The message read odd with the missing be

OpenBSD has a similar patch inside the ports, see

Allow KDE5 libraries to be built without having to link to libc explicitly.
Index: kde-modules/KDECompilerSettings.cmake
--- kde-modules/KDECompilerSettings.cmake.orig
+++ kde-modules/KDECompilerSettings.cmake
@@ -530,6 +530,8 @@ endfunction()
 # Better diagnostics (warnings, errors)
 ############################################################

+set(ALLOW_UNDEFINED_LIB_SYMBOLS No CACHE BOOL "allow undefined symbols in generated shared objects")
+
 if ((CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT APPLE) OR
         (CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND NOT APPLE) OR
         (CMAKE_CXX_COMPILER_ID STREQUAL "Intel" AND NOT WIN32))
@@ -537,9 +539,11 @@ if ((CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT APPL
     set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--fatal-warnings ${CMAKE_SHARED_LINKER_FLAGS}")
     set(CMAKE_MODULE_LINKER_FLAGS "-Wl,--fatal-warnings ${CMAKE_MODULE_LINKER_FLAGS}")

-    # Do not allow undefined symbols, even in non-symbolic shared libraries
-    set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--no-undefined ${CMAKE_SHARED_LINKER_FLAGS}")
-    set(CMAKE_MODULE_LINKER_FLAGS "-Wl,--no-undefined ${CMAKE_MODULE_LINKER_FLAGS}")
+    if (NOT ${ALLOW_UNDEFINED_LIB_SYMBOLS})
+        # Do not allow undefined symbols, even in non-symbolic shared libraries
+        set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--no-undefined ${CMAKE_SHARED_LINKER_FLAGS}")
+        set(CMAKE_MODULE_LINKER_FLAGS "-Wl,--no-undefined ${CMAKE_MODULE_LINKER_FLAGS}")
+    endif()
 endif()

 set(_KDE_GCC_COMMON_WARNING_FLAGS "-Wall -Wextra -Wcast-align -Wchar-subscripts -Wformat-security -Wno-long-long -Wpointer-arith -Wundef")

Given ECM is released tightly bundled with KF, which itself requires
Qt 5.15 now, and no Linux distribution is known by repology.org which
ships older Qt, but current ECM, that support is considered of no more use.

Given ECM is released tighly bundled with KF, which itself requires
Qt 5.15 now, and no Linux distribution is known by repology.org which
ships older Qt, but current ECM, that support is considered of no more use.

The use of set_package_properties() requires the include, which might
not have been done by the macro consumer.

If the module is not included, the current message would be misleading.

Including the module by default is undesirable, because we print out a warning
that we do not override an existing module. While this warning is reasonable in most
cases, it is annoying for projects that have a custom clang-format file.

Checking if a .clang-format file exists and if not including KDEClangFormat is fragile,
because it depends on the include order of the modules.

Considering all that, a proper warning with instructions on how to fix the issue
is IMHO the best way to go.

I was getting CMake errors in repositories that had a pre-existing commit
hook: `string sub-command FIND requires 3 or 4 parameters.`
Adding quotes around the variables from 6224e7b8c28d434b81a19ac47b88cb58fee9d7d5
fixes this issue for me.