Auto merge of #82341 - GuillaumeGomez:rollup-t7y7tyg, r=GuillaumeGomez

Rollup of 7 pull requests

Successful merges:

 - #80595 (`impl PartialEq<Punct> for char`; symmetry for #78636)
 - #81991 (Fix panic in 'remove semicolon' when types are not local)
 - #82176 (fix MIR fn-ptr pretty-printing)
 - #82244 (Keep consistency in example for Stdin StdinLock)
 - #82260 (rustc: Show ``@path`` usage in stable)
 - #82316 (Fix minor mistake in LTO docs.)
 - #82332 (Don't generate src link on dummy spans)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

14 files changed, 117 insertions, 25 deletions

diff --git a/compiler/rustc_driver/src/lib.rs b/compiler/rustc_driver/src/lib.rs
index 07c7278a2f4..79bb21b29fc 100644
--- a/compiler/rustc_driver/src/lib.rs
+++ b/compiler/rustc_driver/src/lib.rs
@@ -812,7 +812,7 @@ fn usage(verbose: bool, include_unstable_options: bool, nightly_build: bool) {
     } else {
         "\n    --help -v           Print the full set of options rustc accepts"
     };
-    let at_path = if verbose && nightly_build {
+    let at_path = if verbose {
         "    @path               Read newline separated options from `path`\n"
     } else {
         ""
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 64604b6459f..53c164d44b3 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1018,7 +1018,7 @@ pub trait PrettyPrinter<'tcx>:
                 p!(write("{:?}", char::try_from(int).unwrap()))
             }
             // Raw pointers
-            (Scalar::Int(int), ty::RawPtr(_)) => {
+            (Scalar::Int(int), ty::RawPtr(_) | ty::FnPtr(_)) => {
                 let data = int.assert_bits(self.tcx().data_layout.pointer_size);
                 self = self.typed_value(
                     |mut this| {
@@ -1030,15 +1030,18 @@ pub trait PrettyPrinter<'tcx>:
                 )?;
             }
             (Scalar::Ptr(ptr), ty::FnPtr(_)) => {
-                // FIXME: this can ICE when the ptr is dangling or points to a non-function.
-                // We should probably have a helper method to share code with the "Byte strings"
+                // FIXME: We should probably have a helper method to share code with the "Byte strings"
                 // printing above (which also has to handle pointers to all sorts of things).
-                let instance = self.tcx().global_alloc(ptr.alloc_id).unwrap_fn();
-                self = self.typed_value(
-                    |this| this.print_value_path(instance.def_id(), instance.substs),
-                    |this| this.print_type(ty),
-                    " as ",
-                )?;
+                match self.tcx().get_global_alloc(ptr.alloc_id) {
+                    Some(GlobalAlloc::Function(instance)) => {
+                        self = self.typed_value(
+                            |this| this.print_value_path(instance.def_id(), instance.substs),
+                            |this| this.print_type(ty),
+                            " as ",
+                        )?;
+                    }
+                    _ => self = self.pretty_print_const_pointer(ptr, ty, print_ty)?,
+                }
             }
             // For function type zsts just printing the path is enough
             (Scalar::Int(int), ty::FnDef(d, s)) if int == ScalarInt::ZST => {
diff --git a/compiler/rustc_mir/src/interpret/operand.rs b/compiler/rustc_mir/src/interpret/operand.rs
index f85191f459f..46ecd33cc5b 100644
--- a/compiler/rustc_mir/src/interpret/operand.rs
+++ b/compiler/rustc_mir/src/interpret/operand.rs
@@ -112,7 +112,7 @@ impl<Tag: Copy> std::fmt::Display for ImmTy<'tcx, Tag> {
                 }
                 ScalarMaybeUninit::Uninit => cx.typed_value(
                     |mut this| {
-                        this.write_str("{uninit ")?;
+                        this.write_str("uninit ")?;
                         Ok(this)
                     },
                     |this| this.print_type(ty),
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
index 7f27325f7f9..f5e9cc1efcc 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs
@@ -1074,13 +1074,26 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
         let last_expr_ty = self.node_ty(last_expr.hir_id);
         let needs_box = match (last_expr_ty.kind(), expected_ty.kind()) {
+            (ty::Opaque(last_def_id, _), ty::Opaque(exp_def_id, _))
+                if last_def_id == exp_def_id =>
+            {
+                StatementAsExpression::CorrectType
+            }
             (ty::Opaque(last_def_id, last_bounds), ty::Opaque(exp_def_id, exp_bounds)) => {
                 debug!(
                     "both opaque, likely future {:?} {:?} {:?} {:?}",
                     last_def_id, last_bounds, exp_def_id, exp_bounds
                 );
-                let last_hir_id = self.tcx.hir().local_def_id_to_hir_id(last_def_id.expect_local());
-                let exp_hir_id = self.tcx.hir().local_def_id_to_hir_id(exp_def_id.expect_local());
+
+                let (last_local_id, exp_local_id) =
+                    match (last_def_id.as_local(), exp_def_id.as_local()) {
+                        (Some(last_hir_id), Some(exp_hir_id)) => (last_hir_id, exp_hir_id),
+                        (_, _) => return None,
+                    };
+
+                let last_hir_id = self.tcx.hir().local_def_id_to_hir_id(last_local_id);
+                let exp_hir_id = self.tcx.hir().local_def_id_to_hir_id(exp_local_id);
+
                 match (
                     &self.tcx.hir().expect_item(last_hir_id).kind,
                     &self.tcx.hir().expect_item(exp_hir_id).kind,
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index a89e7b53e43..5f1f7d8cac4 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -842,13 +842,20 @@ impl fmt::Debug for Punct {
     }
 }
 
