COMP: Fix COMPILE_DEPENDS → DEPENDS in three Filtering module declara…

[blowekamp]

…tions

ITKImageIntensity, ITKDenoising, and ITKDiffusionTensorImage declared their dependencies with COMPILE_DEPENDS instead of DEPENDS. COMPILE_DEPENDS only populates the legacy include_directories() path and does not call target_link_libraries(), so no CMake target link is established and INTERFACE_INCLUDE_DIRECTORIES cannot propagate transitively.

This breaks builds with system Eigen (ITK_USE_SYSTEM_EIGEN=ON): the Eigen3::Eigen include path is silently dropped, causing failures in headers such as itkSymmetricEigenAnalysis.h. Since these modules genuinely link against their listed dependencies, DEPENDS is semantically correct.

PR Checklist

• No API changes were made (or the changes have been approved)
• No major design changes were made (or the changes have been approved)
• Added test (or behavior not changed)
• Updated API documentation (or API not changed)
• Added license to new files (if any)
• Added Python wrapping to new files (if any) as described in ITK Software Guide Section 9.5
• Added ITK examples for all new major features (if any)

Refer to the ITK Software Guide for
further development details if necessary.

[blowekamp]

This issue was encountered when trying to build the conda-forge libitk-feedstock against the current ITK main. The build uses eigen provided by conda-forge.

[greptile-apps]

Greptile Summary

This PR fixes a build regression when ITK_USE_SYSTEM_EIGEN=ON by correcting three itk-module.cmake declarations that erroneously used COMPILE_DEPENDS instead of DEPENDS. COMPILE_DEPENDS only orders the build but does not call target_link_libraries(), so INTERFACE_INCLUDE_DIRECTORIES (e.g. the Eigen3::Eigen path) never propagated transitively, silently breaking headers like itkSymmetricEigenAnalysis.h.

The three one-word changes in ITKDenoising, ITKDiffusionTensorImage, and ITKImageIntensity are minimal and semantically correct. Note that 56 other itk-module.cmake files across the repository still use COMPILE_DEPENDS; those may or may not be intentional, and a broader audit could be worthwhile as follow-up.

Confidence Score: 5/5

Safe to merge — targeted, minimal fix for a real build failure with no behaviour change in standard builds.

All three changes are single-keyword corrections that restore correct CMake semantics (target linking vs. compile ordering). No API surface, no logic, no data flow is altered. The remaining 56 COMPILE_DEPENDS usages are out of scope for this PR and do not block merging.

No files require special attention; consider a follow-up audit of the 56 remaining COMPILE_DEPENDS usages in the repository.

Important Files Changed

Filename	Overview
Modules/Filtering/Denoising/itk-module.cmake	Changed COMPILE_DEPENDS → DEPENDS so ITKImageAdaptors, ITKImageGrid, ITKImageStatistics, ITKIOImageBase, and ITKStatistics are properly linked via target_link_libraries() and propagate INTERFACE_INCLUDE_DIRECTORIES transitively.
Modules/Filtering/DiffusionTensorImage/itk-module.cmake	Changed COMPILE_DEPENDS → DEPENDS for ITKSpatialObjects, establishing proper CMake target link and transitive include propagation for this module.
Modules/Filtering/ImageIntensity/itk-module.cmake	Changed COMPILE_DEPENDS → DEPENDS for ITKImageAdaptors, ITKImageStatistics, ITKImageGrid, and ITKPath — the fix that directly restores the Eigen3::Eigen include path when ITK_USE_SYSTEM_EIGEN=ON.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["itk_module() with COMPILE_DEPENDS\n(before fix)"] -->|"add_dependencies() only"| B["Module is built after dependency\n(ordering guarantee only)"]
    B --> C["target_link_libraries() NOT called"]
    C --> D["INTERFACE_INCLUDE_DIRECTORIES\nnot propagated transitively"]
    D --> E["❌ Eigen3::Eigen include path missing\n→ build failure with ITK_USE_SYSTEM_EIGEN=ON"]

    F["itk_module() with DEPENDS\n(after fix)"] -->|"add_dependencies() + target_link_libraries()"| G["Module is built after dependency\n(ordering guarantee)"]
    G --> H["INTERFACE_INCLUDE_DIRECTORIES\npropagated transitively"]
    H --> I["✅ Eigen3::Eigen include path available\n→ itkSymmetricEigenAnalysis.h compiles correctly"]

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