Auto merge of #77606 - JohnTitor:rollup-7rgahdt, r=JohnTitor

Rollup of 13 pull requests

Successful merges:

 - #76388 (Add a note about the panic behavior of math operations on time objects)
 - #76855 (Revamp rustdoc docs about documentation using `cfg`)
 - #76995 (Reduce boilerplate with the matches! macro)
 - #77228 (Add missing examples for MaybeUninit)
 - #77528 (Avoid unchecked casts in net parser)
 - #77534 (Disallow overriding forbid in same scope)
 - #77555 (Allow anyone to set regression labels)
 - #77558 (Rename bootstrap/defaults/{config.toml.PROFILE => config.PROFILE.toml})
 - #77559 (Fix rustdoc warnings about invalid Rust syntax)
 - #77560 (Fix LitKind's byte buffer to use refcounted slice)
 - #77573 (Hint doc use convert::identity relative link)
 - #77587 (Fix span for unicode escape suggestion.)
 - #77591 (Record `expansion_that_defined` into crate metadata)

Failed merges:

r? `@ghost`

20 files changed, 195 insertions, 50 deletions

diff --git a/src/bootstrap/CHANGELOG.md b/src/bootstrap/CHANGELOG.md
index d8c704f451b..7c12642da35 100644
--- a/src/bootstrap/CHANGELOG.md
+++ b/src/bootstrap/CHANGELOG.md
@@ -7,6 +7,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Non-breaking changes since the last major version]
 
 - `x.py check` needs opt-in to check tests (--all-targets) [#77473](https://github.com/rust-lang/rust/pull/77473)
+- The default bootstrap profiles are now located at `bootstrap/defaults/config.$PROFILE.toml` (previously they were located at `bootstrap/defaults/config.toml.$PROFILE`) [#77558](https://github.com/rust-lang/rust/pull/77558)
+
 
 ## [Version 2] - 2020-09-25
 
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 5314398ce9a..6265bbaf5c2 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -574,7 +574,7 @@ impl Config {
             include_path.push("src");
             include_path.push("bootstrap");
             include_path.push("defaults");
-            include_path.push(format!("config.toml.{}", include));
+            include_path.push(format!("config.{}.toml", include));
             let included_toml = get_toml(&include_path);
             toml.merge(included_toml);
         }
diff --git a/src/bootstrap/defaults/config.toml.codegen b/src/bootstrap/defaults/config.codegen.toml
index a9505922ca7..a9505922ca7 100644
--- a/src/bootstrap/defaults/config.toml.codegen
+++ b/src/bootstrap/defaults/config.codegen.toml
diff --git a/src/bootstrap/defaults/config.toml.compiler b/src/bootstrap/defaults/config.compiler.toml
index 4772de8a2cb..4772de8a2cb 100644
--- a/src/bootstrap/defaults/config.toml.compiler
+++ b/src/bootstrap/defaults/config.compiler.toml
diff --git a/src/bootstrap/defaults/config.toml.library b/src/bootstrap/defaults/config.library.toml
index e4316f4d864..e4316f4d864 100644
--- a/src/bootstrap/defaults/config.toml.library
+++ b/src/bootstrap/defaults/config.library.toml
diff --git a/src/bootstrap/defaults/config.toml.user b/src/bootstrap/defaults/config.user.toml
index 6647061d88f..6647061d88f 100644
--- a/src/bootstrap/defaults/config.toml.user
+++ b/src/bootstrap/defaults/config.user.toml
diff --git a/src/bootstrap/setup.rs b/src/bootstrap/setup.rs
index 9d3a889aa00..8a77641fbfe 100644
--- a/src/bootstrap/setup.rs
+++ b/src/bootstrap/setup.rs
@@ -20,7 +20,7 @@ pub fn setup(src_path: &Path, include_name: &str) {
             file.display()
         );
         println!(
-            "note: this will use the configuration in {}/src/bootstrap/defaults/config.toml.{}",
+            "note: this will use the configuration in {}/src/bootstrap/defaults/config.{}.toml",
             src_path.display(),
             include_name
         );
@@ -36,7 +36,7 @@ pub fn setup(src_path: &Path, include_name: &str) {
     t!(fs::write(path, settings));
 
