Auto merge of #41847 - alexcrichton:less-unstable-annotations, r=eddyb

rustc: Add a new `-Z force-unstable-if-unmarked` flag

This commit adds a new `-Z` flag to the compiler for use when bootstrapping the
compiler itself. We want to be able to use crates.io crates, but we also want
the usage of such crates to be as ergonomic as possible! To that end compiler
crates are a little tricky in that the crates.io crates are not annotated as
unstable, nor do they expect to pull in unstable dependencies.

To cover all these situations it's intended that the compiler will forever now
bootstrap with `-Z force-unstable-if-unmarked`. This flags serves a dual purpose
of forcing crates.io crates to themselves be unstable while also allowing them
to use other "unstable" crates.io crates. This should mean that adding a
dependency to compiler no longer requires upstream modification with
unstable/staged_api attributes for inclusion!

Author: bors

src/bootstrap/bin/rustc.rs

@@ -194,6 +194,8 @@ fn main() {
                 // do that we pass a weird flag to the compiler to get it to do
                 // so. Note that this is definitely a hack, and we should likely
                 // flesh out rpath support more fully in the future.
+                //
+                // FIXME: remove condition after next stage0
                 if stage != "0" {
                     cmd.arg("-Z").arg("osx-rpath-install-name");
                 }
@@ -218,6 +220,17 @@ fn main() {
             cmd.arg("-Z").arg("unstable-options");
             cmd.arg("-C").arg("target-feature=+crt-static");
         }
+
+        // Force all crates compiled by this compiler to (a) be unstable and (b)
+        // allow the `rustc_private` feature to link to other unstable crates
+        // also in the sysroot.
+        //
+        // FIXME: remove condition after next stage0
+        if env::var_os("RUSTC_FORCE_UNSTABLE").is_some() {
+            if stage != "0" {
+                cmd.arg("-Z").arg("force-unstable-if-unmarked");
+            }
+        }
     }
 
     if verbose > 1 {

src/bootstrap/lib.rs

@@ -479,7 +479,8 @@ impl Build {
         // compiled with debuginfo.
         if mode != Mode::Tool {
              cargo.env("RUSTC_DEBUGINFO", self.config.rust_debuginfo.to_string())
-                  .env("RUSTC_DEBUGINFO_LINES", self.config.rust_debuginfo_lines.to_string());
+                  .env("RUSTC_DEBUGINFO_LINES", self.config.rust_debuginfo_lines.to_string())
+                  .env("RUSTC_FORCE_UNSTABLE", "1");
         }
 
         // Enable usage of unstable features
@@ -524,7 +525,9 @@ impl Build {
         // the comipiler, libs, and tests are stable and we don't want to make
         // their deps unstable (since this would break the first invariant
         // above).
-        if mode != Mode::Tool {
+        //
+        // FIXME: remove this after next stage0
+        if mode != Mode::Tool && stage == 0 {
             cargo.env("RUSTBUILD_UNSTABLE", "1");
         }
 

src/libarena/lib.rs

@@ -19,7 +19,7 @@
 //! objects of a single type.
 
 #![crate_name = "arena"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -32,7 +32,7 @@
 #![feature(core_intrinsics)]
 #![feature(dropck_eyepatch)]
 #![feature(generic_param_attrs)]
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![cfg_attr(test, feature(test))]
 
 #![allow(deprecated)]

src/libflate/lib.rs

@@ -15,7 +15,7 @@
 //! [mz]: https://code.google.com/p/miniz/
 
 #![crate_name = "flate"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -25,7 +25,7 @@
 #![deny(warnings)]
 
 #![feature(libc)]
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![feature(unique)]
 #![cfg_attr(test, feature(rand))]
 

src/libfmt_macros/lib.rs

@@ -15,7 +15,7 @@
 //! generated instead.
 
