[go] Teach the go cmake build functions to funnel the include directories down into the cgo-setup variables of llvm-go.

[chandlerc]

Summary

This in turn allows us to use #includes with cgo that rely on CMake
provided include directories which is particularly useful for handling
generated headers that aren't reasonable to put in an "installable"
location.

[pcc]

cmake/modules/AddLLVM.cmake

636 ↗

(On Diff #17676)

Are you sure you need to set cxxflags? As far as I know, cppflags should be picked up for C and C++.

[pcc]

(and LGTM once that is resolved)

llvm/trunk/cmake/modules/AddLLVM.cmake

function(llvm_add_go_executable binary pkgpath)
   cmake_parse_arguments(ARG "ALL" "" "DEPENDS;GOFLAGS" ${ARGN})
 
   if(LLVM_BINDINGS MATCHES "go")
     # FIXME: This should depend only on the libraries Go needs.
     get_property(llvmlibs GLOBAL PROPERTY LLVM_LIBS)
     set(binpath ${CMAKE_BINARY_DIR}/bin/${binary}${CMAKE_EXECUTABLE_SUFFIX})
     set(cc "${CMAKE_C_COMPILER} ${CMAKE_C_COMPILER_ARG1}")
     set(cxx "${CMAKE_CXX_COMPILER} ${CMAKE_CXX_COMPILER_ARG1}")
+    set(cppflags "")
+    get_property(include_dirs DIRECTORY PROPERTY INCLUDE_DIRECTORIES)
+    foreach(d ${include_dirs})
+      set(cppflags "${cppflags} -I${d}")
+    endforeach(d)
     set(ldflags "${CMAKE_EXE_LINKER_FLAGS}")
     add_custom_command(OUTPUT ${binpath}
-      COMMAND ${CMAKE_BINARY_DIR}/bin/llvm-go "cc=${cc}" "cxx=${cxx}" "ldflags=${ldflags}"
+      COMMAND ${CMAKE_BINARY_DIR}/bin/llvm-go "cc=${cc}" "cxx=${cxx}" "cppflags=${cppflags}" "ldflags=${ldflags}"
               ${ARG_GOFLAGS} build -o ${binpath} ${pkgpath}
       DEPENDS llvm-config ${CMAKE_BINARY_DIR}/bin/llvm-go${CMAKE_EXECUTABLE_SUFFIX}
               ${llvmlibs} ${ARG_DEPENDS}
       COMMENT "Building Go executable ${binary}"
       VERBATIM)
     if (ARG_ALL)
       add_custom_target(${binary} ALL DEPENDS ${binpath})
     else()