BUG: raise a clear error in common_type for non-array input#31592
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Lawson-Darrow wants to merge 1 commit into
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BUG: raise a clear error in common_type for non-array input#31592Lawson-Darrow wants to merge 1 commit into
Lawson-Darrow wants to merge 1 commit into
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common_type does a.dtype.type on each input, so passing a dtype or a
scalar type like np.common_type(np.dtype("f4")) raised a confusing
AttributeError. Catch that case and raise a TypeError that tells the
user to reach for np.result_type or np.promote_types instead. Valid
array inputs are unchanged.
Closes numpygh-30890
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Fixes #30890
Summary
numpy.common_typedoesa.dtype.typeon each input so passing a dtype or a scalar type, for examplenp.common_type(np.dtype("f4")), raised a confusingAttributeError('numpy.dtypes.Float32DType' object has no attribute 'dtype').This catches that case and raises a
TypeErrorthat points tonp.result_typeandnp.promote_typeswhich are the tools meant for combining dtypes and scalar types. A dtype instance is shown asdtype('float32')and a scalar type as'float32'. Valid array inputs are unchanged. This follows the direction @ngoldbaum and @seberg suggested on the issue.Before:
After:
Test plan
Added tests in
numpy/lib/tests/test_type_check.pyfor dtype and scalar-type inputs: a clearTypeErrorwith thenp.result_type/np.promote_typesguidance, the dtype instance shown asdtype('float32'), and the scalar type as'float32'. ExistingTestCommonType.test_basicstill covers real arrays. Release note added indoc/release/upcoming_changes/30890.improvement.rst.This change was prepared with AI assistance (Claude Code, OpenAI Codex). I reviewed and verified the change and the tests locally and take responsibility for it.