[beta] another round of backports for 1.42

Cargo.lock

@@ -575,9 +575,9 @@ dependencies = [
 
 [[package]]
 name = "compiler_builtins"
-version = "0.1.24"
+version = "0.1.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b9975aefa63997ef75ca9cf013ff1bb81487aaa0b622c21053afd3b92979a7af"
+checksum = "438ac08ddc5efe81452f984a9e33ba425b00b31d1f48e6acd9e2210aa28cc52e"
 dependencies = [
  "cc",
  "rustc-std-workspace-core",

RELEASES.md

@@ -1,3 +1,100 @@
+Version 1.42.0 (2020-03-12)
+==========================
+
+Language
+--------
+- [You can now use the slice pattern syntax with subslices.][67712] e.g.
+  ```rust
+  fn foo(words: &[&str]) {
+      match words {
+          ["Hello", "World", "!", ..] => println!("Hello World!"),
+          ["Foo", "Bar", ..] => println!("Baz"),
+          rest => println!("{:?}", rest),
+      }
+  }
+  ```
+- [You can now use `#[repr(transparent)]` on univariant `enum`s.][68122] Meaning
+  that you can create an enum that has the exact layout and ABI of the type
+  it contains.
+- [There are some *syntax-only* changes:][67131]
+   - `default` is syntactically allowed before items in `trait` definitions.
+   - Items in `impl`s (i.e. `const`s, `type`s, and `fn`s) may syntactically
+     leave out their bodies in favor of `;`.
+   - Bounds on associated types in `impl`s are now syntactically allowed
+     (e.g. `type Foo: Ord;`).
+   - `...` (the C-variadic type) may occur syntactically directly as the type of
+      any function parameter.
+
+  These are still rejected *semantically*, so you will likely receive an error
+  but these changes can be seen and parsed by procedural macros and
+  conditional compilation.
+
+Compiler
+--------
+- [Added tier 2\* support for `armv7a-none-eabi`.][68253]
+- [Added tier 2 support for `riscv64gc-unknown-linux-gnu`.][68339]
+- [`Option::{expect,unwrap}` and
+   `Result::{expect, expect_err, unwrap, unwrap_err}` now produce panic messages
+   pointing to the location where they were called, rather than
+   `core`'s internals. ][67887]
+
+\* Refer to Rust's [platform support page][forge-platform-support] for more
+information on Rust's tiered platform support.
+
+Libraries
+---------
+- [`iter::Empty<T>` now implements `Send` and `Sync` for any `T`.][68348]
+- [`Pin::{map_unchecked, map_unchecked_mut}` no longer require the return type
+   to implement `Sized`.][67935]
+- [`io::Cursor` now derives `PartialEq` and `Eq`.][67233]
+- [`Layout::new` is now `const`.][66254]
+- [Added Standard Library support for `riscv64gc-unknown-linux-gnu`.][66899]
+
+
+Stabilized APIs
+---------------
+- [`CondVar::wait_while`]
+- [`CondVar::wait_timeout_while`]
+- [`DebugMap::key`]
+- [`DebugMap::value`]
+- [`ManuallyDrop::take`]
+- [`matches!`]
+- [`ptr::slice_from_raw_parts_mut`]
+- [`ptr::slice_from_raw_parts`]
+
+Cargo
+-----
+- [You no longer need to include `extern crate proc_macro;` to be able to
+  `use proc_macro;` in the `2018` edition.][cargo/7700]
+
+Compatibility Notes
+-------------------
+- [`Error::description` has been deprecated, and its use will now produce a
+  warning.][66919] It's recommended to use `Display`/`to_string` instead.
+
+[68253]: https://github.com/rust-lang/rust/pull/68253/
+[68348]: https://github.com/rust-lang/rust/pull/68348/
+[67935]: https://github.com/rust-lang/rust/pull/67935/
+[68339]: https://github.com/rust-lang/rust/pull/68339/
+[68122]: https://github.com/rust-lang/rust/pull/68122/
+[67712]: https://github.com/rust-lang/rust/pull/67712/
+[67887]: https://github.com/rust-lang/rust/pull/67887/
+[67131]: https://github.com/rust-lang/rust/pull/67131/
+[67233]: https://github.com/rust-lang/rust/pull/67233/
+[66899]: https://github.com/rust-lang/rust/pull/66899/
+[66919]: https://github.com/rust-lang/rust/pull/66919/
+[66254]: https://github.com/rust-lang/rust/pull/66254/
+[cargo/7700]: https://github.com/rust-lang/cargo/pull/7700
+[`DebugMap::key`]: https://doc.rust-lang.org/stable/std/fmt/struct.DebugMap.html#method.key
+[`DebugMap::value`]: https://doc.rust-lang.org/stable/std/fmt/struct.DebugMap.html#method.value
+[`ManuallyDrop::take`]: https://doc.rust-lang.org/stable/std/mem/struct.ManuallyDrop.html#method.take
+[`matches!`]: https://doc.rust-lang.org/stable/std/macro.matches.html
+[`ptr::slice_from_raw_parts_mut`]: https://doc.rust-lang.org/stable/std/ptr/fn.slice_from_raw_parts_mut.html
+[`ptr::slice_from_raw_parts`]: https://doc.rust-lang.org/stable/std/ptr/fn.slice_from_raw_parts.html
+[`CondVar::wait_while`]: https://doc.rust-lang.org/stable/std/sync/struct.Condvar.html#method.wait_while
+[`CondVar::wait_timeout_while`]: https://doc.rust-lang.org/stable/std/sync/struct.Condvar.html#method.wait_timeout_while
+
+
 Version 1.41.1 (2020-02-27)
 ===========================
 