     let include_path =
-        format!("{}/src/bootstrap/defaults/config.toml.{}", src_path.display(), include_name);
+        format!("{}/src/bootstrap/defaults/config.{}.toml", src_path.display(), include_name);
     println!("`x.py` will now use the configuration at {}", include_path);
 
     let suggestions = match include_name {
diff --git a/src/doc/rustdoc/src/advanced-features.md b/src/doc/rustdoc/src/advanced-features.md
index 8c7926f116b..8be9489c617 100644
--- a/src/doc/rustdoc/src/advanced-features.md
+++ b/src/doc/rustdoc/src/advanced-features.md
@@ -2,7 +2,7 @@
 
 The features listed on this page fall outside the rest of the main categories.
 
-## `#[cfg(doc)]`: Documenting platform-/feature-specific information
+## `#[cfg(doc)]`: Documenting platform-specific or feature-specific information
 
 For conditional compilation, Rustdoc treats your crate the same way the compiler does. Only things
 from the host target are available (or from the given `--target` if present), and everything else is
@@ -17,7 +17,7 @@ with other `#[cfg]` filters on it, you can write something like `#[cfg(any(windo
 This will preserve the item either when built normally on Windows, or when being documented
 anywhere.
 
-Please note that this feature is not passed to doctests.
+Please note that this `cfg` is not passed to doctests.
 
 Example:
 
@@ -33,6 +33,40 @@ pub struct UnixToken;
 Here, the respective tokens can only be used by dependent crates on their respective platforms, but
 they will both appear in documentation.
 
+### Interactions between platform-specific docs
+
+Rustdoc does not have a magic way to compile documentation 'as-if' you'd run it once for each
+platform (such a magic wand has been called the ['holy grail of rustdoc'][#1998]). Instead,
+it sees *all* of your code at once, the same way the Rust compiler would if you passed it
+`--cfg doc`. However, Rustdoc has a trick up its sleeve to handle platform-specific code if it
+*does* receive it.
+
+To document your crate, Rustdoc only needs to know the public signature of your functions.
+In particular, it doesn't have to know how any of your functions are implemented, so it ignores
+all type errors and name resolution errors with function bodies. Note that this does *not*
+work for anything outside a function body: since Rustdoc documents your types, it has to
+know what those types are! For example, this code will work regardless of the platform:
+
+<!-- `ignore` because doc-tests are run with `rustc`, not `rustdoc` -->
+```ignore
+pub fn f() {
+    use std::os::windows::ffi::OsStrExt;
+}
+```
+
+but this will not, because the unknown type is part of the function signature:
+
+```ignore
+pub fn f() -> std::os::windows::ffi::EncodeWide<'static> {
+    unimplemented!()
+}
+```
+
+For a more realistic example of code this allows, see [the rustdoc test suite][realistic-async].
+
+[#1998]: https://github.com/rust-lang/rust/issues/1998
+[realistic-async]: https://github.com/rust-lang/rust/blob/b146000e910ccd60bdcde89363cb6aa14ecc0d95/src/test/rustdoc-ui/error-in-impl-trait/realistic-async.rs
+
 ## Add aliases for an item in documentation search
 
 This feature allows you to add alias(es) to an item when using the `rustdoc` search through the
diff --git a/src/doc/rustdoc/src/unstable-features.md b/src/doc/rustdoc/src/unstable-features.md
index e4d8818b56c..16157a4b080 100644
--- a/src/doc/rustdoc/src/unstable-features.md
+++ b/src/doc/rustdoc/src/unstable-features.md
@@ -43,28 +43,16 @@ plain text.
 These features operate by extending the `#[doc]` attribute, and thus can be caught by the compiler
 and enabled with a `#![feature(...)]` attribute in your crate.
 
