Auto merge of #49051 - kennytm:rollup, r=kennytm

Rollup of 17 pull requests

- Successful merges: #48706, #48875, #48892, #48922, #48957, #48959, #48961, #48965, #49007, #49024, #49042, #49050, #48853, #48990, #49037, #49049, #48972
- Failed merges:

src/bootstrap/bin/rustc.rs

@@ -175,9 +175,6 @@ fn main() {
         if let Ok(s) = env::var("RUSTC_CODEGEN_UNITS") {
             cmd.arg("-C").arg(format!("codegen-units={}", s));
         }
-        if env::var("RUSTC_THINLTO").is_ok() {
-            cmd.arg("-Ccodegen-units=16").arg("-Zthinlto");
-        }
 
         // Emit save-analysis info.
         if env::var("RUSTC_SAVE_ANALYSIS") == Ok("api".to_string()) {

src/bootstrap/builder.rs

@@ -778,17 +778,6 @@ impl<'a> Builder<'a> {
             if cmd != "bench" {
                 cargo.arg("--release");
             }
-
-            if self.config.rust_codegen_units.is_none() &&
-               self.build.is_rust_llvm(compiler.host) &&
-               self.config.rust_thinlto {
-                cargo.env("RUSTC_THINLTO", "1");
-            } else if self.config.rust_codegen_units.is_none() {
-                // Generally, if ThinLTO has been disabled for some reason, we
-                // want to set the codegen units to 1. However, we shouldn't do
-                // this if the option was specifically set by the user.
-                cargo.env("RUSTC_CODEGEN_UNITS", "1");
-            }
         }
 
         if self.config.locked_deps {

src/bootstrap/config.rs

@@ -86,7 +86,6 @@ pub struct Config {
     // rust codegen options
     pub rust_optimize: bool,
     pub rust_codegen_units: Option<u32>,
-    pub rust_thinlto: bool,
     pub rust_debug_assertions: bool,
     pub rust_debuginfo: bool,
     pub rust_debuginfo_lines: bool,
@@ -270,7 +269,6 @@ impl Default for StringOrBool {
 struct Rust {
     optimize: Option<bool>,
     codegen_units: Option<u32>,
-    thinlto: Option<bool>,
     debug_assertions: Option<bool>,
     debuginfo: Option<bool>,
     debuginfo_lines: Option<bool>,
@@ -429,7 +427,6 @@ impl Config {
 
         // Store off these values as options because if they're not provided
         // we'll infer default values for them later
-        let mut thinlto = None;
         let mut llvm_assertions = None;
         let mut debuginfo_lines = None;
         let mut debuginfo_only_std = None;
@@ -473,7 +470,6 @@ impl Config {
             optimize = rust.optimize;
             ignore_git = rust.ignore_git;
             debug_jemalloc = rust.debug_jemalloc;
-            thinlto = rust.thinlto;
             set(&mut config.rust_optimize_tests, rust.optimize_tests);
             set(&mut config.rust_debuginfo_tests, rust.debuginfo_tests);
             set(&mut config.codegen_tests, rust.codegen_tests);
@@ -561,7 +557,6 @@ impl Config {
             "stable" | "beta" | "nightly" => true,
             _ => false,
         };
-        config.rust_thinlto = thinlto.unwrap_or(true);
         config.rust_debuginfo_lines = debuginfo_lines.unwrap_or(default);
         config.rust_debuginfo_only_std = debuginfo_only_std.unwrap_or(default);
 

src/bootstrap/configure.py

@@ -71,7 +71,6 @@ def v(*args):
 # Optimization and debugging options. These may be overridden by the release
 # channel, etc.
 o("optimize", "rust.optimize", "build optimized rust code")
-o("thinlto", "rust.thinlto", "build Rust with ThinLTO enabled")
 o("optimize-llvm", "llvm.optimize", "build optimized LLVM")
 o("llvm-assertions", "llvm.assertions", "build LLVM with assertions")
 o("debug-assertions", "rust.debug-assertions", "build with debugging assertions")

src/ci/run.sh

@@ -46,7 +46,6 @@ export RUST_RELEASE_CHANNEL=nightly
 if [ "$DEPLOY$DEPLOY_ALT" != "" ]; then
   RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --release-channel=$RUST_RELEASE_CHANNEL"
   RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --enable-llvm-static-stdcpp"
-  RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --disable-thinlto"
 
   if [ "$NO_LLVM_ASSERTIONS" = "1" ]; then
     RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --disable-llvm-assertions"

src/doc/rustdoc/src/documentation-tests.md

@@ -35,6 +35,22 @@ let x = 5;
 
 There's some subtlety though! Read on for more details.
 
+## Passing or failing a doctest
+
+Like regular unit tests, regular doctests are considered to "pass"
+if they compile and run without panicking.
+So if you want to demonstrate that some computation gives a certain result,
+the `assert!` family of macros works the same as other Rust code:
+
+```rust
+let foo = "foo";
+
+assert_eq!(foo, "foo");
+```
+
+This way, if the computation ever returns something different,
+the code panics and the doctest fails.
+
 ## Pre-processing examples
 
 In the example above, you'll note something strange: there's no `main`

src/liballoc/tests/string.rs

@@ -9,11 +9,8 @@
 // except according to those terms.
 
