Inject the `compiler_builtins` crate whenever the `core` crate is injected

src/Cargo.lock

@@ -10,6 +10,7 @@ dependencies = [
 name = "alloc"
 version = "0.0.0"
 dependencies = [
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
  "rand 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "std_unicode 0.0.0",
@@ -23,6 +24,7 @@ dependencies = [
  "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cc 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
  "libc 0.0.0",
 ]
@@ -32,6 +34,7 @@ name = "alloc_system"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
  "dlmalloc 0.0.0",
  "libc 0.0.0",
@@ -541,6 +544,7 @@ name = "dlmalloc"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
 ]
 
@@ -976,6 +980,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "libc"
 version = "0.0.0"
 dependencies = [
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
 ]
 
@@ -1254,6 +1259,7 @@ dependencies = [
 name = "panic_abort"
 version = "0.0.0"
 dependencies = [
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
  "libc 0.0.0",
 ]
@@ -1263,6 +1269,7 @@ name = "panic_unwind"
 version = "0.0.0"
 dependencies = [
  "alloc 0.0.0",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
  "libc 0.0.0",
  "unwind 0.0.0",
@@ -1401,6 +1408,7 @@ name = "profiler_builtins"
 version = "0.0.0"
 dependencies = [
  "cc 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
 ]
 
@@ -1797,6 +1805,7 @@ dependencies = [
  "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
 ]
 
@@ -1942,6 +1951,7 @@ dependencies = [
  "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
 ]
 
@@ -1991,6 +2001,7 @@ dependencies = [
  "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
 ]
 
@@ -2130,6 +2141,7 @@ dependencies = [
  "alloc_system 0.0.0",
  "build_helper 0.1.0",
  "cmake 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
 ]
 
@@ -2343,6 +2355,7 @@ dependencies = [
 name = "std_unicode"
 version = "0.0.0"
 dependencies = [
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
 ]
 
@@ -2725,6 +2738,7 @@ dependencies = [
 name = "unwind"
 version = "0.0.0"
 dependencies = [
+ "compiler_builtins 0.0.0",
  "core 0.0.0",
  "libc 0.0.0",
 ]

src/liballoc/Cargo.toml

@@ -10,6 +10,7 @@ path = "lib.rs"
 [dependencies]
 core = { path = "../libcore" }
 std_unicode = { path = "../libstd_unicode" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
 
 [dev-dependencies]
 rand = "0.4"

src/liballoc_jemalloc/Cargo.toml

@@ -16,6 +16,7 @@ alloc = { path = "../liballoc" }
 alloc_system = { path = "../liballoc_system" }
 core = { path = "../libcore" }
 libc = { path = "../rustc/libc_shim" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
 
 [build-dependencies]
 build_helper = { path = "../build_helper" }

src/liballoc_system/Cargo.toml

@@ -13,6 +13,7 @@ doc = false
 alloc = { path = "../liballoc" }
 core = { path = "../libcore" }
 libc = { path = "../rustc/libc_shim" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
 
 # See comments in the source for what this dependency is
 [target.'cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))'.dependencies]

src/libpanic_abort/Cargo.toml

@@ -12,3 +12,4 @@ doc = false
 [dependencies]
 core = { path = "../libcore" }
 libc = { path = "../rustc/libc_shim" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }

src/libpanic_unwind/Cargo.toml

@@ -14,3 +14,4 @@ alloc = { path = "../liballoc" }
 core = { path = "../libcore" }
 libc = { path = "../rustc/libc_shim" }
 unwind = { path = "../libunwind" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }

src/libprofiler_builtins/Cargo.toml

@@ -13,6 +13,7 @@ doc = false
 
 [dependencies]
 core = { path = "../libcore" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }
 
 [build-dependencies]
 cc = "1.0.1"

src/librustc_asan/Cargo.toml

@@ -17,3 +17,4 @@ cmake = "0.1.18"
 alloc = { path = "../liballoc" }
 alloc_system = { path = "../liballoc_system" }
 core = { path = "../libcore" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }

src/librustc_lsan/Cargo.toml

@@ -17,3 +17,4 @@ cmake = "0.1.18"
 alloc = { path = "../liballoc" }
 alloc_system = { path = "../liballoc_system" }
 core = { path = "../libcore" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }

src/librustc_msan/Cargo.toml

@@ -17,3 +17,4 @@ cmake = "0.1.18"
 alloc = { path = "../liballoc" }
 alloc_system = { path = "../liballoc_system" }
 core = { path = "../libcore" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }

src/librustc_tsan/Cargo.toml

@@ -17,3 +17,4 @@ cmake = "0.1.18"
 alloc = { path = "../liballoc" }
 alloc_system = { path = "../liballoc_system" }
 core = { path = "../libcore" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }

src/libstd/lib.rs

@@ -373,6 +373,7 @@ extern crate unwind;
 
