COMP: Use single export() call to fix namespace corruption - #3
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blowekamp merged 1 commit intoJul 14, 2026
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Replacing three APPEND export() calls with one non-APPEND call fixes a namespace corruption bug where CMake prepends the DCMTK:: namespace to dependency targets (e.g. ITK codec targets) that belong to other export sets. CMake's HandleMissingTarget only searches other registered export sets when not in append mode. In append mode it blindly prepends the current namespace, producing DCMTK::ITK::ITKZLIBModule instead of the correct ITK::ITKZLIBModule in DCMTKTargets.cmake. The file(WRITE)+3xAPPEND pattern was used only to accumulate targets across multiple calls; combining them into a single export() call is equivalent and avoids the append-mode shortcut.
dzenanz
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Looks good to me. Do you have an upstream PR for this?
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DCMTK's GenerateCMakeExports.cmake wrote DCMTKTargets.cmake with three export(APPEND) calls; CMake's append mode skips the cross-export-set namespace lookup and blindly prefixes DCMTK:: onto ITK's codec targets, recording the nonexistent DCMTK::ITK::ITKZLIBModule (and TIFF/JPEG/PNG). An external consumer of an ITK build tree then fails at generate. The pinned InsightSoftwareConsortium/DCMTK#3 merges the exports into a single export() call so foreign targets resolve to their ITK:: names. Root cause analysis and DCMTK fix by Bradley Lowekamp.
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@hjmjohnson Were you able to build the ITK forest successfuly with this patch? @dzenanz Once we confirm it fixes the issue for ITK, we can make a PR upstream. |
blowekamp
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DCMTK's GenerateCMakeExports.cmake wrote DCMTKTargets.cmake with three export(APPEND) calls; CMake's append mode skips the cross-export-set namespace lookup and blindly prefixes DCMTK:: onto ITK's codec targets, recording the nonexistent DCMTK::ITK::ITKZLIBModule (and TIFF/JPEG/PNG). An external consumer of an ITK build tree then fails at generate. The pinned InsightSoftwareConsortium/DCMTK#3 merges the exports into a single export() call so foreign targets resolve to their ITK:: names. Root cause analysis and DCMTK fix by Bradley Lowekamp.
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PR made upstream DCMTK#154 |
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Replacing the three
APPENDexport()calls with a single non-APPENDcall fixes a namespace corruption bug inDCMTKTargets.cmake.Root cause
CMake's
cmExportBuildFileGenerator::HandleMissingTargethas two code paths for dependency targets not in the current export set:FindExportInfo(), which searches all registered build export sets. If the dependency is found in exactly one other set with one namespace, that namespace is used — e.g.ITK::ITKZLIBModule.APPEND): skips the lookup and blindly prepends the current export's namespace, producingDCMTK::ITK::ITKZLIBModule.The previous
file(WRITE) + 3×export(APPEND)pattern was used only to accumulate targets across multiple calls. All three calls share the sameNAMESPACE DCMTK::, so combining them into a singleexport()is equivalent — and avoids triggering the append-mode shortcut.Observed bug in ITK's FetchContent build
When DCMTK is consumed in-scope via FetchContent (as ITK does),
DCMTKTargets.cmakecontained:The
DCMTK::prefix was incorrectly prepended to the already-namespaced ITK codec targets. After this fix:See InsightSoftwareConsortium/ITK#6548 for context.