Remove get_install_prefix_lib_path completely

It was broken anyway for rustup installs and nobody seems to have noticed.

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -1569,21 +1569,12 @@ fn add_rpath_args(
     // where extern libraries might live, based on the
     // add_lib_search_paths
     if sess.opts.cg.rpath {
-        let target_triple = sess.opts.target_triple.triple();
-        let mut get_install_prefix_lib_path = || {
-            let tlib = rustc_target::target_rustlib_path(&sess.sysroot, target_triple).join("lib");
-            let mut path = PathBuf::from(&sess.sysroot);
-            path.push(&tlib);
-
-            path
-        };
         let mut rpath_config = RPathConfig {
             used_crates: &codegen_results.crate_info.used_crates_dynamic,
             out_filename: out_filename.to_path_buf(),
             has_rpath: sess.target.has_rpath,
             is_like_osx: sess.target.is_like_osx,
             linker_is_gnu: sess.target.linker_is_gnu,
-            get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
         };
         cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
     }

compiler/rustc_codegen_ssa/src/back/rpath.rs

@@ -13,7 +13,6 @@ pub struct RPathConfig<'a> {
     pub is_like_osx: bool,
     pub has_rpath: bool,
     pub linker_is_gnu: bool,
-    pub get_install_prefix_lib_path: &'a mut dyn FnMut() -> PathBuf,
 }
 
 pub fn get_rpath_flags(config: &mut RPathConfig<'_>) -> Vec<String> {
@@ -63,24 +62,13 @@ fn get_rpaths(config: &mut RPathConfig<'_>, libs: &[PathBuf]) -> Vec<String> {
     // Use relative paths to the libraries. Binaries can be moved
     // as long as they maintain the relative relationship to the
     // crates they depend on.
-    let rel_rpaths = get_rpaths_relative_to_output(config, libs);
+    let rpaths = get_rpaths_relative_to_output(config, libs);
 
-    // And a final backup rpath to the global library location.
-    let fallback_rpaths = vec![get_install_prefix_rpath(config)];
-
-    fn log_rpaths(desc: &str, rpaths: &[String]) {
-        debug!("{} rpaths:", desc);
-        for rpath in rpaths {
-            debug!("    {}", *rpath);
-        }
+    debug!("rpaths:");
+    for rpath in &rpaths {
+        debug!("    {}", rpath);
     }
 
-    log_rpaths("relative", &rel_rpaths);
-    log_rpaths("fallback", &fallback_rpaths);
-
-    let mut rpaths = rel_rpaths;
-    rpaths.extend_from_slice(&fallback_rpaths);
-
     // Remove duplicates
     minimize_rpaths(&rpaths)
 }
@@ -113,13 +101,6 @@ fn path_relative_from(path: &Path, base: &Path) -> Option<PathBuf> {
     diff_paths(path, base)
 }
 
-fn get_install_prefix_rpath(config: &mut RPathConfig<'_>) -> String {
-    let path = (config.get_install_prefix_lib_path)();
-    let path = env::current_dir().unwrap().join(&path);
-    // FIXME (#9639): This needs to handle non-utf8 paths
-    path.to_str().expect("non-utf8 component in rpath").to_owned()
-}
-
 fn minimize_rpaths(rpaths: &[String]) -> Vec<String> {
     let mut set = FxHashSet::default();
     let mut minimized = Vec::new();

compiler/rustc_codegen_ssa/src/back/rpath/tests.rs

@@ -40,15 +40,13 @@ fn test_rpath_relative() {
             is_like_osx: true,
             linker_is_gnu: false,
             out_filename: PathBuf::from("bin/rustc"),
-            get_install_prefix_lib_path: &mut || panic!(),
         };
         let res = get_rpath_relative_to_output(config, Path::new("lib/libstd.so"));
         assert_eq!(res, "@loader_path/../lib");
     } else {
         let config = &mut RPathConfig {
             used_crates: &[],
             out_filename: PathBuf::from("bin/rustc"),
-            get_install_prefix_lib_path: &mut || panic!(),
             has_rpath: true,
             is_like_osx: false,
             linker_is_gnu: true,