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJPQ)
     txn Sender
     dupn 2
     ==
     assert
     txn Sender
     ==
     assert
-    bytec_0 // addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA
-    pushbytes 0x7b
-    replace2 0
-    bytec_0 // addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA
-    !=
-    assert
     pushint 1 // 1
     return

test_cases/arc4_types/out_O2/Arc4AddressContract.destructured.ir

@@ -9,12 +9,9 @@ contract test_cases.arc4_types.address.Arc4AddressContract:
                 let tmp%3#0: bytes = (txn Sender)
                 let tmp%4#0: bool = (== address#0 tmp%3#0)
                 (assert tmp%4#0)
-                let some_address#1: bytes = ((replace2 0) addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA 0x7b)
-                let tmp%10#0: bool = (!= some_address#1 addr VCMJKWOY5P5P7SKMZFFOCEROPJCZOTIJMNIYNUCKH7LRO45JMJP6UYBIJA)
-                (assert tmp%10#0)
                 return 1u
 
     program clear-state:
         subroutine test_cases.arc4_types.address.Arc4AddressContract.clear_state_program() -> bool:
-            block@0: // L23
+            block@0: // L24
                 return 1u