 #![crate_name = "fmt_macros"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -25,7 +25,7 @@
        test(attr(deny(warnings))))]
 #![deny(warnings)]
 
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![feature(unicode)]
 
 pub use self::Piece::*;

src/libgetopts/lib.rs

@@ -78,9 +78,9 @@
 //! ```
 
 #![crate_name = "getopts"]
-#![unstable(feature = "rustc_private",
+#![cfg_attr(stage0, unstable(feature = "rustc_private",
             reason = "use the crates.io `getopts` library instead",
-            issue = "27812")]
+            issue = "27812"))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -91,7 +91,7 @@
 
 #![deny(missing_docs)]
 #![deny(warnings)]
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 
 use self::Name::*;
 use self::HasArg::*;

src/libgraphviz/lib.rs

@@ -284,8 +284,8 @@
 //! * [DOT language](http://www.graphviz.org/doc/info/lang.html)
 
 #![crate_name = "graphviz"]
-#![unstable(feature = "rustc_private", issue = "27812")]
-#![feature(staged_api)]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(staged_api))]
 #![crate_type = "rlib"]
 #![crate_type = "dylib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",

src/libproc_macro_plugin/lib.rs

@@ -72,7 +72,7 @@
 //! }
 //! ```
 #![crate_name = "proc_macro_plugin"]
-#![unstable(feature = "rustc_private", issue = "27812")]
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
 #![feature(plugin_registrar)]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
@@ -81,9 +81,9 @@
        html_root_url = "https://doc.rust-lang.org/nightly/")]
 #![deny(warnings)]
 
-#![feature(staged_api)]
+#![cfg_attr(stage0, feature(staged_api))]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
+#![cfg_attr(stage0, feature(rustc_private))]
 
 extern crate rustc_plugin;
 extern crate syntax;

src/librustc/lib.rs

@@ -15,7 +15,6 @@
 //! This API is completely unstable and subject to change.
 
 #![crate_name = "rustc"]
-#![unstable(feature = "rustc_private", issue = "27812")]
 #![crate_type = "dylib"]
 #![crate_type = "rlib"]
 #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
@@ -36,15 +35,17 @@
 #![feature(nonzero)]
 #![feature(quote)]
 #![feature(rustc_diagnostic_macros)]
-#![feature(rustc_private)]
 #![feature(slice_patterns)]
 #![feature(specialization)]
-#![feature(staged_api)]
 #![feature(unboxed_closures)]
 #![feature(discriminant_value)]
 #![feature(sort_unstable)]
 #![feature(trace_macros)]
 
+#![cfg_attr(stage0, unstable(feature = "rustc_private", issue = "27812"))]
+#![cfg_attr(stage0, feature(rustc_private))]
+#![cfg_attr(stage0, feature(staged_api))]
+
 #![recursion_limit="128"]
 
 extern crate arena;

src/librustc/middle/cstore.rs

@@ -233,7 +233,6 @@ pub trait CrateStore {
     fn export_macros(&self, cnum: CrateNum);
     fn lang_items(&self, cnum: CrateNum) -> Vec<(DefIndex, usize)>;
     fn missing_lang_items(&self, cnum: CrateNum) -> Vec<lang_items::LangItem>;
-    fn is_staged_api(&self, cnum: CrateNum) -> bool;
     fn is_allocator(&self, cnum: CrateNum) -> bool;
     fn is_panic_runtime(&self, cnum: CrateNum) -> bool;
     fn is_compiler_builtins(&self, cnum: CrateNum) -> bool;
@@ -356,7 +355,6 @@ impl CrateStore for DummyCrateStore {
         { bug!("lang_items") }
     fn missing_lang_items(&self, cnum: CrateNum) -> Vec<lang_items::LangItem>
         { bug!("missing_lang_items") }
-    fn is_staged_api(&self, cnum: CrateNum) -> bool { bug!("is_staged_api") }
     fn dep_kind(&self, cnum: CrateNum) -> DepKind { bug!("is_explicitly_linked") }
     fn export_macros(&self, cnum: CrateNum) { bug!("export_macros") }
     fn is_allocator(&self, cnum: CrateNum) -> bool { bug!("is_allocator") }