Auto merge of #57577 - Centril:rollup, r=Centril

Rollup of 4 pull requests

Successful merges:

 - #57004 (Make `TokenStream` less recursive.)
 - #57102 (NLL: Add union justifications to conflicting borrows.)
 - #57337 (rustc: Place wasm linker args first instead of last)
 - #57549 (Add #[must_use] message to Iterator and Future)

Failed merges:

r? @ghost

src/libcore/future/future.rs

@@ -23,7 +23,7 @@ use task::{Poll, LocalWaker};
 ///
 /// When using a future, you generally won't call `poll` directly, but instead
 /// `await!` the value.
-#[must_use]
+#[must_use = "futures do nothing unless polled"]
 pub trait Future {
     /// The result of the `Future`.
     type Output;

src/libcore/iter/iterator.rs

@@ -88,7 +88,7 @@ fn _assert_is_object_safe(_: &dyn Iterator<Item=()>) {}
     message="`{Self}` is not an iterator"
 )]
 #[doc(spotlight)]
-#[must_use]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 pub trait Iterator {
     /// The type of the elements being iterated over.
     #[stable(feature = "rust1", since = "1.0.0")]

src/libcore/iter/mod.rs

@@ -243,7 +243,7 @@
 //! using it. The compiler will warn us about this kind of behavior:
 //!
 //! ```text
-//! warning: unused result that must be used: iterator adaptors are lazy and
+//! warning: unused result that must be used: iterators are lazy and
 //! do nothing unless consumed
 //! ```
 //!
@@ -404,7 +404,7 @@ impl<R: Try> LoopState<R::Ok, R> {
 /// [`rev`]: trait.Iterator.html#method.rev
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Rev<T> {
     iter: T
@@ -505,7 +505,7 @@ unsafe impl<I> TrustedLen for Rev<I>
 /// [`copied`]: trait.Iterator.html#method.copied
 /// [`Iterator`]: trait.Iterator.html
 #[unstable(feature = "iter_copied", issue = "57127")]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[derive(Clone, Debug)]
 pub struct Copied<I> {
     it: I,
@@ -605,7 +605,7 @@ unsafe impl<'a, I, T: 'a> TrustedLen for Copied<I>
 /// [`cloned`]: trait.Iterator.html#method.cloned
 /// [`Iterator`]: trait.Iterator.html
 #[stable(feature = "iter_cloned", since = "1.1.0")]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[derive(Clone, Debug)]
 pub struct Cloned<I> {
     it: I,
@@ -717,7 +717,7 @@ unsafe impl<'a, I, T: 'a> TrustedLen for Cloned<I>
 /// [`cycle`]: trait.Iterator.html#method.cycle
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Cycle<I> {
     orig: I,
@@ -757,7 +757,7 @@ impl<I> FusedIterator for Cycle<I> where I: Clone + Iterator {}
 ///
 /// [`step_by`]: trait.Iterator.html#method.step_by
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "iterator_step_by", since = "1.28.0")]
 #[derive(Clone, Debug)]
 pub struct StepBy<I> {
@@ -849,7 +849,7 @@ impl<I> ExactSizeIterator for StepBy<I> where I: ExactSizeIterator {}
 /// [`chain`]: trait.Iterator.html#method.chain
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Chain<A, B> {
     a: A,
@@ -1100,7 +1100,7 @@ unsafe impl<A, B> TrustedLen for Chain<A, B>
 /// [`zip`]: trait.Iterator.html#method.zip
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Zip<A, B> {
     a: A,
@@ -1400,7 +1400,7 @@ unsafe impl<A, B> TrustedLen for Zip<A, B>
 ///     println!("{:?}", pair);
 /// }
 /// ```
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct Map<I, F> {
@@ -1511,7 +1511,7 @@ unsafe impl<B, I, F> TrustedRandomAccess for Map<I, F>
 ///
 /// [`filter`]: trait.Iterator.html#method.filter
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct Filter<I, P> {
@@ -1643,7 +1643,7 @@ impl<I: FusedIterator, P> FusedIterator for Filter<I, P>
 ///
 /// [`filter_map`]: trait.Iterator.html#method.filter_map
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct FilterMap<I, F> {
@@ -1754,7 +1754,7 @@ impl<B, I: FusedIterator, F> FusedIterator for FilterMap<I, F>
 /// [`enumerate`]: trait.Iterator.html#method.enumerate
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Enumerate<I> {
     iter: I,
@@ -1915,7 +1915,7 @@ unsafe impl<I> TrustedLen for Enumerate<I>
 /// [`peekable`]: trait.Iterator.html#method.peekable
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Peekable<I: Iterator> {
     iter: I,
@@ -2066,7 +2066,7 @@ impl<I: Iterator> Peekable<I> {
 ///
 /// [`skip_while`]: trait.Iterator.html#method.skip_while
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct SkipWhile<I, P> {
@@ -2149,7 +2149,7 @@ impl<I, P> FusedIterator for SkipWhile<I, P>
 ///
 /// [`take_while`]: trait.Iterator.html#method.take_while
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct TakeWhile<I, P> {
@@ -2233,7 +2233,7 @@ impl<I, P> FusedIterator for TakeWhile<I, P>
 /// [`skip`]: trait.Iterator.html#method.skip
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Skip<I> {
     iter: I,
@@ -2371,7 +2371,7 @@ impl<I> FusedIterator for Skip<I> where I: FusedIterator {}
 /// [`take`]: trait.Iterator.html#method.take
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Take<I> {
     iter: I,
@@ -2458,7 +2458,7 @@ unsafe impl<I: TrustedLen> TrustedLen for Take<I> {}
 ///
 /// [`scan`]: trait.Iterator.html#method.scan
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct Scan<I, St, F> {
@@ -2518,7 +2518,7 @@ impl<B, I, St, F> Iterator for Scan<I, St, F> where
 ///
 /// [`flat_map`]: trait.Iterator.html#method.flat_map
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct FlatMap<I, U: IntoIterator, F> {
     inner: FlattenCompat<Map<I, F>, <U as IntoIterator>::IntoIter>
@@ -2603,7 +2603,7 @@ impl<I, U, F> FusedIterator for FlatMap<I, U, F>
 ///
 /// [`flatten`]: trait.Iterator.html#method.flatten
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "iterator_flatten", since = "1.29.0")]
 pub struct Flatten<I: Iterator>
 where I::Item: IntoIterator {
@@ -2832,7 +2832,7 @@ impl<I, U> DoubleEndedIterator for FlattenCompat<I, U>
 /// [`fuse`]: trait.Iterator.html#method.fuse
 /// [`Iterator`]: trait.Iterator.html
 #[derive(Clone, Debug)]
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Fuse<I> {
     iter: I,
@@ -3056,7 +3056,7 @@ impl<I> ExactSizeIterator for Fuse<I> where I: ExactSizeIterator {
 ///
 /// [`inspect`]: trait.Iterator.html#method.inspect
 /// [`Iterator`]: trait.Iterator.html
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
+#[must_use = "iterators are lazy and do nothing unless consumed"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Clone)]
 pub struct Inspect<I, F> {