 // compiler-rt intrinsics
 #[doc(masked)]
+#[cfg(stage0)]
 extern crate compiler_builtins;
 
 // During testing, this crate is not actually the "real" std library, but rather

src/libstd_unicode/Cargo.toml

@@ -15,3 +15,4 @@ path = "tests/lib.rs"
 
 [dependencies]
 core = { path = "../libcore" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }

src/libsyntax/print/pprust.rs

@@ -94,7 +94,7 @@ pub fn print_crate<'a>(cm: &'a CodeMap,
                        is_expanded: bool) -> io::Result<()> {
     let mut s = State::new_from_input(cm, sess, filename, input, out, ann, is_expanded);
 
-    if is_expanded && !std_inject::injected_crate_name().is_none() {
+    if is_expanded && std_inject::injected_crate_name().is_some() {
         // We need to print `#![no_std]` (and its feature gate) so that
         // compiling pretty-printed source won't inject libstd again.
         // However we don't want these attributes in the AST because

src/libsyntax/std_inject.rs

@@ -44,27 +44,38 @@ thread_local! {
 }
 
 pub fn maybe_inject_crates_ref(mut krate: ast::Crate, alt_std_name: Option<&str>) -> ast::Crate {
-    let name = if attr::contains_name(&krate.attrs, "no_core") {
+    // the first name in this list is the crate name of the crate with the prelude
+    let names: &[&str] = if attr::contains_name(&krate.attrs, "no_core") {
         return krate;
     } else if attr::contains_name(&krate.attrs, "no_std") {
-        "core"
+        if attr::contains_name(&krate.attrs, "compiler_builtins") {
+            &["core"]
+        } else {
+            &["core", "compiler_builtins"]
+        }
     } else {
-        "std"
+        &["std"]
     };
 
-    INJECTED_CRATE_NAME.with(|opt_name| opt_name.set(Some(name)));
+    for name in names {
+        krate.module.items.insert(0, P(ast::Item {
+            attrs: vec![attr::mk_attr_outer(DUMMY_SP,
+                                            attr::mk_attr_id(),
+                                            attr::mk_word_item(ast::Ident::from_str("macro_use")))],
+            vis: dummy_spanned(ast::VisibilityKind::Inherited),
+            node: ast::ItemKind::ExternCrate(alt_std_name.map(Symbol::intern)),
+            ident: ast::Ident::from_str(name),
+            id: ast::DUMMY_NODE_ID,
+            span: DUMMY_SP,
+            tokens: None,
+        }));
+    }
 
-    krate.module.items.insert(0, P(ast::Item {
-        attrs: vec![attr::mk_attr_outer(DUMMY_SP,
-                                        attr::mk_attr_id(),
-                                        attr::mk_word_item(ast::Ident::from_str("macro_use")))],
-        vis: dummy_spanned(ast::VisibilityKind::Inherited),
-        node: ast::ItemKind::ExternCrate(alt_std_name.map(Symbol::intern)),
-        ident: ast::Ident::from_str(name),
-        id: ast::DUMMY_NODE_ID,
-        span: DUMMY_SP,
-        tokens: None,
-    }));
+    // the crates have been injected, the assumption is that the first one is the one with
+    // the prelude.
+    let name = names[0];
+
+    INJECTED_CRATE_NAME.with(|opt_name| opt_name.set(Some(name)));
 
     let span = ignored_span(DUMMY_SP);
     krate.module.items.insert(0, P(ast::Item {

src/libunwind/Cargo.toml

@@ -14,3 +14,4 @@ doc = false
 [dependencies]
 core = { path = "../libcore" }
 libc = { path = "../rustc/libc_shim" }
+compiler_builtins = { path = "../rustc/compiler_builtins_shim" }

src/rustc/dlmalloc_shim/Cargo.toml

@@ -11,4 +11,5 @@ doc = false
 
 [dependencies]
 core = { path = "../../libcore" }
+compiler_builtins = { path = "../../rustc/compiler_builtins_shim" }
 alloc = { path = "../../liballoc" }

src/rustc/libc_shim/Cargo.toml

@@ -29,6 +29,8 @@ doc = false
 #
 # See https://github.com/rust-lang/rfcs/pull/1133.
 core = { path = "../../libcore" }
+compiler_builtins = { path = "../compiler_builtins_shim" }
+
 
 [features]
 # Certain parts of libc are conditionally compiled differently than when used