gn build: Fix `lld-link: unknown flag: -fuse-ld=lld` warnings on Windows

[thakis]

Summary

Fixes a minor regression from r351248.

[ruiu]

LGTM

[pcc]

LGTM

(Hmm, where's lld-link coming from? Ah, http://llvm-cs.pcc.me.uk/utils/gn/build/toolchain/BUILD.gn#200 . Maybe that should be using use_lld?)

[thakis]

In D57342#1374050, @pcc wrote:

LGTM

(Hmm, where's lld-link coming from? Ah, http://llvm-cs.pcc.me.uk/utils/gn/build/toolchain/BUILD.gn#200 . Maybe that should be using use_lld?)

You mean like

if (clang_base_path != "") {
  cl = "$clang_base_path/bin/clang-cl"
  if (use_lld) {
    link = "$clang_base_path/bin/lld-link"
  }
}

?

[pcc]

In D57342#1374102, @thakis wrote:

In D57342#1374050, @pcc wrote:

LGTM

(Hmm, where's lld-link coming from? Ah, http://llvm-cs.pcc.me.uk/utils/gn/build/toolchain/BUILD.gn#200 . Maybe that should be using use_lld?)

You mean like

if (clang_base_path != "") {
  cl = "$clang_base_path/bin/clang-cl"
  if (use_lld) {
    link = "$clang_base_path/bin/lld-link"
  }
}

?

Yes.

[thakis]

Makes sense, will land with that.

Thanks!

[thakis]

Landed in r352415, but forgot to put in the "Differential Revision:" line.

llvm/utils/gn/build/BUILD.gn

if (host_os == "win" && !is_clang) {
     }
     if (is_clang && use_goma) {
       # goma converts all paths to lowercase on the server, breaking this
       # warning.
       cflags += [ "-Wno-nonportable-include-path" ]
     }
   }
 
-  if (use_lld) {
+  # On Windows, the linker is not invoked through the compiler driver.
+  if (use_lld && host_os != "win") {
     ldflags += [ "-fuse-ld=lld" ]
   }
 }
 
 config("no_rtti") {
   if (current_os == "win") {
     cflags_cc = [ "/GR-" ]
   } else {