refactor: let arc-4 method arg type check be done in ir layer

changelog.d/20260205_100910_bobby.lat_arg_check.md

@@ -0,0 +1,42 @@
+<!--
+A new scriv changelog fragment.
+
+Uncomment the section that is right (remove the HTML comment wrapper).
+For top level release notes, leave all the headers commented out.
+-->
+
+<!--
+### Removed
+
+- A bullet item for the Removed category.
+
+-->
+<!--
+### Added
+
+- A bullet item for the Added category.
+
+-->
+
+### Changed
+
+- Improved error message for unsupported ARC-4 method types to provide more accurate source locations.
+
+<!--
+### Deprecated
+
+- A bullet item for the Deprecated category.
+
+-->
+<!--
+### Fixed
+
+- A bullet item for the Fixed category.
+
+-->
+<!--
+### Security
+
+- A bullet item for the Security category.
+
+-->

src/puya/ir/arc4_types.py

@@ -212,7 +212,10 @@ def wtype_to_arc4(
             return wtype.name
     maybe_arc4_wtype = maybe_wtype_to_arc4_wtype(wtype)
     if maybe_arc4_wtype is None:
-        raise CodeError("unsupported type for an ARC-4 method", loc)
+        error_msg = "unsupported type for an ARC-4 method"
+        if is_return:
+            error_msg = "unsupported return type for an ARC-4 method"
+        raise CodeError(error_msg, loc)
     return get_arc4_name(maybe_arc4_wtype, use_alias=True)
 
 

src/puyapy/models.py

@@ -18,7 +18,6 @@
     ContractMethod,
     StateTotals,
 )
-from puya.errors import CodeError
 from puya.parse import SourceLocation
 from puya.program_refs import ContractReference
 from puyapy.awst_build import pytypes
@@ -51,25 +50,6 @@ class ARC4ABIMethodData:
     config: ARC4ABIMethodConfig
     is_bare: bool = attrs.field(default=False, init=False)
     _signature: dict[str, pytypes.PyType]
-    _arc4_signature: Mapping[str, pytypes.PyType] = attrs.field(init=False)
-
-    @_arc4_signature.default
-    def _arc4_signature_default(self) -> Mapping[str, pytypes.PyType]:
-        from puyapy.awst_build.arc4_utils import pytype_to_arc4_pytype  # TODO: resolve circularity
-
-        def on_error(bad_type: pytypes.PyType, loc: SourceLocation | None) -> typing.Never:
-            raise CodeError(f"invalid type for an ARC-4 method: {bad_type}", loc)
-
-        pass_resources_by_value = self.config.resource_encoding == "value"
-        return {
-            k: pytype_to_arc4_pytype(
-                v,
-                on_error=on_error,
-                encode_resource_types=pass_resources_by_value or k == "output",
-                source_location=self.source_location,
-            )
-            for k, v in self._signature.items()
-        }
 
     @property
     def signature(self) -> Mapping[str, pytypes.PyType]:
@@ -79,22 +59,12 @@ def signature(self) -> Mapping[str, pytypes.PyType]:
     def return_type(self) -> pytypes.PyType:
         return self._signature["output"]
 
-    @cached_property
-    def arc4_return_type(self) -> pytypes.PyType:
-        return self._arc4_signature["output"]
-
     @cached_property
     def argument_types(self) -> Sequence[pytypes.PyType]:
         names, types = zip(*self._signature.items(), strict=True)
         assert names[-1] == "output"
         return tuple(types[:-1])
 
-    @cached_property
-    def arc4_argument_types(self) -> Sequence[pytypes.PyType]:
-        names, types = zip(*self._arc4_signature.items(), strict=True)
-        assert names[-1] == "output"
-        return tuple(types[:-1])
-
 
 ARC4MethodData: typing.TypeAlias = ARC4BareMethodData | ARC4ABIMethodData
 

tests/test_expected_output/arc4.test

@@ -529,14 +529,7 @@ class MyContract(ARC4Contract): ## E: Non-abstract ARC-4 contract has no methods
     def b(self) -> None:
         pass
 
