Correct behavior of tablegen cmake linking on llvm shared builds (rust-lang#833)

* Conditional check for tbl linked libs

* Better not found check

* Fix

* Fix

Author: wsmoses

enzyme/Enzyme/CMakeLists.txt

@@ -7,8 +7,11 @@ if ("${Enzyme_TABLEGEN_EXE}" STREQUAL "")
 endif()
 
 get_target_property(TBL_LINKED_LIBS LLVMSupport INTERFACE_LINK_LIBRARIES)
+if (NOT TBL_LINKED_LIBS)
+else()
 list(REMOVE_ITEM TBL_LINKED_LIBS "ZLIB::ZLIB")
 set_property(TARGET LLVMSupport PROPERTY INTERFACE_LINK_LIBRARIES ${TBL_LINKED_LIBS})
+endif()
 
 function(enzyme_tablegen ofn)
   if (${LLVM_VERSION_MAJOR} GREATER 11)

enzyme/tools/enzyme-tblgen/CMakeLists.txt

@@ -10,6 +10,11 @@ add_tablegen(enzyme-tblgen Enzyme
   enzyme-tblgen.cpp
   )
 
+get_target_property(TBL_LINKED_LIBS LLVMSupport INTERFACE_LINK_LIBRARIES)
+if (NOT TBL_LINKED_LIBS)
+    target_link_libraries(enzyme-tblgen PUBLIC "stdc++")
+endif()
+
 set_target_properties(enzyme-tblgen PROPERTIES FOLDER "Tablegenning")
 target_link_libraries(enzyme-tblgen
   PRIVATE)