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

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -108,6 +108,7 @@ pub struct ModuleConfig {
     pub emit_asm: bool,
     pub emit_obj: EmitObj,
     pub emit_thin_lto: bool,
+    pub emit_thin_lto_summary: bool,
     pub bc_cmdline: String,
 
     // Miscellaneous flags. These are mostly copied from command-line
@@ -232,6 +233,10 @@ impl ModuleConfig {
             ),
             emit_obj,
             emit_thin_lto: sess.opts.unstable_opts.emit_thin_lto,
+            emit_thin_lto_summary: if_regular!(
+                sess.opts.output_types.contains_key(&OutputType::ThinLinkBitcode),
+                false
+            ),
             bc_cmdline: sess.target.bitcode_llvm_cmdline.to_string(),
 
             verify_llvm_ir: sess.verify_llvm_ir(),
@@ -283,6 +288,7 @@ impl ModuleConfig {
 
     pub fn bitcode_needed(&self) -> bool {
         self.emit_bc
+            || self.emit_thin_lto_summary
             || self.emit_obj == EmitObj::Bitcode
             || self.emit_obj == EmitObj::ObjectCode(BitcodeSection::Full)
     }
@@ -630,6 +636,9 @@ fn produce_final_output_artifacts(
                 // them for making an rlib.
                 copy_if_one_unit(OutputType::Bitcode, true);
             }
+            OutputType::ThinLinkBitcode => {
+                copy_if_one_unit(OutputType::ThinLinkBitcode, false);
+            }
             OutputType::LlvmAssembly => {
                 copy_if_one_unit(OutputType::LlvmAssembly, false);
             }
@@ -883,7 +892,7 @@ fn execute_optimize_work_item<B: ExtraBackendMethods>(
     match lto_type {
         ComputedLtoType::No => finish_intra_module_work(cgcx, module, module_config),
         ComputedLtoType::Thin => {
-            let (name, thin_buffer) = B::prepare_thin(module);
+            let (name, thin_buffer) = B::prepare_thin(module, false);
             if let Some(path) = bitcode {
                 fs::write(&path, thin_buffer.data()).unwrap_or_else(|e| {
                     panic!("Error writing pre-lto-bitcode file `{}`: {}", path.display(), e);