[PATCH] D134165: [llvm] prefix linker flag on non-MSVC compilers with `-Wl,`

[Ashay Rane via Phabricator via llvm-commits]

ashay-github created this revision.
ashay-github added reviewers: rnk, beanz, stella.stamenova.
Herald added a project: All.
ashay-github requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Prior to this patch, a Windows build of llvm-lto using clang failed with
the error: `LTO.def: unknown file type`.  The reason for this failure is
that .DEF files are used by the linker not by the clang compiler.  The
MSVC compiler+linker handles this transparently, but if we're using
clang (or gcc), then we need to tell the compiler to forward this flag
to the linker. This patch adds the necessary `-Wl` flag to fix the
problem.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D134165

Files:
  llvm/cmake/modules/AddLLVM.cmake


Index: llvm/cmake/modules/AddLLVM.cmake
===================================================================
--- llvm/cmake/modules/AddLLVM.cmake
+++ llvm/cmake/modules/AddLLVM.cmake
@@ -130,6 +130,10 @@
     set(export_file_linker_flag "${CMAKE_CURRENT_BINARY_DIR}/${native_export_file}")
     if(MSVC)
       set(export_file_linker_flag "/DEF:\"${export_file_linker_flag}\"")
+    elseif(WIN32)
+      # If we're compiling on Windows and the compiler is not Visual Studio,
+      # then tell it to forward the `/DEF` flag to the linker.
+      set(export_file_linker_flag "-Wl,/DEF:\"${export_file_linker_flag}\"")
     endif()
     set_property(TARGET ${target_name} APPEND_STRING PROPERTY
                  LINK_FLAGS " ${export_file_linker_flag}")


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