src/librustc_borrowck/borrowck/check_loans.rs

@@ -557,12 +557,8 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
                 if new_loan.loan_path.has_fork(&old_loan.loan_path) && common.is_some() {
                     let nl = self.bccx.loan_path_to_string(&common.unwrap());
                     let ol = nl.clone();
-                    let new_loan_msg = format!(" (via `{}`)",
-                                               self.bccx.loan_path_to_string(
-                                                   &new_loan.loan_path));
-                    let old_loan_msg = format!(" (via `{}`)",
-                                               self.bccx.loan_path_to_string(
-                                                   &old_loan.loan_path));
+                    let new_loan_msg = self.bccx.loan_path_to_string(&new_loan.loan_path);
+                    let old_loan_msg = self.bccx.loan_path_to_string(&old_loan.loan_path);
                     (nl, ol, new_loan_msg, old_loan_msg)
                 } else {
                     (self.bccx.loan_path_to_string(&new_loan.loan_path),

src/librustc_codegen_ssa/back/linker.rs

@@ -81,11 +81,7 @@ impl LinkerInfo {
             }
 
             LinkerFlavor::Lld(LldFlavor::Wasm) => {
-                Box::new(WasmLd {
-                    cmd,
-                    sess,
-                    info: self
-                }) as Box<dyn Linker>
+                Box::new(WasmLd::new(cmd, sess, self)) as Box<dyn Linker>
             }
         }
     }
@@ -876,6 +872,67 @@ pub struct WasmLd<'a> {
     info: &'a LinkerInfo,
 }
 