-### Documenting platform-/feature-specific information
+### `#[doc(cfg)]`: Recording what platforms or features are required for code to be present
 
-Because of the way Rustdoc documents a crate, the documentation it creates is specific to the target
-rustc compiles for. Anything that's specific to any other target is dropped via `#[cfg]` attribute
-processing early in the compilation process. However, Rustdoc has a trick up its sleeve to handle
-platform-specific code if it *does* receive it.
+You can use `#[doc(cfg(...))]` to tell Rustdoc exactly which platform items appear on.
+This has two effects:
 
-Because Rustdoc doesn't need to fully compile a crate to binary, it replaces function bodies with
-`loop {}` to prevent having to process more than necessary. This means that any code within a
-function that requires platform-specific pieces is ignored. Combined with a special attribute,
-`#[doc(cfg(...))]`, you can tell Rustdoc exactly which platform something is supposed to run on,
-ensuring that doctests are only run on the appropriate platforms.
-
-The `#[doc(cfg(...))]` attribute has another effect: When Rustdoc renders documentation for that
-item, it will be accompanied by a banner explaining that the item is only available on certain
-platforms.
-
-For Rustdoc to document an item, it needs to see it, regardless of what platform it's currently
-running on. To aid this, Rustdoc sets the flag `#[cfg(doc)]` when running on your crate.
-Combining this with the target platform of a given item allows it to appear when building your crate
-normally on that platform, as well as when building documentation anywhere.
+1. doctests will only run on the appropriate platforms, and
+2. When Rustdoc renders documentation for that item, it will be accompanied by a banner explaining
+   that the item is only available on certain platforms.
 
