LLVM-C needed but isn't supported on Linux

[boberfly]

Hi,

I noticed that LLVM-C isn't built for Linux and it is a requirement of shady. I tried building my own LLVM via -DLLVM_BUILD_LLVM_C_DYLIB=ON however I get:

CMake Error at tools/llvm-shlib/CMakeLists.txt:86 (message):
  Generating libLLVM-c is only supported on Darwin

Is this a hard-requirement? Do I need to patch the CMake to force it to build for linux?

Kind regards

[boberfly]

If anyone is wanting to do this at home, I made a patch against LLVM 19.1.7 here:

--- a/llvm/tools/llvm-shlib/CMakeLists.txt	2024-09-17 21:26:36.000000000 +1000
+++ b/llvm/tools/llvm-shlib/CMakeLists.txt	2025-10-04 17:57:11.000000000 +1000
@@ -82,9 +82,9 @@
 endif()
 
 if(LLVM_BUILD_LLVM_C_DYLIB AND NOT MSVC)
-  if(NOT APPLE)
-    message(FATAL_ERROR "Generating libLLVM-c is only supported on Darwin")
-  endif()
+  #if(NOT APPLE)
+  #  message(FATAL_ERROR "Generating libLLVM-c is only supported on Darwin")
+  #endif()
 
   if(NOT LLVM_BUILD_LLVM_DYLIB)
     message(FATAL_ERROR "Generating libLLVM-c requires LLVM_BUILD_LLVM_C_DYLIB on Darwin")
@@ -115,9 +115,11 @@
   target_link_libraries(LLVM-C PUBLIC LLVM)
   add_dependencies(LLVM-C libLLVMCExports)
 
-  set_property(TARGET LLVM-C APPEND_STRING PROPERTY
-              LINK_FLAGS
-              " -compatibility_version 1 -current_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH} -Wl,-reexport_library ${LIB_PATH}")
+  if (APPLE)
+    set_property(TARGET LLVM-C APPEND_STRING PROPERTY
+                LINK_FLAGS
+                " -compatibility_version 1 -current_version ${LLVM_VERSION_MAJOR}.${LLVM_VERSION_MINOR}.${LLVM_VERSION_PATCH} -Wl,-reexport_library ${LIB_PATH}")
+  endif()
 endif()
 
 if(LLVM_BUILD_LLVM_C_DYLIB AND MSVC)

[Hugobros3]

No, the LLVM-C component is available in the libLLVM shared library, and shady supports both. Also, you can use your distribution's llvm-devel packages in most cases