+impl<'a> WasmLd<'a> {
+    fn new(mut cmd: Command, sess: &'a Session, info: &'a LinkerInfo) -> WasmLd<'a> {
+        // There have been reports in the wild (rustwasm/wasm-bindgen#119) of
+        // using threads causing weird hangs and bugs. Disable it entirely as
+        // this isn't yet the bottleneck of compilation at all anyway.
+        cmd.arg("--no-threads");
+
+        // By default LLD only gives us one page of stack (64k) which is a
+        // little small. Default to a larger stack closer to other PC platforms
+        // (1MB) and users can always inject their own link-args to override this.
+        cmd.arg("-z").arg("stack-size=1048576");
+
+        // By default LLD's memory layout is:
+        //
+        // 1. First, a blank page
+        // 2. Next, all static data
+        // 3. Finally, the main stack (which grows down)
+        //
+        // This has the unfortunate consequence that on stack overflows you
+        // corrupt static data and can cause some exceedingly weird bugs. To
+        // help detect this a little sooner we instead request that the stack is
+        // placed before static data.
+        //
+        // This means that we'll generate slightly larger binaries as references
+        // to static data will take more bytes in the ULEB128 encoding, but
+        // stack overflow will be guaranteed to trap as it underflows instead of
+        // corrupting static data.
+        cmd.arg("--stack-first");
+
+        // FIXME we probably shouldn't pass this but instead pass an explicit
+        // whitelist of symbols we'll allow to be undefined. Unfortunately
+        // though we can't handle symbols like `log10` that LLVM injects at a
+        // super late date without actually parsing object files. For now let's
+        // stick to this and hopefully fix it before stabilization happens.
+        cmd.arg("--allow-undefined");
+
+        // For now we just never have an entry symbol
+        cmd.arg("--no-entry");
+
+        // Make the default table accessible
+        cmd.arg("--export-table");
+
+        // Rust code should never have warnings, and warnings are often
+        // indicative of bugs, let's prevent them.
+        cmd.arg("--fatal-warnings");
+
+        // The symbol visibility story is a bit in flux right now with LLD.
+        // It's... not entirely clear to me what's going on, but this looks to
+        // make everything work when `export_symbols` isn't otherwise called for
+        // things like executables.
+        cmd.arg("--export-dynamic");
+
+        // LLD only implements C++-like demangling, which doesn't match our own
+        // mangling scheme. Tell LLD to not demangle anything and leave it up to
+        // us to demangle these symbols later.
+        cmd.arg("--no-demangle");
+
+        WasmLd { cmd, sess, info }
+    }
+}
+
 impl<'a> Linker for WasmLd<'a> {
     fn link_dylib(&mut self, lib: &str) {
         self.cmd.arg("-l").arg(lib);
@@ -982,61 +1039,6 @@ impl<'a> Linker for WasmLd<'a> {
     }
 
     fn finalize(&mut self) -> Command {
-        // There have been reports in the wild (rustwasm/wasm-bindgen#119) of
-        // using threads causing weird hangs and bugs. Disable it entirely as
-        // this isn't yet the bottleneck of compilation at all anyway.
-        self.cmd.arg("--no-threads");
-
-        // By default LLD only gives us one page of stack (64k) which is a
-        // little small. Default to a larger stack closer to other PC platforms
-        // (1MB) and users can always inject their own link-args to override this.
-        self.cmd.arg("-z").arg("stack-size=1048576");
-
-        // By default LLD's memory layout is:
-        //
-        // 1. First, a blank page
-        // 2. Next, all static data
-        // 3. Finally, the main stack (which grows down)
-        //
-        // This has the unfortunate consequence that on stack overflows you
-        // corrupt static data and can cause some exceedingly weird bugs. To
-        // help detect this a little sooner we instead request that the stack is
-        // placed before static data.
-        //
-        // This means that we'll generate slightly larger binaries as references
-        // to static data will take more bytes in the ULEB128 encoding, but
-        // stack overflow will be guaranteed to trap as it underflows instead of
-        // corrupting static data.
-        self.cmd.arg("--stack-first");
-
-        // FIXME we probably shouldn't pass this but instead pass an explicit
-        // whitelist of symbols we'll allow to be undefined. Unfortunately
-        // though we can't handle symbols like `log10` that LLVM injects at a
-        // super late date without actually parsing object files. For now let's
-        // stick to this and hopefully fix it before stabilization happens.
-        self.cmd.arg("--allow-undefined");
-
-        // For now we just never have an entry symbol
-        self.cmd.arg("--no-entry");
-
-        // Make the default table accessible
-        self.cmd.arg("--export-table");
-
-        // Rust code should never have warnings, and warnings are often
-        // indicative of bugs, let's prevent them.
-        self.cmd.arg("--fatal-warnings");
-
-        // The symbol visibility story is a bit in flux right now with LLD.
-        // It's... not entirely clear to me what's going on, but this looks to
-        // make everything work when `export_symbols` isn't otherwise called for
-        // things like executables.
-        self.cmd.arg("--export-dynamic");
-
-        // LLD only implements C++-like demangling, which doesn't match our own
-        // mangling scheme. Tell LLD to not demangle anything and leave it up to
-        // us to demangle these symbols later.
-        self.cmd.arg("--no-demangle");
-
         ::std::mem::replace(&mut self.cmd, Command::new(""))
     }