Address PR zarr-developers#3534 review comments

- Fix _info() crash for RectilinearChunkGrid arrays by catching
  NotImplementedError from metadata.chunks (displays "<variable>")
- Fix spurious FutureWarning in _nchunks_initialized() by using
  array.metadata.chunks instead of array.chunks
- Add empty-chunk validation in _normalize_rectilinear_chunks to reject
  chunk specs where the last chunk(s) contain no valid data
- Remove FutureWarning deprecation on .chunks for RegularChunkGrid per
  reviewer feedback; .chunks still raises NotImplementedError for
  RectilinearChunkGrid

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jhamman

src/zarr/core/array.py

@@ -1070,15 +1070,11 @@ def chunk_grid(self) -> ChunkGrid:
     def chunks(self) -> tuple[int, ...]:
         """Returns the chunk shape of the Array.
 
-        .. deprecated::
-            The `chunks` property is deprecated and will be removed in a future version.
-            Use `chunk_grid` instead to access chunk information.
-
         For arrays using RegularChunkGrid: returns a tuple of ints with uniform chunk sizes.
         If sharding is used, the inner chunk shape is returned.
 
         For arrays using RectilinearChunkGrid: raises NotImplementedError as variable chunks
-        cannot be represented as a simple tuple.
+        cannot be represented as a simple tuple. Use ``chunk_grid`` instead.
 
         Returns
         -------
@@ -1096,12 +1092,6 @@ def chunks(self) -> tuple[int, ...]:
                 "(RectilinearChunkGrid). Use `chunk_grid` instead to access chunk information."
             )
             raise NotImplementedError(msg)
-        warnings.warn(
-            "Array.chunks is deprecated and will be removed in a future version. "
-            "Use Array.chunk_grid.chunk_shape instead.",
-            FutureWarning,
-            stacklevel=2,
-        )
         return self.metadata.chunks
 
     @property
@@ -1990,14 +1980,18 @@ async def info_complete(self) -> Any:
     def _info(
         self, count_chunks_initialized: int | None = None, count_bytes_stored: int | None = None
     ) -> Any:
+        try:
+            chunk_shape: tuple[int, ...] | None = self.metadata.chunks
+        except NotImplementedError:
+            chunk_shape = None
         return ArrayInfo(
             _zarr_format=self.metadata.zarr_format,
             _data_type=self._zdtype,
             _fill_value=self.metadata.fill_value,
             _shape=self.shape,
             _order=self.order,
             _shard_shape=self.shards,
-            _chunk_shape=self.chunks,
+            _chunk_shape=chunk_shape,
             _read_only=self.read_only,
             _compressors=self.compressors,
             _filters=self.filters,
@@ -2342,15 +2336,11 @@ def chunk_grid(self) -> ChunkGrid:
     def chunks(self) -> tuple[int, ...]:
         """Returns the chunk shape of the Array.
 
-        .. deprecated::
-            The `chunks` property is deprecated and will be removed in a future version.
-            Use `chunk_grid` instead to access chunk information.
-
         For arrays using RegularChunkGrid: returns a tuple of ints with uniform chunk sizes.
         If sharding is used, the inner chunk shape is returned.
 
         For arrays using RectilinearChunkGrid: raises NotImplementedError as variable chunks
-        cannot be represented as a simple tuple.
+        cannot be represented as a simple tuple. Use ``chunk_grid`` instead.
 
         Returns
         -------
@@ -5734,7 +5724,7 @@ async def _nchunks_initialized(
         chunks_per_shard = 1
     else:
         chunks_per_shard = product(
-            tuple(a // b for a, b in zip(array.shards, array.chunks, strict=True))
+            tuple(a // b for a, b in zip(array.shards, array.metadata.chunks, strict=True))
         )
     return (await _nshards_initialized(array)) * chunks_per_shard
 

src/zarr/core/chunk_grids.py

@@ -1397,6 +1397,12 @@ def _normalize_rectilinear_chunks(
                 f"Variable chunks along dimension {i} sum to {chunk_sum} "
                 f"but array shape is {dim_size}. Chunks must sum to be greater than or equal to the shape."
             )
+        if sum(dim_chunks[:-1]) >= dim_size:
+            raise ValueError(
+                f"Dimension {i} has more chunks than needed. "
+                f"The last chunk(s) would contain no valid data. "
+                f"Remove the extra chunk(s) or increase the array shape."
+            )
 
     return chunk_shapes
 

tests/test_chunk_grids/test_rectilinear.py

@@ -1326,10 +1326,8 @@ def test_sync_array_chunks_property_rectilinear_raises() -> None:
     assert chunk_grid.chunk_shapes == ((10, 20, 30, 40), (25, 25, 50))
 
 
-async def test_array_chunks_property_regular_with_warning() -> None:
-    """Test that Array.chunks emits FutureWarning for RegularChunkGrid."""
-    import warnings
-
+async def test_array_chunks_property_regular() -> None:
+    """Test that Array.chunks works for RegularChunkGrid."""
     store = MemoryStore()
 
     arr = await zarr.api.asynchronous.create_array(
@@ -1340,20 +1338,13 @@ async def test_array_chunks_property_regular_with_warning() -> None:
         zarr_format=3,
     )
 
-    # chunks should emit FutureWarning for regular grids
-    with warnings.catch_warnings(record=True) as w:
-        warnings.simplefilter("always")
-        chunks = arr.chunks
-        assert len(w) == 1
-        assert issubclass(w[0].category, FutureWarning)
-        assert "deprecated" in str(w[0].message)
-
-    # For regular chunks, it's tuple[int, ...]
+    # For regular chunks, returns tuple[int, ...]
+    chunks = arr.chunks
     assert chunks == (10, 20)
     assert isinstance(chunks[0], int)
     assert isinstance(chunks[1], int)
 
-    # chunk_grid.chunk_shape works without warning
+    # chunk_grid.chunk_shape also works
     chunk_grid = arr.chunk_grid
     assert isinstance(chunk_grid, RegularChunkGrid)
     assert chunk_grid.chunk_shape == (10, 20)