Add `-Z no-link` flag

Adds a compiler option to allow rustc compile a crate without linking.
With this flag, rustc serializes codegen_results into a .rlink file.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/librustc_codegen_llvm/lib.rs b/src/librustc_codegen_llvm/lib.rs
index a6168128c4d..70e3874035b 100644
--- a/src/librustc_codegen_llvm/lib.rs
+++ b/src/librustc_codegen_llvm/lib.rs
@@ -33,6 +33,7 @@ use rustc_codegen_ssa::CompiledModule;
 use rustc_errors::{FatalError, Handler};
 use std::any::Any;
 use std::ffi::CStr;
+use std::fs;
 use std::sync::Arc;
 use syntax::expand::allocator::AllocatorKind;
 
@@ -44,6 +45,7 @@ use rustc::ty::{self, TyCtxt};
 use rustc::util::common::ErrorReported;
 use rustc_codegen_ssa::ModuleCodegen;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
+use rustc_serialize::json;
 
 mod back {
     pub mod archive;
@@ -298,6 +300,18 @@ impl CodegenBackend for LlvmCodegenBackend {
             return Ok(());
         }
 
+        if sess.opts.debugging_opts.no_link {
+            // FIXME: use a binary format to encode the `.rlink` file
+            let rlink_data = json::encode(&codegen_results).map_err(|err| {
+                sess.fatal(&format!("failed to encode rlink: {}", err));
+            })?;
+            let rlink_file = outputs.with_extension("rlink");
+            fs::write(&rlink_file, rlink_data).map_err(|err| {
+                sess.fatal(&format!("failed to write file {}: {}", rlink_file.display(), err));
+            })?;
+            return Ok(());
+        }
+
         // Run the linker on any artifacts that resulted from the LLVM run.
         // This should produce either a finished executable or library.
         sess.time("link_crate", || {