+`#[doc(cfg)]` is intended to be used alongside [`#[cfg(doc)]`][cfg-doc].
 For example, `#[cfg(any(windows, doc))]` will preserve the item either on Windows or during the
 documentation process. Then, adding a new attribute `#[doc(cfg(windows))]` will tell Rustdoc that
 the item is supposed to be used on Windows. For example:
@@ -81,6 +69,12 @@ pub struct WindowsToken;
 #[cfg(any(unix, doc))]
 #[doc(cfg(unix))]
 pub struct UnixToken;
+
+/// Token struct that is only available with the `serde` feature
+#[cfg(feature = "serde")]
+#[doc(cfg(feature = "serde"))]
+#[derive(serde::Deserialize)]
+pub struct SerdeToken;
 ```
 
 In this sample, the tokens will only appear on their respective platforms, but they will both appear
@@ -90,6 +84,7 @@ in documentation.
 `#![feature(doc_cfg)]` feature gate. For more information, see [its chapter in the Unstable
 Book][unstable-doc-cfg] and [its tracking issue][issue-doc-cfg].
 
+[cfg-doc]: ./advanced-features.md
 [unstable-doc-cfg]: ../unstable-book/language-features/doc-cfg.html
 [issue-doc-cfg]: https://github.com/rust-lang/rust/issues/43781
 
diff --git a/src/test/ui/fmt/format-string-error-2.stderr b/src/test/ui/fmt/format-string-error-2.stderr
index d202044a2bb..c421fe49ef0 100644
--- a/src/test/ui/fmt/format-string-error-2.stderr
+++ b/src/test/ui/fmt/format-string-error-2.stderr
@@ -2,9 +2,7 @@ error: incorrect unicode escape sequence
   --> $DIR/format-string-error-2.rs:77:20
    |
 LL |     println!("\x7B}\u8 {", 1);
-   |                    ^^-
-   |                      |
-   |                      help: format of unicode escape sequences uses braces: `\u{8}`
+   |                    ^^^ help: format of unicode escape sequences uses braces: `\u{8}`
 
 error: invalid format string: expected `'}'`, found `'a'`
   --> $DIR/format-string-error-2.rs:5:5
diff --git a/src/test/ui/hygiene/auxiliary/def-site-async-await.rs b/src/test/ui/hygiene/auxiliary/def-site-async-await.rs
new file mode 100644
index 00000000000..f7e9b801318
--- /dev/null
+++ b/src/test/ui/hygiene/auxiliary/def-site-async-await.rs
@@ -0,0 +1,7 @@
+// edition:2018
+
+extern crate opaque_hygiene;
+
+pub async fn serve() {
+    opaque_hygiene::make_it!();
+}
diff --git a/src/test/ui/hygiene/auxiliary/opaque-hygiene.rs b/src/test/ui/hygiene/auxiliary/opaque-hygiene.rs
new file mode 100644
index 00000000000..7730f91bd6a
--- /dev/null
+++ b/src/test/ui/hygiene/auxiliary/opaque-hygiene.rs
@@ -0,0 +1,21 @@
+// force-host
+// no-prefer-dynamic
+
+#![feature(proc_macro_quote)]
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+use proc_macro::{TokenStream, quote};
+
+#[proc_macro]
+pub fn make_it(input: TokenStream) -> TokenStream {
+    // `quote!` applies def-site hygiene
+    quote! {
+        trait Foo {
+            fn my_fn(&self) {}
+        }
+
+        impl<T> Foo for T {}
+        "a".my_fn();
+    }
+}
diff --git a/src/test/ui/hygiene/issue-77523-def-site-async-await.rs b/src/test/ui/hygiene/issue-77523-def-site-async-await.rs
new file mode 100644
index 00000000000..2af60ff6f53
--- /dev/null
+++ b/src/test/ui/hygiene/issue-77523-def-site-async-await.rs
@@ -0,0 +1,19 @@
+// build-pass
+// aux-build:opaque-hygiene.rs
+// aux-build:def-site-async-await.rs
+
+// Regression test for issue #77523
+// Tests that we don't ICE when an unusual combination
+// of def-site hygiene and cross-crate monomorphization occurs.
+
+extern crate def_site_async_await;
+
+use std::future::Future;
+
+fn mk_ctxt() -> std::task::Context<'static> {
+    panic!()
+}
+
+fn main() {
+    Box::pin(def_site_async_await::serve()).as_mut().poll(&mut mk_ctxt());
+}
diff --git a/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs b/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs
new file mode 100644
index 00000000000..8e25227b59e
--- /dev/null
