Fixed typing of Construct._build().

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## [Unreleased]
+**Fixes:**
+- Fixed return type of `Construct._build()`: `int` was wrong and worked only in specific cases.
+
 ## [0.8.1] - 2026-07-23
 **New features:**
 - Added `Subconstruct`, `SymmetricAdapter`, `Tunnel` and `Validator` to `construct_typed` as subscriptable types.
@@ -23,4 +27,4 @@
 - Use PEP604 union syntax "X | Y" instead of "Union[X, Y]" and "X | None" instead of "Optional[X]" in type hints.
 
 **Organizational changes:**
-- Use `uv` as a project management tool and `poe` as a task runner.
+- Use `uv` as a project management tool and `poe` as a task runner.

construct-stubs/core.pyi

@@ -164,9 +164,11 @@ class Construct(t.Generic[ParsedType, BuildTypes]):
     def _parsereport(
         self, stream: StreamType, context: Context, path: PathType
     ) -> ParsedType: ...
+    # In most implementations, `_build()` actually returns `ParsedType`, in some others it
+    # returns `BuildTypes` or something else entirely. `t.Any` seems a good compromise.
     def _build(
         self, obj: BuildTypes, stream: StreamType, context: Context, path: PathType
-    ) -> int: ...
+    ) -> t.Any: ...
     def _sizeof(self, context: Context, path: PathType) -> int: ...
 
 @t.type_check_only

tests/test_core.py

@@ -1781,6 +1781,16 @@ def __init__(
                 hashfunc: t.Callable[[bytes], BuildTypes],
                 bytesfunc: t.Callable[[Context], bytes],
             ) -> None: ...
+
+            def _parse(self, stream: t.IO[bytes], context: Context, path: str) -> ParsedType:
+                ...
+
+            def _build(self, obj: BuildTypes, stream: t.IO[bytes], context: Context, path: str) -> t.Any:
+                ...
+
+            def _sizeof(self, context: Context, path: str) -> int:
+                ...
+
     else:
         import binascii