-#[stable(feature = "proc_macro_punct_eq", since = "1.49.0")]
+#[stable(feature = "proc_macro_punct_eq", since = "1.50.0")]
 impl PartialEq<char> for Punct {
     fn eq(&self, rhs: &char) -> bool {
         self.as_char() == *rhs
     }
 }
 
+#[stable(feature = "proc_macro_punct_eq_flipped", since = "1.52.0")]
+impl PartialEq<Punct> for char {
+    fn eq(&self, rhs: &Punct) -> bool {
+        *self == rhs.as_char()
+    }
+}
+
 /// An identifier (`ident`).
 #[derive(Clone)]
 #[stable(feature = "proc_macro_lib2", since = "1.29.0")]
diff --git a/library/std/src/io/stdio.rs b/library/std/src/io/stdio.rs
index e736bf19e8f..d1f9049c8fa 100644
--- a/library/std/src/io/stdio.rs
+++ b/library/std/src/io/stdio.rs
@@ -251,8 +251,8 @@ pub struct Stdin {
 ///     let mut buffer = String::new();
 ///     let stdin = io::stdin(); // We get `Stdin` here.
 ///     {
-///         let mut stdin_lock = stdin.lock(); // We get `StdinLock` here.
-///         stdin_lock.read_to_string(&mut buffer)?;
+///         let mut handle = stdin.lock(); // We get `StdinLock` here.
+///         handle.read_to_string(&mut buffer)?;
 ///     } // `StdinLock` is dropped here.
 ///     Ok(())
 /// }
diff --git a/src/doc/rustc/src/codegen-options/index.md b/src/doc/rustc/src/codegen-options/index.md
index 51e7d987d9d..1883346430b 100644
--- a/src/doc/rustc/src/codegen-options/index.md
+++ b/src/doc/rustc/src/codegen-options/index.md
@@ -299,9 +299,9 @@ opt-level=0`](#opt-level)). That is:
 * When `-C lto` is not specified:
   * `codegen-units=1`: disable LTO.
   * `opt-level=0`: disable LTO.
-* When `-C lto=true`:
-  * `lto=true`: 16 codegen units, perform fat LTO across crates.
-  * `codegen-units=1` + `lto=true`: 1 codegen unit, fat LTO across crates.
+* When `-C lto` is specified:
+  * `lto`: 16 codegen units, perform fat LTO across crates.
+  * `codegen-units=1` + `lto`: 1 codegen unit, fat LTO across crates.
 
 See also [linker-plugin-lto](#linker-plugin-lto) for cross-language LTO.
 
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 3e7196fa7fa..9a2319f6e37 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1852,6 +1852,10 @@ impl Span {
         self.0
     }
 