+++ b/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.rs
@@ -0,0 +1,49 @@
+// This test is checking that you cannot override a `forbid` by adding in other
+// attributes later in the same scope. (We already ensure that you cannot
+// override it in nested scopes).
+
+// If you turn off deduplicate diagnostics (which rustc turns on by default but
+// compiletest turns off when it runs ui tests), then the errors are
+// (unfortunately) repeated here because the checking is done as we read in the
+// errors, and curretly that happens two or three different times, depending on
+// compiler flags.
+//
+// I decided avoiding the redundant output was not worth the time in engineering
+// effort for bug like this, which 1. end users are unlikely to run into in the
+// first place, and 2. they won't see the redundant output anyway.
+
+// compile-flags: -Z deduplicate-diagnostics=yes
+
+fn forbid_first(num: i32) -> i32 {
+    #![forbid(unused)]
+    #![deny(unused)]
+    //~^ ERROR: deny(unused) incompatible with previous forbid in same scope [E0453]
+    #![warn(unused)]
+    //~^ ERROR: warn(unused) incompatible with previous forbid in same scope [E0453]
+    #![allow(unused)]
+    //~^ ERROR: allow(unused) incompatible with previous forbid in same scope [E0453]
+
+    num * num
+}
+
+fn forbid_last(num: i32) -> i32 {
+    #![deny(unused)]
+    #![warn(unused)]
+    #![allow(unused)]
+    #![forbid(unused)]
+
+    num * num
+}
+
+fn forbid_multiple(num: i32) -> i32 {
+    #![forbid(unused)]
+    #![forbid(unused)]
+
+    num * num
+}
+
+fn main() {
+    forbid_first(10);
+    forbid_last(10);
+    forbid_multiple(10);
+}
diff --git a/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.stderr b/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.stderr
new file mode 100644
index 00000000000..3951c511bf4
--- /dev/null
+++ b/src/test/ui/lint/issue-70819-dont-override-forbid-in-same-scope.stderr
@@ -0,0 +1,29 @@
+error[E0453]: deny(unused) incompatible with previous forbid in same scope
+  --> $DIR/issue-70819-dont-override-forbid-in-same-scope.rs:19:13
+   |
+LL |     #![forbid(unused)]
+   |               ------ `forbid` level set here
+LL |     #![deny(unused)]
+   |             ^^^^^^
+
+error[E0453]: warn(unused) incompatible with previous forbid in same scope
+  --> $DIR/issue-70819-dont-override-forbid-in-same-scope.rs:21:13
+   |
+LL |     #![forbid(unused)]
+   |               ------ `forbid` level set here
+...
+LL |     #![warn(unused)]
+   |             ^^^^^^
+
+error[E0453]: allow(unused) incompatible with previous forbid in same scope
+  --> $DIR/issue-70819-dont-override-forbid-in-same-scope.rs:23:14
+   |
+LL |     #![forbid(unused)]
+   |               ------ `forbid` level set here
+...
+LL |     #![allow(unused)]
+   |              ^^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0453`.
diff --git a/src/test/ui/parser/issue-23620-invalid-escapes.stderr b/src/test/ui/parser/issue-23620-invalid-escapes.stderr
index b391ac75bf8..8c924ad0330 100644
--- a/src/test/ui/parser/issue-23620-invalid-escapes.stderr
+++ b/src/test/ui/parser/issue-23620-invalid-escapes.stderr
@@ -80,9 +80,9 @@ error: incorrect unicode escape sequence
   --> $DIR/issue-23620-invalid-escapes.rs:32:14
    |
 LL |     let _ = "\u8f";
-   |              ^^--
-   |                |
-   |                help: format of unicode escape sequences uses braces: `\u{8f}`
+   |              ^^^-
+   |              |
+   |              help: format of unicode escape sequences uses braces: `\u{8f}`
 
 error: aborting due to 13 previous errors
 
diff --git a/src/test/ui/rfc-2565-param-attrs/param-attrs-allowed.rs b/src/test/ui/rfc-2565-param-attrs/param-attrs-allowed.rs
index 1217f89cb31..a547d09d048 100644
--- a/src/test/ui/rfc-2565-param-attrs/param-attrs-allowed.rs