@@ -8,6 +105,7 @@ Version 1.41.1 (2020-02-27)
 [69225]: https://github.com/rust-lang/rust/issues/69225
 [69145]: https://github.com/rust-lang/rust/pull/69145
 
+
 Version 1.41.0 (2020-01-30)
 ===========================
 

src/librustc_errors/diagnostic_builder.rs

@@ -132,12 +132,11 @@ impl<'a> DiagnosticBuilder<'a> {
 
         let handler = self.0.handler;
 
-        // We need to use `ptr::read` because `DiagnosticBuilder` implements `Drop`.
-        let diagnostic;
-        unsafe {
-            diagnostic = std::ptr::read(&self.0.diagnostic);
-            std::mem::forget(self);
-        };
+        // We must use `Level::Cancelled` for `dummy` to avoid an ICE about an
+        // unused diagnostic.
+        let dummy = Diagnostic::new(Level::Cancelled, "");
+        let diagnostic = std::mem::replace(&mut self.0.diagnostic, dummy);
+
         // Logging here is useful to help track down where in logs an error was
         // actually emitted.
         debug!("buffer: diagnostic={:?}", diagnostic);

src/librustc_errors/lib.rs

@@ -446,22 +446,12 @@ impl Handler {
     }
 
     /// Stash a given diagnostic with the given `Span` and `StashKey` as the key for later stealing.
-    /// If the diagnostic with this `(span, key)` already exists, this will result in an ICE.
     pub fn stash_diagnostic(&self, span: Span, key: StashKey, diag: Diagnostic) {
         let mut inner = self.inner.borrow_mut();
-        if let Some(mut old_diag) = inner.stashed_diagnostics.insert((span, key), diag) {
-            // We are removing a previously stashed diagnostic which should not happen.
-            old_diag.level = Bug;
-            old_diag.note(&format!(
-                "{}:{}: already existing stashed diagnostic with (span = {:?}, key = {:?})",
-                file!(),
-                line!(),
-                span,
-                key
-            ));
-            inner.emit_diag_at_span(old_diag, span);
-            panic!(ExplicitBug);
-        }
+        // FIXME(Centril, #69537): Consider reintroducing panic on overwriting a stashed diagnostic
+        // if/when we have a more robust macro-friendly replacement for `(span, key)` as a key.
+        // See the PR for a discussion.
+        inner.stashed_diagnostics.insert((span, key), diag);
     }
 
     /// Steal a previously stashed diagnostic with the given `Span` and `StashKey` as the key.