+    crate fn is_dummy(&self) -> bool {
+        self.0.is_dummy()
+    }
+
     crate fn filename(&self, sess: &Session) -> FileName {
         sess.source_map().span_to_filename(self.0)
     }
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index f5eb92c1bb5..7ca355ed11c 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -1638,6 +1638,9 @@ impl Context<'_> {
     /// may happen, for example, with externally inlined items where the source
     /// of their crate documentation isn't known.
     fn src_href(&self, item: &clean::Item) -> Option<String> {
+        if item.source.is_dummy() {
+            return None;
+        }
         let mut root = self.root_path();
         let mut path = String::new();
         let cnum = item.source.cnum(self.sess());
diff --git a/src/test/rustdoc/src-links-auto-impls.rs b/src/test/rustdoc/src-links-auto-impls.rs
new file mode 100644
index 00000000000..a1d183df0f1
--- /dev/null
+++ b/src/test/rustdoc/src-links-auto-impls.rs
@@ -0,0 +1,12 @@
+#![crate_name = "foo"]
+
+// @has foo/struct.Unsized.html
+// @has - '//h3[@id="impl-Sized"]/code' 'impl !Sized for Unsized'
+// @!has - '//h3[@id="impl-Sized"]/a[@class="srclink"]' '[src]'
+// @has - '//h3[@id="impl-Sync"]/code' 'impl Sync for Unsized'
+// @!has - '//h3[@id="impl-Sync"]/a[@class="srclink"]' '[src]'
+// @has - '//h3[@id="impl-Any"]/code' 'impl<T> Any for T'
+// @has - '//h3[@id="impl-Any"]/a[@class="srclink"]' '[src]'
+pub struct Unsized {
+    data: [u8],
+}
diff --git a/src/test/ui/suggestions/auxiliary/issue-81839.rs b/src/test/ui/suggestions/auxiliary/issue-81839.rs
new file mode 100644
index 00000000000..5683c45adf2
--- /dev/null
+++ b/src/test/ui/suggestions/auxiliary/issue-81839.rs
@@ -0,0 +1,9 @@
+// edition:2018
+
+pub struct Test {}
+
+impl Test {
+    pub async fn answer_str(&self, _s: &str) -> Test {
+        Test {}
+    }
+}
diff --git a/src/test/ui/suggestions/issue-81839.rs b/src/test/ui/suggestions/issue-81839.rs
new file mode 100644
index 00000000000..0b9b7aefe73
--- /dev/null
+++ b/src/test/ui/suggestions/issue-81839.rs
@@ -0,0 +1,17 @@
+// aux-build:issue-81839.rs
+// edition:2018
+
+extern crate issue_81839;
+
+async fn test(ans: &str, num: i32, cx: &issue_81839::Test) -> u32 {
+    match num {
+        1 => {
+            cx.answer_str("hi");
+        }
+        _ => cx.answer_str("hi"), //~ `match` arms have incompatible types
+    }
+
+    1
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/issue-81839.stderr b/src/test/ui/suggestions/issue-81839.stderr
new file mode 100644
index 00000000000..1a289d39e44
--- /dev/null
+++ b/src/test/ui/suggestions/issue-81839.stderr
@@ -0,0 +1,27 @@
+error[E0308]: `match` arms have incompatible types
+  --> $DIR/issue-81839.rs:11:14
+   |
+LL | /     match num {
+LL | |         1 => {
+LL | |             cx.answer_str("hi");
+   | |             --------------------
+   | |             |                  |
+   | |             |                  help: consider removing this semicolon
+   | |             this is found to be of type `()`
+LL | |         }
+LL | |         _ => cx.answer_str("hi"),
+   | |              ^^^^^^^^^^^^^^^^^^^ expected `()`, found opaque type
+LL | |     }
+   | |_____- `match` arms have incompatible types
+   | 
+  ::: $DIR/auxiliary/issue-81839.rs:6:49
+   |
+LL |       pub async fn answer_str(&self, _s: &str) -> Test {
+   |                                                   ---- the `Output` of this `async fn`'s found opaque type
+   |
+   = note:     expected type `()`
+           found opaque type `impl Future`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/suggestions/match-prev-arm-needing-semi.stderr b/src/test/ui/suggestions/match-prev-arm-needing-semi.stderr
index e9803a78f94..fae0c498b44 100644
--- a/src/test/ui/suggestions/match-prev-arm-needing-semi.stderr
+++ b/src/test/ui/suggestions/match-prev-arm-needing-semi.stderr
@@ -24,13 +24,10 @@ help: consider `await`ing on the `Future`
    |
 LL |         false => async_dummy().await,
    |                               ^^^^^^
-help: consider removing this semicolon and boxing the expressions
-   |
-LL |             Box::new(async_dummy())
-LL |
-LL |         }
-LL |         false => Box::new(async_dummy()),
+help: consider removing this semicolon
    |
+LL |             async_dummy()
+   |                         --
 
 error[E0308]: `match` arms have incompatible types
   --> $DIR/match-prev-arm-needing-semi.rs:39:18