Rollup of 20 pull requests

src/bootstrap/bin/rustc.rs

@@ -94,6 +94,10 @@ fn main() {
             cmd.arg("-Cprefer-dynamic");
         }
 
+        if env::var_os("RUSTC_PASS_RUSTBUILD_FLAG").is_some() {
+            cmd.arg("--cfg").arg("rustbuild");
+        }
+
         // Help the libc crate compile by assisting it in finding the MUSL
         // native libraries.
         if let Some(s) = env::var_os("MUSL_ROOT") {

src/bootstrap/clean.rs

@@ -22,9 +22,9 @@ use std::path::Path;
 use Build;
 
 pub fn clean(build: &Build) {
-    rm_rf(build, "tmp".as_ref());
-    rm_rf(build, &build.out.join("tmp"));
-    rm_rf(build, &build.out.join("dist"));
+    rm_rf("tmp".as_ref());
+    rm_rf(&build.out.join("tmp"));
+    rm_rf(&build.out.join("dist"));
 
     for host in build.config.host.iter() {
         let entries = match build.out.join(host).read_dir() {
@@ -38,12 +38,12 @@ pub fn clean(build: &Build) {
                 continue
             }
             let path = t!(entry.path().canonicalize());
-            rm_rf(build, &path);
+            rm_rf(&path);
         }
     }
 }
 
-fn rm_rf(build: &Build, path: &Path) {
+fn rm_rf(path: &Path) {
     if !path.exists() {
         return
     }
@@ -55,7 +55,7 @@ fn rm_rf(build: &Build, path: &Path) {
         let file = t!(file).path();
 
         if file.is_dir() {
-            rm_rf(build, &file);
+            rm_rf(&file);
         } else {
             // On windows we can't remove a readonly file, and git will
             // often clone files as readonly. As a result, we have some

src/bootstrap/lib.rs

@@ -499,6 +499,19 @@ impl Build {
                  .env("RUSTC_SNAPSHOT_LIBDIR", self.rustc_libdir(compiler));
         }
 
+        // Most of the time we want to pass `--cfg rustbuild` which will flag
+        // upstream crates.io crates to compile themselves as unstable as we're
+        // going to put them in the sysroot. If we're compiling tools, however,
+        // we don't want to do that as the upstream crates.io deps may be in the
+        // crate graph and we don't want to compile them with their unstable
+        // versions.
+        match mode {
+            Mode::Tool => {}
+            _ => {
+                cargo.env("RUSTC_PASS_RUSTBUILD_FLAG", "1");
+            }
+        }
+
         // Ignore incremental modes except for stage0, since we're
         // not guaranteeing correctness acros builds if the compiler
         // is changing under your feet.`

src/doc/unstable-book/src/SUMMARY.md

@@ -71,6 +71,7 @@
 - [repr_simd](repr-simd.md)
 - [rustc_attrs](rustc-attrs.md)
 - [rustc_diagnostic_macros](rustc-diagnostic-macros.md)
+- [rvalue_static_promotion](rvalue-static-promotion.md)
 - [sanitizer_runtime](sanitizer-runtime.md)
 - [simd](simd.md)
 - [simd_ffi](simd-ffi.md)

src/doc/unstable-book/src/allocator.md

@@ -51,6 +51,11 @@ pub extern fn __rust_allocate(size: usize, _align: usize) -> *mut u8 {
     unsafe { libc::malloc(size as libc::size_t) as *mut u8 }
 }
 
+#[no_mangle]
+pub extern fn __rust_allocate_zeroed(size: usize, _align: usize) -> *mut u8 {
+    unsafe { libc::calloc(size as libc::size_t, 1) as *mut u8 }
+}
+
 #[no_mangle]
 pub extern fn __rust_deallocate(ptr: *mut u8, _old_size: usize, _align: usize) {
     unsafe { libc::free(ptr as *mut libc::c_void) }

src/doc/unstable-book/src/rvalue-static-promotion.md

@@ -0,0 +1,23 @@
+# `rvalue_static_promotion`
+
+The tracking issue for this feature is: [#38865]
+
+[#38865]: https://github.com/rust-lang/rust/issues/38865
+
+------------------------
+
+The `rvalue_static_promotion` feature allows directly creating `'static` references to
+constant `rvalue`s, which in particular allowing for more concise code in the common case
+in which a `'static` reference is all that's needed.
+
+
+## Examples
+
+```rust
+#![feature(rvalue_static_promotion)]
+
+fn main() {
+    let DEFAULT_VALUE: &'static u32 = &42;
+    assert_eq!(*DEFAULT_VALUE, 42);
+}
+```