Reduce dependence on the target name

The target name can be anything with custom target specs. Matching on
fields inside the target spec is much more robust than matching on the
target name.

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -85,11 +85,7 @@ pub fn link_binary(
         }
 
         if invalid_output_for_target(sess, crate_type) {
-            bug!(
-                "invalid output type `{:?}` for target os `{}`",
-                crate_type,
-                sess.opts.target_triple
-            );
+            bug!("invalid output type `{:?}` for target `{}`", crate_type, sess.opts.target_triple);
         }
 
         sess.time("link_binary_check_files_are_writeable", || {
@@ -996,6 +992,7 @@ fn link_natively(
                         && (code < 1000 || code > 9999)
                     {
                         let is_vs_installed = windows_registry::find_vs_version().is_ok();
+                        // FIXME(cc-rs#1265) pass only target arch to find_tool()
                         let has_linker = windows_registry::find_tool(
                             sess.opts.target_triple.tuple(),
                             "link.exe",

compiler/rustc_codegen_ssa/src/back/linker.rs

@@ -47,6 +47,7 @@ pub(crate) fn get_linker<'a>(
     self_contained: bool,
     target_cpu: &'a str,
 ) -> Box<dyn Linker + 'a> {
+    // FIXME(cc-rs#1265) pass only target arch to find_tool()
     let msvc_tool = windows_registry::find_tool(sess.opts.target_triple.tuple(), "link.exe");
 
     // If our linker looks like a batch script on Windows then to execute this

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -345,6 +345,8 @@ pub struct CodegenContext<B: WriteBackendMethods> {
     pub is_pe_coff: bool,
     pub target_can_use_split_dwarf: bool,
     pub target_arch: String,
+    pub target_is_like_osx: bool,
+    pub target_is_like_aix: bool,
     pub split_debuginfo: rustc_target::spec::SplitDebuginfo,
     pub split_dwarf_kind: rustc_session::config::SplitDwarfKind,
 
@@ -1195,6 +1197,8 @@ fn start_executing_work<B: ExtraBackendMethods>(
         is_pe_coff: tcx.sess.target.is_like_windows,
         target_can_use_split_dwarf: tcx.sess.target_can_use_split_dwarf(),
         target_arch: tcx.sess.target.arch.to_string(),
+        target_is_like_osx: tcx.sess.target.is_like_osx,
+        target_is_like_aix: tcx.sess.target.is_like_aix,
         split_debuginfo: tcx.sess.split_debuginfo(),
         split_dwarf_kind: tcx.sess.opts.unstable_opts.split_dwarf_kind,
         parallel: backend.supports_parallel() && !sess.opts.unstable_opts.no_parallel_backend,