Build: llvm-config --system-libs needs --static for LLVM_STATIC (#1375)

This fixes CI in the Mac test. Something about the Homebrew upgrade to llvm 12.0.0_1 made this fix necessary to build.

Signed-off-by: Larry Gritz <[email protected]>

Author: lgritz

src/cmake/modules/FindLLVM.cmake

@@ -58,9 +58,35 @@ execute_process (COMMAND ${LLVM_CONFIG} --includedir
 execute_process (COMMAND ${LLVM_CONFIG} --targets-built
        OUTPUT_VARIABLE LLVM_TARGETS
        OUTPUT_STRIP_TRAILING_WHITESPACE)
-execute_process (COMMAND ${LLVM_CONFIG} --system-libs
-                 OUTPUT_VARIABLE LLVM_SYSTEM_LIBRARIES
-                 OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+############ HACK ##############
+# On OSX, the Homebrew (and maybe any build) of LLVM 10.0 seems to have a
+# link conflict with its dependency on the llvm libc++ and the system
+# libc++, both can end up dynamically linked and lead to very subtle and
+# frustrating behavior failures (in particular, osl's use of libclang will
+# botch include file parsing any time LD_LIBRARY_PATH doesn't have the llvm
+# libc++ first).
+#
+# It seems that this is not a problem when linking against the llvm and
+# libclang libraries statically. So on apple and when LLVM 10+ are involved,
+# just force that choice. Other than larger executables, it seems harmless,
+# and in any case a better choice than this beastly bug.
+#
+# We can periodically revisit this with new version of LLVM, maybe they will
+# fix things and we won't require this preemptive static linking.
+if (APPLE AND LLVM_VERSION VERSION_GREATER_EQUAL 10.0)
+    set (LLVM_STATIC ON)
+endif ()
+
+if (LLVM_STATIC)
+    execute_process (COMMAND ${LLVM_CONFIG} --system-libs --link-static
+                     OUTPUT_VARIABLE LLVM_SYSTEM_LIBRARIES
+                     OUTPUT_STRIP_TRAILING_WHITESPACE)
+else ()
+    execute_process (COMMAND ${LLVM_CONFIG} --system-libs
+                     OUTPUT_VARIABLE LLVM_SYSTEM_LIBRARIES
+                     OUTPUT_STRIP_TRAILING_WHITESPACE)
+endif ()
 string (REPLACE " " ";" LLVM_SYSTEM_LIBRARIES "${LLVM_SYSTEM_LIBRARIES}")
 
 find_library ( LLVM_LIBRARY
@@ -105,25 +131,6 @@ foreach (COMPONENT clangFrontend clangDriver clangSerialization
 endforeach ()
 
 
-############ HACK ##############
-# On OSX, the Homebrew (and maybe any build) of LLVM 10.0 seems to have a
-# link conflict with its dependency on the llvm libc++ and the system
-# libc++, both can end up dynamically linked and lead to very subtle and
-# frustrating behavior failures (in particular, osl's use of libclang will
-# botch include file parsing any time LD_LIBRARY_PATH doesn't have the llvm
-# libc++ first).
-#
-# It seems that this is not a problem when linking against the llvm and
-# libclang libraries statically. So on apple and when LLVM 10+ are involved,
-# just force that choice. Other than larger executables, it seems harmless,
-# and in any case a better choice than this beastly bug.
-#
-# We can periodically revisit this with new version of LLVM, maybe they will
-# fix things and we won't require this preemptive static linking.
-if (APPLE AND LLVM_VERSION VERSION_GREATER_EQUAL 10.0)
-    set (LLVM_STATIC ON)
-endif ()
-
 # shared llvm library may not be available, this is not an error if we use LLVM_STATIC.
 if ((LLVM_LIBRARY OR LLVM_LIBRARIES OR LLVM_STATIC) AND LLVM_INCLUDES AND LLVM_DIRECTORY AND LLVM_LIB_DIR)
   if (LLVM_STATIC)