+++ b/src/test/ui/rfc-2565-param-attrs/param-attrs-allowed.rs
@@ -8,8 +8,8 @@ extern "C" {
         #[allow(unused_mut)] a: i32,
         #[cfg(something)] b: i32,
         #[cfg_attr(something, cfg(nothing))] c: i32,
-        #[deny(unused_mut)] d: i32,
-        #[forbid(unused_mut)] #[warn(unused_mut)] ...
+        #[forbid(unused_mut)] d: i32,
+        #[deny(unused_mut)] #[warn(unused_mut)] ...
     );
 }
 
@@ -17,16 +17,16 @@ type FnType = fn(
     #[allow(unused_mut)] a: i32,
     #[cfg(something)] b: i32,
     #[cfg_attr(something, cfg(nothing))] c: i32,
-    #[deny(unused_mut)] d: i32,
-    #[forbid(unused_mut)] #[warn(unused_mut)] e: i32
+    #[forbid(unused_mut)] d: i32,
+    #[deny(unused_mut)] #[warn(unused_mut)] e: i32
 );
 
 pub fn foo(
     #[allow(unused_mut)] a: i32,
     #[cfg(something)] b: i32,
     #[cfg_attr(something, cfg(nothing))] c: i32,
-    #[deny(unused_mut)] d: i32,
-    #[forbid(unused_mut)] #[warn(unused_mut)] _e: i32
+    #[forbid(unused_mut)] d: i32,
+    #[deny(unused_mut)] #[warn(unused_mut)] _e: i32
 ) {}
 
 // self
diff --git a/src/tools/clippy/clippy_lints/src/consts.rs b/src/tools/clippy/clippy_lints/src/consts.rs
index 0000d39263e..062c9bd2d9e 100644
--- a/src/tools/clippy/clippy_lints/src/consts.rs
+++ b/src/tools/clippy/clippy_lints/src/consts.rs
@@ -155,7 +155,7 @@ pub fn lit_to_constant(lit: &LitKind, ty: Option<Ty<'_>>) -> Constant {
     match *lit {
         LitKind::Str(ref is, _) => Constant::Str(is.to_string()),
         LitKind::Byte(b) => Constant::Int(u128::from(b)),
-        LitKind::ByteStr(ref s) => Constant::Binary(Lrc::from(s.as_slice())),
+        LitKind::ByteStr(ref s) => Constant::Binary(Lrc::clone(s)),
         LitKind::Char(c) => Constant::Char(c),
         LitKind::Int(n, _) => Constant::Int(n),
         LitKind::Float(ref is, LitFloatType::Suffixed(fty)) => match fty {
diff --git a/src/tools/clippy/tests/ui/attrs.rs b/src/tools/clippy/tests/ui/attrs.rs
index 908d063729f..32685038067 100644
--- a/src/tools/clippy/tests/ui/attrs.rs
+++ b/src/tools/clippy/tests/ui/attrs.rs
@@ -3,7 +3,6 @@
 // Test that the whole restriction group is not enabled
 #![warn(clippy::restriction)]
 #![deny(clippy::restriction)]
-#![forbid(clippy::restriction)]
 #![allow(clippy::missing_docs_in_private_items, clippy::panic, clippy::unreachable)]
 
 #[inline(always)]
diff --git a/src/tools/clippy/tests/ui/attrs.stderr b/src/tools/clippy/tests/ui/attrs.stderr
index ef4b89eaa6d..4324984dd60 100644
--- a/src/tools/clippy/tests/ui/attrs.stderr
+++ b/src/tools/clippy/tests/ui/attrs.stderr
@@ -1,5 +1,5 @@
 error: you have declared `#[inline(always)]` on `test_attr_lint`. This is usually a bad idea
-  --> $DIR/attrs.rs:9:1
+  --> $DIR/attrs.rs:8:1
    |
 LL | #[inline(always)]
    | ^^^^^^^^^^^^^^^^^
@@ -7,7 +7,7 @@ LL | #[inline(always)]
    = note: `-D clippy::inline-always` implied by `-D warnings`
 
 error: the since field must contain a semver-compliant version
-  --> $DIR/attrs.rs:29:14
+  --> $DIR/attrs.rs:28:14
    |
 LL | #[deprecated(since = "forever")]
    |              ^^^^^^^^^^^^^^^^^
@@ -15,7 +15,7 @@ LL | #[deprecated(since = "forever")]
    = note: `-D clippy::deprecated-semver` implied by `-D warnings`
 
 error: the since field must contain a semver-compliant version
-  --> $DIR/attrs.rs:32:14
+  --> $DIR/attrs.rs:31:14
    |
 LL | #[deprecated(since = "1")]
    |              ^^^^^^^^^^^
@@ -37,13 +37,5 @@ LL | #![deny(clippy::restriction)]
    |
    = help: try enabling only the lints you really need
 
-error: restriction lints are not meant to be all enabled
-  --> $DIR/attrs.rs:6:11
-   |
-LL | #![forbid(clippy::restriction)]
-   |           ^^^^^^^^^^^^^^^^^^^
-   |
-   = help: try enabling only the lints you really need
-
-error: aborting due to 6 previous errors
+error: aborting due to 5 previous errors