-    @arc4.abimethod ## E: invalid type for an ARC-4 method: algopy.BoxRef
-    def c(self, box: BoxRef) -> None:
-        pass
-
-    @arc4.abimethod ## E: invalid type for an ARC-4 method: algopy.BoxRef
-    def d(self, arg: Bytes) -> BoxRef:
-        return BoxRef(key=arg)
-
+
     @arc4.baremethod # type: ignore[arg-type] ## E: bare methods should have no arguments or return values
     def e(self, x: UInt64) -> None:
         pass
@@ -546,6 +539,19 @@ class MyContract(ARC4Contract): ## E: Non-abstract ARC-4 contract has no methods
         return UInt64(0)
 
 
+## case: bad_signatures_from_ir_layer
+from algopy import *
+
+class MyContract(ARC4Contract): 
+
+    @arc4.abimethod
+    def c(self, box: BoxRef) -> None: ## E: unsupported type for an ARC-4 method
+        pass
+
+    @arc4.abimethod ## E: unsupported return type for an ARC-4 method
+    def d(self, arg: Bytes) -> BoxRef: 
+        return BoxRef(key=arg)
+
 ## case: test_string
 from algopy import arc4, subroutine
 

tests/test_expected_output/arrays.test

@@ -109,31 +109,43 @@ class ArrayContract(arc4.ARC4Contract):
     def imm_itxn2_arg(self, arr: ImmutableArray[itxn.PaymentInnerTransaction]) -> None: ## E: arrays can only contain persistable elements
         pass
 
-    @arc4.abimethod ## E: invalid type for an ARC-4 method: algopy.ReferenceArray[algopy.gtxn.Transaction]
-    def arr_txn_arg(self, arr: ReferenceArray[gtxn.Transaction]) -> None:
+    @arc4.abimethod()
+    def test_reference_array_extend_with_arc4_bool(self) -> None:
+        arr = ReferenceArray[arc4.Bool]()
+        dyn_arr = arc4.DynamicArray[arc4.Bool]()
+        arr.extend(dyn_arr) ## E: extending a reference array with an ARC-4 encoded bool type is not supported
+
+## case: test_array_element_error_from_ir_layer
+import typing
+from algopy import *
+
+
+class ArrayContract(arc4.ARC4Contract):
+
+    @arc4.abimethod
+    def arr_txn_arg(self, arr: ReferenceArray[gtxn.Transaction]) -> None: ## E: unsupported type for an ARC-4 method
         pass
 
-    @arc4.abimethod ## E: invalid type for an ARC-4 method: algopy.ReferenceArray[algopy.itxn.Payment]
-    def arr_itxn_arg(self, arr: ReferenceArray[itxn.Payment]) -> None:
+    @arc4.abimethod
+    def arr_itxn_arg(self, arr: ReferenceArray[itxn.Payment]) -> None: ## E: unsupported type for an ARC-4 method
         pass
 
-    @arc4.abimethod ## E: invalid type for an ARC-4 method: algopy.ReferenceArray[algopy.itxn.PaymentInnerTransaction]
-    def arr_itxn2_arg(self, arr: ReferenceArray[itxn.PaymentInnerTransaction]) -> None:
+    @arc4.abimethod
+    def arr_itxn2_arg(self, arr: ReferenceArray[itxn.PaymentInnerTransaction]) -> None: ## E: unsupported type for an ARC-4 method
         pass
 
-    @arc4.abimethod ## E: invalid type for an ARC-4 method: algopy.ReferenceArray[algopy.Asset]
-    def arr_asset_arg(self, arr: ReferenceArray[Asset]) -> None:
+    @arc4.abimethod
+    def arr_asset_arg(self, arr: ReferenceArray[Asset]) -> None: ## E: unsupported type for an ARC-4 method
         pass
 
-    @arc4.abimethod ## E: invalid type for an ARC-4 method: algopy.ReferenceArray[algopy.Account]
-    def arr_account_arg(self, arr: ReferenceArray[Account]) -> None:
+    @arc4.abimethod
+    def arr_account_arg(self, arr: ReferenceArray[Account]) -> None: ## E: unsupported type for an ARC-4 method
         pass
 
-    @arc4.abimethod()
-    def test_reference_array_extend_with_arc4_bool(self) -> None:
-        arr = ReferenceArray[arc4.Bool]()
-        dyn_arr = arc4.DynamicArray[arc4.Bool]()
-        arr.extend(dyn_arr) ## E: extending a reference array with an ARC-4 encoded bool type is not supported
+    @arc4.abimethod ## E: unsupported return type for an ARC-4 method
+    def arr_account_return(self) -> ReferenceArray[Account]:
+        op.err("Not implemented")
+
 
 ## case: test_imm_array_txn
 from algopy import *