It now completely compiles without LLVM!!!

src/Cargo.lock

@@ -1343,6 +1343,7 @@ dependencies = [
  "env_logger 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "graphviz 0.0.0",
  "log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "owning_ref 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
  "rustc_allocator 0.0.0",
  "rustc_back 0.0.0",

src/librustc_driver/Cargo.toml

@@ -12,6 +12,7 @@ crate-type = ["dylib"]
 arena = { path = "../libarena" }
 graphviz = { path = "../libgraphviz" }
 log = { version = "0.3", features = ["release_max_level_info"] }
+owning_ref = "0.3.3"
 env_logger = { version = "0.4", default-features = false }
 rustc = { path = "../librustc" }
 rustc_allocator = { path = "../librustc_allocator" }

src/librustc_driver/driver.rs

@@ -18,7 +18,9 @@ use rustc::session::CompileIncomplete;
 use rustc::session::config::{self, Input, OutputFilenames, OutputType};
 use rustc::session::search_paths::PathKind;
 use rustc::lint;
-use rustc::middle::{self, dependency_format, stability, reachable};
+use rustc::middle::{self, stability, reachable};
+#[cfg(feature="llvm")]
+use rustc::middle::dependency_format;
 use rustc::middle::privacy::AccessLevels;
 use rustc::mir::transform::{MIR_CONST, MIR_VALIDATED, MIR_OPTIMIZED, Passes};
 use rustc::ty::{self, TyCtxt, Resolutions, GlobalArenas};
@@ -71,6 +73,11 @@ pub fn compile_input(sess: &Session,
                      output: &Option<PathBuf>,
                      addl_plugins: Option<Vec<String>>,
                      control: &CompileController) -> CompileResult {
+    #[cfg(feature="llvm")]
+    use rustc_trans::back::write::OngoingCrateTranslation;
+    #[cfg(not(feature="llvm"))]
+    type OngoingCrateTranslation = ();
+
     macro_rules! controller_entry_point {
         ($point: ident, $tsess: expr, $make_state: expr, $phase_result: expr) => {{
             let state = &mut $make_state;
@@ -90,7 +97,7 @@ pub fn compile_input(sess: &Session,
     // We need nested scopes here, because the intermediate results can keep
     // large chunks of memory alive and we want to free them as soon as
     // possible to keep the peak memory usage low
-    let (outputs, trans) = {
+    let (outputs, trans): (OutputFilenames, OngoingCrateTranslation) = {
         let krate = match phase_1_parse_input(control, sess, input) {
             Ok(krate) => krate,
             Err(mut parse_error) => {
@@ -213,8 +220,6 @@ pub fn compile_input(sess: &Session,
             #[cfg(feature="llvm")]
             let trans = phase_4_translate_to_llvm(tcx, analysis, incremental_hashes_map,
                                                   &outputs);
-            #[cfg(not(feature="llvm"))]
-            let trans = { panic!("LLVM not supported by this rustc."); () };
 
             if log_enabled!(::log::LogLevel::Info) {
                 println!("Post-trans");
@@ -228,12 +233,25 @@ pub fn compile_input(sess: &Session,
                 }
             }
 
+            #[cfg(not(feature="llvm"))]
+            {
+                let _ = incremental_hashes_map;
+                sess.err(&format!("LLVM is not supported by this rustc"));
+                sess.abort_if_errors();
+                unreachable!();
+            }
+
+            #[cfg(feature="llvm")]
             Ok((outputs, trans))
         })??
     };
 
     #[cfg(not(feature="llvm"))]
-    unreachable!();
+    {
+        let _ = outputs;
+        let _ = trans;
+        unreachable!();
+    }
 
     #[cfg(feature="llvm")]
     {
@@ -505,6 +523,7 @@ impl<'a, 'tcx> CompileState<'a, 'tcx> {
         }
     }
 
+    #[cfg(feature="llvm")]
     fn state_when_compilation_done(input: &'a Input,
                                    session: &'tcx Session,
                                    out_dir: &'a Option<PathBuf>,
@@ -1145,7 +1164,12 @@ fn write_out_deps(sess: &Session, outputs: &OutputFilenames, crate_name: &str) {
         match *output_type {
             OutputType::Exe => {
                 for output in sess.crate_types.borrow().iter() {
-                    let p = ::rustc_trans_utils::link::filename_for_input(sess, *output, crate_name, outputs);
+                    let p = ::rustc_trans_utils::link::filename_for_input(
+                        sess,
+                        *output,
+                        crate_name,
+                        outputs
+                    );
                     out_filenames.push(p);
                 }
             }
@@ -1263,7 +1287,7 @@ pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<c
 
     base.into_iter()
         .filter(|crate_type| {
-            let res = !rustc_trans_utils::link::invalid_output_for_target(session, *crate_type);
+            let res = !::rustc_trans_utils::link::invalid_output_for_target(session, *crate_type);
 
             if !res {
                 session.warn(&format!("dropping unsupported crate type `{}` for target `{}`",

