add L4Bender linker in all relevant scenarios

Author: humenda

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -82,7 +82,7 @@ impl LinkerInfo {
                     cmd,
                     sess,
                     hinted_static: false,
-                }) as Box<Linker>
+                }) as Box<dyn Linker>
             },
             LinkerFlavor::Lld(LldFlavor::Wasm) => {
                 Box::new(WasmLd::new(cmd, sess, self)) as Box<dyn Linker>
@@ -1401,6 +1401,9 @@ impl<'a> Linker for L4Bender<'a> {
 
     fn group_start(&mut self) { self.cmd.arg("--start-group"); }
     fn group_end(&mut self) { self.cmd.arg("--end-group"); }
+    fn cross_lang_lto(&mut self) {
+        // do nothing
+    }
 }
 
 impl<'a> L4Bender<'a> {

compiler/rustc_target/src/spec/mod.rs

@@ -90,6 +90,7 @@ mod windows_uwp_msvc_base;
 pub enum LinkerFlavor {
     Em,
     Gcc,
+    L4Bender,
     Ld,
     Msvc,
     Lld(LldFlavor),
@@ -160,6 +161,7 @@ macro_rules! flavor_mappings {
 flavor_mappings! {
     ((LinkerFlavor::Em), "em"),
     ((LinkerFlavor::Gcc), "gcc"),
+    ((LinkerFlavor::L4Bender), "l4-bender"),
     ((LinkerFlavor::Ld), "ld"),
     ((LinkerFlavor::Msvc), "msvc"),
     ((LinkerFlavor::PtxLinker), "ptx-linker"),