src/librustc_typeck/check/expr.rs

@@ -1311,6 +1311,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         ty_span: Span,
     ) {
         if variant.recovered {
+            self.set_tainted_by_errors();
             return;
         }
         let mut err = self.type_error_struct_with_diag(

src/librustc_typeck/collect.rs

@@ -316,7 +316,7 @@ impl AstConv<'tcx> for ItemCtxt<'tcx> {
     }
 
     fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
-        self.tcx().sess.delay_span_bug(span, "bad placeholder type");
+        placeholder_type_error(self.tcx(), span, &[], vec![span], false);
         self.tcx().types.err
     }
 

src/test/run-make-fulldeps/issue-68794-textrel-on-minimal-lib/Makefile

@@ -0,0 +1,17 @@
+# Regression test for issue #68794
+#
+# Verify that no text relocations are accidentally introduced by linking a
+# minimal rust staticlib.
+#
+# The test links a rust static library into a shared library, and checks that
+# the linker doesn't have to flag the resulting file as containing TEXTRELs.
+
+-include ../tools.mk
+
+# only-linux
+
+all:
+	$(RUSTC) foo.rs
+	$(CC) bar.c $(call STATICLIB,foo) -fPIC -shared -o $(call DYLIB,bar) \
+		$(EXTRACFLAGS) $(EXTRACXXFLAGS)
+	readelf -d $(call DYLIB,bar) | grep TEXTREL; test $$? -eq 1

src/test/run-make-fulldeps/issue-68794-textrel-on-minimal-lib/bar.c

@@ -0,0 +1,6 @@
+void foo();
+
+int main() {
+    foo();
+    return 0;
+}

src/test/run-make-fulldeps/issue-68794-textrel-on-minimal-lib/foo.rs

@@ -0,0 +1,8 @@
+#![crate_type = "staticlib"]
+
+#[no_mangle]
+pub extern "C" fn foo(x: u32) {
+    // using the println! makes it so that enough code from the standard
+    // library is included (see issue #68794)
+    println!("foo: {}", x);
+}

src/test/ui/did_you_mean/bad-assoc-ty.rs

@@ -17,6 +17,7 @@ type D = (u8, u8)::AssocTy;
 type E = _::AssocTy;
 //~^ ERROR missing angle brackets in associated item path
 //~| ERROR the type placeholder `_` is not allowed within types on item signatures
+//~| ERROR the type placeholder `_` is not allowed within types on item signatures
 
 type F = &'static (u8)::AssocTy;
 //~^ ERROR missing angle brackets in associated item path

src/test/ui/did_you_mean/bad-assoc-ty.stderr

@@ -29,25 +29,25 @@ LL | type E = _::AssocTy;
    |          ^^^^^^^^^^ help: try: `<_>::AssocTy`
 
 error: missing angle brackets in associated item path
-  --> $DIR/bad-assoc-ty.rs:21:19
+  --> $DIR/bad-assoc-ty.rs:22:19
    |
 LL | type F = &'static (u8)::AssocTy;
    |                   ^^^^^^^^^^^^^ help: try: `<(u8)>::AssocTy`
 
 error: missing angle brackets in associated item path
-  --> $DIR/bad-assoc-ty.rs:27:10
+  --> $DIR/bad-assoc-ty.rs:28:10
    |
 LL | type G = dyn 'static + (Send)::AssocTy;
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `<dyn 'static + (Send)>::AssocTy`
 
 error: missing angle brackets in associated item path
-  --> $DIR/bad-assoc-ty.rs:44:10
+  --> $DIR/bad-assoc-ty.rs:45:10
    |
 LL | type I = ty!()::AssocTy;
    |          ^^^^^^^^^^^^^^ help: try: `<ty!()>::AssocTy`
 
 error: missing angle brackets in associated item path
-  --> $DIR/bad-assoc-ty.rs:37:19
+  --> $DIR/bad-assoc-ty.rs:38:19
    |
 LL |     ($ty: ty) => ($ty::AssocTy);
    |                   ^^^^^^^^^^^^ help: try: `<$ty>::AssocTy`
@@ -85,26 +85,32 @@ error[E0121]: the type placeholder `_` is not allowed within types on item signa
 LL | type E = _::AssocTy;
    |          ^ not allowed in type signatures
 
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/bad-assoc-ty.rs:17:10
+   |
+LL | type E = _::AssocTy;
+   |          ^ not allowed in type signatures
+
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:21:19
+  --> $DIR/bad-assoc-ty.rs:22:19
    |
 LL | type F = &'static (u8)::AssocTy;
    |                   ^^^^^^^^^^^^^ help: use fully-qualified syntax: `<u8 as Trait>::AssocTy`
 