 use std::borrow::Cow;
-#[cfg(not(target_arch = "asmjs"))]
 use std::collections::CollectionAllocErr::*;
-#[cfg(not(target_arch = "asmjs"))]
 use std::mem::size_of;
-#[cfg(not(target_arch = "asmjs"))]
 use std::{usize, isize};
 
 pub trait IntoCow<'a, B: ?Sized> where B: ToOwned {
@@ -535,7 +532,6 @@ fn test_reserve_exact() {
     assert!(s.capacity() >= 33)
 }
 
-#[cfg(not(target_arch = "asmjs"))]
 #[test]
 fn test_try_reserve() {
 
@@ -613,7 +609,6 @@ fn test_try_reserve() {
 
 }
 
-#[cfg(not(target_arch = "asmjs"))]
 #[test]
 fn test_try_reserve_exact() {
 

src/liballoc/tests/vec.rs

@@ -10,11 +10,8 @@
 
 use std::borrow::Cow;
 use std::mem::size_of;
-use std::{usize, panic};
-#[cfg(not(target_arch = "asmjs"))]
-use std::isize;
+use std::{usize, isize, panic};
 use std::vec::{Drain, IntoIter};
-#[cfg(not(target_arch = "asmjs"))]
 use std::collections::CollectionAllocErr::*;
 
 struct DropCounter<'a> {
@@ -994,7 +991,6 @@ fn test_reserve_exact() {
     assert!(v.capacity() >= 33)
 }
 
-#[cfg(not(target_arch = "asmjs"))]
 #[test]
 fn test_try_reserve() {
 
@@ -1097,7 +1093,6 @@ fn test_try_reserve() {
 
 }
 
-#[cfg(not(target_arch = "asmjs"))]
 #[test]
 fn test_try_reserve_exact() {
 

src/liballoc/tests/vec_deque.rs

@@ -11,13 +11,9 @@
 use std::collections::VecDeque;
 use std::fmt::Debug;
 use std::collections::vec_deque::{Drain};
-#[cfg(not(target_arch = "asmjs"))]
 use std::collections::CollectionAllocErr::*;
-#[cfg(not(target_arch = "asmjs"))]
 use std::mem::size_of;
-use std::isize;
-#[cfg(not(target_arch = "asmjs"))]
-use std::usize;
+use std::{usize, isize};
 
 use self::Taggy::*;
 use self::Taggypar::*;
@@ -1053,7 +1049,6 @@ fn test_reserve_exact_2() {
     assert!(v.capacity() >= 48)
 }
 
-#[cfg(not(target_arch = "asmjs"))]
 #[test]
 fn test_try_reserve() {
 
@@ -1155,7 +1150,6 @@ fn test_try_reserve() {
 
 }
 
-#[cfg(not(target_arch = "asmjs"))]
 #[test]
 fn test_try_reserve_exact() {
 

src/libcore/iter/mod.rs

@@ -2605,7 +2605,7 @@ impl<I, U> DoubleEndedIterator for Flatten<I>
     }
 }
 
-#[stable(feature = "fused", since = "1.26.0")]
+#[unstable(feature = "iterator_flatten", issue = "48213")]
 impl<I, U> FusedIterator for Flatten<I>
     where I: FusedIterator, U: Iterator,
           I::Item: IntoIterator<IntoIter = U, Item = U::Item> {}

src/librustc/middle/entry.rs

@@ -55,7 +55,9 @@ impl<'a, 'tcx> ItemLikeVisitor<'tcx> for EntryContext<'a, 'tcx> {
     }
 }
 
-pub fn find_entry_point(session: &Session, hir_map: &hir_map::Map) {
+pub fn find_entry_point(session: &Session,
+                        hir_map: &hir_map::Map,
+                        crate_name: &str) {
     let any_exe = session.crate_types.borrow().iter().any(|ty| {
         *ty == config::CrateTypeExecutable
     });
@@ -81,7 +83,7 @@ pub fn find_entry_point(session: &Session, hir_map: &hir_map::Map) {
 
     hir_map.krate().visit_all_item_likes(&mut ctxt);
 
-    configure_main(&mut ctxt);
+    configure_main(&mut ctxt, crate_name);
 }
 
 // Beware, this is duplicated in libsyntax/entry.rs, make sure to keep
@@ -150,7 +152,7 @@ fn find_item(item: &Item, ctxt: &mut EntryContext, at_root: bool) {
     }
 }
 
-fn configure_main(this: &mut EntryContext) {
+fn configure_main(this: &mut EntryContext, crate_name: &str) {
     if this.start_fn.is_some() {
         *this.session.entry_fn.borrow_mut() = this.start_fn;
         this.session.entry_type.set(Some(config::EntryStart));
@@ -162,7 +164,8 @@ fn configure_main(this: &mut EntryContext) {
         this.session.entry_type.set(Some(config::EntryMain));
     } else {
         // No main function
-        let mut err = struct_err!(this.session, E0601, "main function not found");
+        let mut err = struct_err!(this.session, E0601,
+            "`main` function not found in crate `{}`", crate_name);
         if !this.non_main_fns.is_empty() {
             // There were some functions named 'main' though. Try to give the user a hint.
             err.note("the main function must be defined at the crate level \
@@ -175,6 +178,9 @@ fn configure_main(this: &mut EntryContext) {
             err.emit();
             this.session.abort_if_errors();
         } else {
+            if let Some(ref filename) = this.session.local_crate_source_file {
+                err.note(&format!("consider adding a `main` function to `{}`", filename.display()));
+            }
             if this.session.teach(&err.get_code().unwrap()) {
                 err.note("If you don't know the basics of Rust, you can go look to the Rust Book \
                           to get started: https://doc.rust-lang.org/book/");