Auto merge of #125463 - GuillaumeGomez:rollup-287wx4y, r=GuillaumeGomez

Rollup of 6 pull requests

Successful merges:

 - #125263 (rust-lld: fallback to rustc's sysroot if there's no path to the linker in the target sysroot)
 - #125345 (rustc_codegen_llvm: add support for writing summary bitcode)
 - #125362 (Actually use TAIT instead of emulating it)
 - #125412 (Don't suggest adding the unexpected cfgs to the build-script it-self)
 - #125445 (Migrate `run-make/rustdoc-with-short-out-dir-option` to `rmake.rs`)
 - #125452 (Cleanup check-cfg handling in core and std)

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -3141,13 +3141,21 @@ fn add_lld_args(
 
     let self_contained_linker = self_contained_cli || self_contained_target;
     if self_contained_linker && !sess.opts.cg.link_self_contained.is_linker_disabled() {
+        let mut linker_path_exists = false;
         for path in sess.get_tools_search_paths(false) {
+            let linker_path = path.join("gcc-ld");
+            linker_path_exists |= linker_path.exists();
             cmd.arg({
                 let mut arg = OsString::from("-B");
-                arg.push(path.join("gcc-ld"));
+                arg.push(linker_path);
                 arg
             });
         }
+        if !linker_path_exists {
+            // As a sanity check, we emit an error if none of these paths exist: we want
+            // self-contained linking and have no linker.
+            sess.dcx().emit_fatal(errors::SelfContainedLinkerMissing);
+        }
     }
 
     // 2. Implement the "linker flavor" part of this feature by asking `cc` to use some kind of