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:27:10
+  --> $DIR/bad-assoc-ty.rs:28:10
    |
 LL | type G = dyn 'static + (Send)::AssocTy;
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<(dyn std::marker::Send + 'static) as Trait>::AssocTy`
 
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:33:10
+  --> $DIR/bad-assoc-ty.rs:34:10
    |
 LL | type H = Fn(u8) -> (u8)::Output;
    |          ^^^^^^^^^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<(dyn std::ops::Fn(u8) -> u8 + 'static) as Trait>::Output`
 
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:37:19
+  --> $DIR/bad-assoc-ty.rs:38:19
    |
 LL |     ($ty: ty) => ($ty::AssocTy);
    |                   ^^^^^^^^^^^^ help: use fully-qualified syntax: `<u8 as Trait>::AssocTy`
@@ -113,12 +119,12 @@ LL | type J = ty!(u8);
    |          ------- in this macro invocation
 
 error[E0223]: ambiguous associated type
-  --> $DIR/bad-assoc-ty.rs:44:10
+  --> $DIR/bad-assoc-ty.rs:45:10
    |
 LL | type I = ty!()::AssocTy;
    |          ^^^^^^^^^^^^^^ help: use fully-qualified syntax: `<u8 as Trait>::AssocTy`
 
-error: aborting due to 19 previous errors
+error: aborting due to 20 previous errors
 
 Some errors have detailed explanations: E0121, E0223.
 For more information about an error, try `rustc --explain E0121`.

src/test/ui/issues/issue-69396-const-no-type-in-macro.rs

@@ -0,0 +1,17 @@
+macro_rules! suite {
+    ( $( $fn:ident; )* ) => {
+        $(
+            const A = "A".$fn();
+            //~^ ERROR the name `A` is defined multiple times
+            //~| ERROR missing type for `const` item
+            //~| ERROR the type placeholder `_` is not allowed within types
+        )*
+    }
+}
+
+suite! {
+    len;
+    is_empty;
+}
+
+fn main() {}

src/test/ui/issues/issue-69396-const-no-type-in-macro.stderr

@@ -0,0 +1,48 @@
+error[E0428]: the name `A` is defined multiple times
+  --> $DIR/issue-69396-const-no-type-in-macro.rs:4:13
+   |
+LL |               const A = "A".$fn();
+   |               ^^^^^^^^^^^^^^^^^^^^
+   |               |
+   |               `A` redefined here
+   |               previous definition of the value `A` here
+...
+LL | / suite! {
+LL | |     len;
+LL | |     is_empty;
+LL | | }
+   | |_- in this macro invocation
+   |
+   = note: `A` must be defined only once in the value namespace of this module
+
+error: missing type for `const` item
+  --> $DIR/issue-69396-const-no-type-in-macro.rs:4:19
+   |
+LL |               const A = "A".$fn();
+   |                     ^ help: provide a type for the item: `A: usize`
+...
+LL | / suite! {
+LL | |     len;
+LL | |     is_empty;
+LL | | }
+   | |_- in this macro invocation
+
+error[E0121]: the type placeholder `_` is not allowed within types on item signatures
+  --> $DIR/issue-69396-const-no-type-in-macro.rs:4:19
+   |
+LL |               const A = "A".$fn();
+   |                     ^
+   |                     |
+   |                     not allowed in type signatures
+   |                     help: replace `_` with the correct type: `bool`
+...
+LL | / suite! {
+LL | |     len;
+LL | |     is_empty;
+LL | | }
+   | |_- in this macro invocation
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0121, E0428.
+For more information about an error, try `rustc --explain E0121`.

src/test/ui/self/self-infer.rs

@@ -2,7 +2,9 @@ struct S;
 
 impl S {
     fn f(self: _) {} //~ERROR the type placeholder `_` is not allowed within types on item sig
+    //~^ ERROR the type placeholder `_` is not allowed within types on item sig
     fn g(self: &_) {} //~ERROR the type placeholder `_` is not allowed within types on item sig
+    //~^ ERROR the type placeholder `_` is not allowed within types on item sig
 }
 
 fn main() {}