src/librustc_driver/lib.rs

@@ -35,6 +35,8 @@ extern crate arena;
 extern crate getopts;
 extern crate graphviz;
 extern crate env_logger;
+#[cfg(not(feature="llvm"))]
+extern crate owning_ref;
 extern crate libc;
 extern crate rustc;
 extern crate rustc_allocator;
@@ -70,8 +72,6 @@ use rustc_resolve as resolve;
 use rustc_save_analysis as save;
 use rustc_save_analysis::DumpHandler;
 #[cfg(feature="llvm")]
-use rustc_trans::back::link;
-#[cfg(feature="llvm")]
 use rustc_trans::back::write::{RELOC_MODEL_ARGS, CODE_GEN_MODEL_ARGS};
 use rustc::dep_graph::DepGraph;
 use rustc::session::{self, config, Session, build_session, CompileResult};
@@ -82,7 +82,7 @@ use rustc::session::{early_error, early_warn};
 use rustc::lint::Lint;
 use rustc::lint;
 #[cfg(not(feature="llvm"))]
-use rustc::middle::cstore::MetadataLoader;
+use rustc::middle::cstore::MetadataLoader as MetadataLoaderTrait;
 use rustc_metadata::locator;
 use rustc_metadata::cstore::CStore;
 use rustc::util::common::{time, ErrorReported};
@@ -114,6 +114,9 @@ use syntax::feature_gate::{GatedCfg, UnstableFeatures};
 use syntax::parse::{self, PResult};
 use syntax_pos::{DUMMY_SP, MultiSpan};
 
+#[cfg(not(feature="llvm"))]
+use owning_ref::{OwningRef, ErasedBoxRef};
+
 #[cfg(test)]
 pub mod test;
 
@@ -174,7 +177,7 @@ pub use NoLLvmMetadataLoader as MetadataLoader;
 pub use rustc_trans::LlvmMetadataLoader as MetadataLoader;
 
 #[cfg(not(feature="llvm"))]
-impl MetadataLoader for NoLLvmMetadataLoader {
+impl MetadataLoaderTrait for NoLLvmMetadataLoader {
     fn get_rlib_metadata(&self, _: &Target, filename: &Path) -> Result<ErasedBoxRef<[u8]>, String> {
         use std::fs::File;
         use std::io;
@@ -185,11 +188,11 @@ impl MetadataLoader for NoLLvmMetadataLoader {
 
         while let Some(entry_result) = archive.next_entry() {
             let mut entry = entry_result.map_err(|e|format!("metadata section read err: {:?}", e))?;
-            if entry.header().identifier() == METADATA_FILENAME {
+            if entry.header().identifier() == "rust.metadata.bin" {
                 let mut buf = Vec::new();
                 io::copy(&mut entry, &mut buf).unwrap();
                 let buf: OwningRef<Vec<u8>, [u8]> = OwningRef::new(buf).into();
-                return Ok(buf.erase_owner());
+                return Ok(buf.map_owner_box().erase_owner());
             }
         }
 
@@ -197,8 +200,8 @@ impl MetadataLoader for NoLLvmMetadataLoader {
     }
 
     fn get_dylib_metadata(&self,
-                          target: &Target,
+                          _target: &Target,
-                          filename: &Path)
+                          _filename: &Path)
                           -> Result<ErasedBoxRef<[u8]>, String> {
         panic!("Dylib metadata loading not supported without LLVM")
     }
@@ -207,6 +210,7 @@ impl MetadataLoader for NoLLvmMetadataLoader {
 // Parse args and run the compiler. This is the primary entry point for rustc.
 // See comments on CompilerCalls below for details about the callbacks argument.
 // The FileLoader provides a way to load files from sources other than the file system.
+#[cfg_attr(not(feature="llvm"), allow(unused_mut))]
 pub fn run_compiler<'a>(args: &[String],
                         callbacks: &mut CompilerCalls<'a>,
                         file_loader: Option<Box<FileLoader + 'static>>,
@@ -516,6 +520,7 @@ impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
         Compilation::Continue
     }
 
+    #[cfg_attr(not(feature="llvm"), allow(unused_mut))]
     fn no_input(&mut self,
                 matches: &getopts::Matches,
                 sopts: &config::Options,
@@ -743,7 +748,12 @@ impl RustcDefaultCalls {
                     }
                     let crate_types = driver::collect_crate_types(sess, attrs);
                     for &style in &crate_types {
-                        let fname = rustc_trans_utils::link::filename_for_input(sess, style, &id, &t_outputs);
+                        let fname = rustc_trans_utils::link::filename_for_input(
+                            sess,
+                            style,
+                            &id,
+                            &t_outputs
+                        );
                         println!("{}",
                                  fname.file_name()
                                       .unwrap()
@@ -792,7 +802,7 @@ impl RustcDefaultCalls {
                 }
                 PrintRequest::RelocationModels => {
                     println!("Available relocation models:");
-                    #[cfg(features="llvm")]
+                    #[cfg(feature="llvm")]
                     for &(name, _) in RELOC_MODEL_ARGS.iter() {
                         println!("    {}", name);
                     }
@@ -800,7 +810,7 @@ impl RustcDefaultCalls {
                 }
                 PrintRequest::CodeModels => {
                     println!("Available code models:");
-                    #[cfg(features="llvm")]
+                    #[cfg(feature="llvm")]
                     for &(name, _) in CODE_GEN_MODEL_ARGS.iter(){
                         println!("    {}", name);
                     }

src/librustc_trans/back/link.rs

@@ -88,7 +88,8 @@ pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
     RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
 
-pub use self::rustc_trans_utils::link::{find_crate_name, filename_for_input, default_output_for_target, invalid_output_for_target};
+pub use self::rustc_trans_utils::link::{find_crate_name, filename_for_input,
+                                        default_output_for_target, invalid_output_for_target};
 
 pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap) -> LinkMeta {
     let krate_dep_node = &DepNode::new_no_params(DepKind::Krate);