BUG: ImageIOBase should internally use signed char for CHAR
#5463
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`ImageIOBase::GetComponentTypeTraits` incorrectly assumed that the plain `char` type is always mapped to `IOComponentEnum::CHAR`. However, that isn't the case when the default `char` type is an unsigned type (as can be specified by GCC option `-funsigned-char` and MSVC option `/J`). This bug was introduced with pull request InsightSoftwareConsortium#5421 commit 3604e0c "ENH: Ease getting type traits of pixel components from ImageIO" (merged to the master branch on June 23, 2025). The bug caused incorrect return values from the following function calls: ImageIOBase::GetNumberOfBitsOfComponentType(IOComponentEnum::INT8); ImageIOBase::GetNumberOfBitsOfComponentType(IOComponentEnum::CHAR); ImageIOBase::GetComponentTypeFromTypeTraits(false, false, 0); ImageIOBase::GetComponentTypeFromTypeTraits(false, false, 8); As was observed from the static_assert failures in "itkImageIOBaseTest.cxx", when using the compiler option that makes the default `char` unsigned.
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dzenanz
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Jul 10, 2025
hjmjohnson
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ImageIOBase::GetComponentTypeTraitsincorrectly assumed that the plainchartype is always mapped toIOComponentEnum::CHAR. However, that isn't the case when the defaultchartype is an unsigned type (as can be specified by GCC option-funsigned-charand MSVC option/J).This bug was introduced with pull request #5421 commit 3604e0c "ENH: Ease getting type traits of pixel components from ImageIO" (merged to the master branch on June 23, 2025).
The bug caused incorrect return values from the following function calls:
As was observed from the static_assert failures in "itkImageIOBaseTest.cxx", when using the compiler option that makes the default
charunsigned.Note: The bug was my own fault 😺