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COMP: Suppress macOS linker warnings for duplicate -lm from ITK dependencies #1376

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Merged
jamesobutler merged 1 commit into from
Mar 28, 2026
Merged

COMP: Suppress macOS linker warnings for duplicate -lm from ITK dependencies #1376

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14 changes: 14 additions & 0 deletions CMakeExternals/ITK.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,19 @@ if(NOT DEFINED ITK_DIR AND NOT ${CMAKE_PROJECT_NAME}_USE_SYSTEM_${proj})
GIT_TAG ${revision_tag})
endif()

# On macOS, Apple's linker warns about duplicate -lm entries that arise from
# ITK's transitive dependency chains. The duplicates are harmless (the linker
# deduplicates them) but produce ~70 warnings per build. Suppress them at the
# linker level since the fix belongs upstream in ITK's exported targets.
set(_itk_extra_linker_flags)
if(APPLE)
set(_itk_extra_linker_flags
-DCMAKE_SHARED_LINKER_FLAGS:STRING=-Wl,-no_warn_duplicate_libraries
-DCMAKE_EXE_LINKER_FLAGS:STRING=-Wl,-no_warn_duplicate_libraries
-DCMAKE_MODULE_LINKER_FLAGS:STRING=-Wl,-no_warn_duplicate_libraries
)
endif()

ExternalProject_Add(${proj}
${${proj}_EXTERNAL_PROJECT_ARGS}
SOURCE_DIR ${CMAKE_BINARY_DIR}/${proj}
Expand All @@ -59,6 +72,7 @@ if(NOT DEFINED ITK_DIR AND NOT ${CMAKE_PROJECT_NAME}_USE_SYSTEM_${proj})
INSTALL_COMMAND ""
CMAKE_CACHE_ARGS
${ep_common_cache_args}
${_itk_extra_linker_flags}
-DBUILD_EXAMPLES:BOOL=OFF
-DBUILD_SHARED_LIBS:BOOL=ON
-DITK_LEGACY_REMOVE:BOOL=ON
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11 changes: 11 additions & 0 deletions CMakeLists.txt
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Expand Up @@ -1231,6 +1231,17 @@ set(CMAKE_C_FLAGS ${CTK_C_FLAGS} CACHE STRING "CMake CXX Flags" FORCE)

set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS_INIT} ${CTK_EXE_LINKER_FLAGS}" CACHE STRING "Flags used when linking executables" FORCE)

# On macOS, Apple's linker warns about duplicate -lm entries inherited from
# external dependencies (notably ITK) via transitive target_link_libraries
# chains. The duplicates are harmless but produce spurious warnings.
if(APPLE)
foreach(_flag_var CMAKE_SHARED_LINKER_FLAGS CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS)
if(NOT "${${_flag_var}}" MATCHES "no_warn_duplicate_libraries")
set(${_flag_var} "${${_flag_var}} -Wl,-no_warn_duplicate_libraries" CACHE STRING "" FORCE)
endif()
endforeach()
endif()

#-----------------------------------------------------------------------------
# Set the header template which defines custom export/import macros
# for shared libraries
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