diff -ur extra-cmake-modules-v6.31.0.orig/kde-modules/KDECompilerSettings.cmake extra-cmake-modules-v6.31.0/kde-modules/KDECompilerSettings.cmake
--- extra-cmake-modules-v6.31.0.orig/kde-modules/KDECompilerSettings.cmake	2026-09-30 11:32:40.000000000 -0500
+++ extra-cmake-modules-v6.31.0/kde-modules/KDECompilerSettings.cmake	2026-10-25 22:39:46.864644526 -0500
@@ -432,10 +432,17 @@
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-operator-names")
 endif()
 
-# Default to hidden visibility for symbols
-set(CMAKE_C_VISIBILITY_PRESET hidden)
-set(CMAKE_CXX_VISIBILITY_PRESET hidden)
-set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
+if (CMAKE_SYSTEM_NAME STREQUAL "SunOS")
+    # on Illumos and SunOS, default to default visibility
+    set(CMAKE_C_VISIBILITY_PRESET default)
+    set(CMAKE_CXX_VISIBILITY_PRESET default)
+    set(CMAKE_VISIBILITY_INLINES_HIDDEN 0)
+else()
+    # other platforms get hidden visibility
+    set(CMAKE_C_VISIBILITY_PRESET hidden)
+    set(CMAKE_CXX_VISIBILITY_PRESET hidden)
+    set(CMAKE_VISIBILITY_INLINES_HIDDEN 1)
+endif()
 if (POLICY CMP0063)
     # No sane project should be affected by CMP0063, so suppress the warnings
     # generated by the above visibility settings in CMake >= 3.3
@@ -445,9 +452,12 @@
 if (UNIX AND NOT APPLE AND NOT CYGWIN)
     # Enable adding DT_RUNPATH, which means that LD_LIBRARY_PATH takes precedence
     # over the built-in rPath
-    set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--enable-new-dtags ${CMAKE_SHARED_LINKER_FLAGS}")
-    set(CMAKE_MODULE_LINKER_FLAGS "-Wl,--enable-new-dtags ${CMAKE_MODULE_LINKER_FLAGS}")
-    set(CMAKE_EXE_LINKER_FLAGS    "-Wl,--enable-new-dtags ${CMAKE_EXE_LINKER_FLAGS}")
+    if (NOT CMAKE_SYSTEM_NAME STREQUAL "SunOS")
+        # don't apply on Illumos
+        set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--enable-new-dtags ${CMAKE_SHARED_LINKER_FLAGS}")
+        set(CMAKE_MODULE_LINKER_FLAGS "-Wl,--enable-new-dtags ${CMAKE_MODULE_LINKER_FLAGS}")
+        set(CMAKE_EXE_LINKER_FLAGS    "-Wl,--enable-new-dtags ${CMAKE_EXE_LINKER_FLAGS}")
+    endif()
 endif()
 
 if (CMAKE_SYSTEM_NAME STREQUAL GNU)
@@ -564,8 +574,11 @@
         (CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND NOT APPLE) OR
         (CMAKE_CXX_COMPILER_ID STREQUAL "Intel" AND NOT WIN32))
     # Linker warnings should be treated as errors
-    set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--fatal-warnings ${CMAKE_SHARED_LINKER_FLAGS}")
-    set(CMAKE_MODULE_LINKER_FLAGS "-Wl,--fatal-warnings ${CMAKE_MODULE_LINKER_FLAGS}")
+    if (NOT CMAKE_SYSTEM_NAME STREQUAL "SunOS")
+        # .. but not on Illumos
+        set(CMAKE_SHARED_LINKER_FLAGS "-Wl,--fatal-warnings ${CMAKE_SHARED_LINKER_FLAGS}")
+        set(CMAKE_MODULE_LINKER_FLAGS "-Wl,--fatal-warnings ${CMAKE_MODULE_LINKER_FLAGS}")
+    endif()
 
     string(TOUPPER "CMAKE_CXX_FLAGS_${CMAKE_BUILD_TYPE}" compileflags)
     if("${CMAKE_CXX_FLAGS} ${${compileflags}}" MATCHES "-fsanitize")
@@ -577,8 +590,11 @@
     # Do not allow undefined symbols, even in non-symbolic shared libraries
     # On OpenBSD we must disable this to allow the stuff to properly compile without explicit libc specification
     if (NOT CMAKE_SYSTEM_NAME MATCHES "OpenBSD" AND (NOT sanitizers_enabled OR NOT CMAKE_CXX_COMPILER_ID MATCHES "Clang"))
-        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 CMAKE_SYSTEM_NAME STREQUAL "SunOS")
+            # don't defeine this on Illumos either
+            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()
 endif()