Auto merge of rust-lang#92434 - matthiaskrgr:rollup-m8wuq0v, r=matthiaskrgr

Rollup of 4 pull requests

Successful merges:

 - rust-lang#91519 (ast: Avoid aborts on fatal errors thrown from mutable AST visitor)
 - rust-lang#92414 (Fix spacing of pretty printed const item without body)
 - rust-lang#92423 (Add UI test for rust-lang#92292)
 - rust-lang#92427 (Use `UnsafeCell::get_mut()` in `core::lazy::OnceCell::get_mut()`)

Failed merges:

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

Author: bors

compiler/rustc_ast/src/mut_visit.rs

@@ -14,13 +14,14 @@ use crate::tokenstream::*;
 
 use rustc_data_structures::map_in_place::MapInPlace;
 use rustc_data_structures::sync::Lrc;
+use rustc_data_structures::thin_vec::ThinVec;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
 
 use smallvec::{smallvec, Array, SmallVec};
 use std::ops::DerefMut;
-use std::{panic, process, ptr};
+use std::{panic, ptr};
 
 pub trait ExpectOne<A: Array> {
     fn expect_one(self, err: &'static str) -> A::Item;
@@ -283,23 +284,21 @@ pub trait MutVisitor: Sized {
 
 /// Use a map-style function (`FnOnce(T) -> T`) to overwrite a `&mut T`. Useful
 /// when using a `flat_map_*` or `filter_map_*` method within a `visit_`
-/// method. Abort the program if the closure panics.
-///
-/// FIXME: Abort on panic means that any fatal error inside `visit_clobber` will abort the compiler.
-/// Instead of aborting on catching a panic we need to reset the visited node to some valid but
-/// possibly meaningless value and rethrow the panic.
+/// method.
 //
 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
-pub fn visit_clobber<T, F>(t: &mut T, f: F)
-where
-    F: FnOnce(T) -> T,
-{
+pub fn visit_clobber<T: DummyAstNode>(t: &mut T, f: impl FnOnce(T) -> T) {
     unsafe {
         // Safe because `t` is used in a read-only fashion by `read()` before
         // being overwritten by `write()`.
         let old_t = ptr::read(t);
-        let new_t = panic::catch_unwind(panic::AssertUnwindSafe(|| f(old_t)))
-            .unwrap_or_else(|_| process::abort());
+        let new_t =
+            panic::catch_unwind(panic::AssertUnwindSafe(|| f(old_t))).unwrap_or_else(|err| {
+                // Set `t` to some valid but possible meaningless value,
+                // and pass the fatal error further.
+                ptr::write(t, T::dummy());
+                panic::resume_unwind(err);
+            });
         ptr::write(t, new_t);
     }
 }
@@ -1454,3 +1453,108 @@ pub fn noop_visit_vis<T: MutVisitor>(visibility: &mut Visibility, vis: &mut T) {
     }
     vis.visit_span(&mut visibility.span);
 }
+
+/// Some value for the AST node that is valid but possibly meaningless.
+pub trait DummyAstNode {
+    fn dummy() -> Self;
+}
+
+impl<T> DummyAstNode for Option<T> {
+    fn dummy() -> Self {
+        Default::default()
+    }
+}
+
+impl<T: DummyAstNode + 'static> DummyAstNode for P<T> {
+    fn dummy() -> Self {
+        P(DummyAstNode::dummy())
+    }
+}
+
+impl<T> DummyAstNode for ThinVec<T> {
+    fn dummy() -> Self {
+        Default::default()
+    }
+}
+
+impl DummyAstNode for Item {
+    fn dummy() -> Self {
+        Item {
+            attrs: Default::default(),
+            id: DUMMY_NODE_ID,
+            span: Default::default(),
+            vis: Visibility {
+                kind: VisibilityKind::Public,
+                span: Default::default(),
+                tokens: Default::default(),
+            },
+            ident: Ident::empty(),
+            kind: ItemKind::ExternCrate(None),
+            tokens: Default::default(),
+        }
+    }
+}
+
+impl DummyAstNode for Expr {
+    fn dummy() -> Self {
+        Expr {
+            id: DUMMY_NODE_ID,
+            kind: ExprKind::Err,
+            span: Default::default(),
+            attrs: Default::default(),
+            tokens: Default::default(),
+        }
+    }
+}
+
+impl DummyAstNode for Ty {
+    fn dummy() -> Self {
+        Ty {
+            id: DUMMY_NODE_ID,
+            kind: TyKind::Err,
+            span: Default::default(),
+            tokens: Default::default(),
+        }
+    }
+}
+
+impl DummyAstNode for Pat {
+    fn dummy() -> Self {
+        Pat {
+            id: DUMMY_NODE_ID,
+            kind: PatKind::Wild,
+            span: Default::default(),
+            tokens: Default::default(),
+        }
+    }
+}
+
+impl DummyAstNode for Stmt {
+    fn dummy() -> Self {
+        Stmt { id: DUMMY_NODE_ID, kind: StmtKind::Empty, span: Default::default() }
+    }
+}
+
+impl DummyAstNode for Block {
+    fn dummy() -> Self {
+        Block {
+            stmts: Default::default(),
+            id: DUMMY_NODE_ID,
+            rules: BlockCheckMode::Default,
+            span: Default::default(),
+            tokens: Default::default(),
+            could_be_bare_literal: Default::default(),
+        }
+    }
+}
+
+impl DummyAstNode for Crate {
+    fn dummy() -> Self {
+        Crate {
+            attrs: Default::default(),
+            items: Default::default(),
+            span: Default::default(),
+            is_placeholder: Default::default(),
+        }
+    }
+}

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1116,7 +1116,9 @@ impl<'a> State<'a> {
         self.print_ident(ident);
         self.word_space(":");
         self.print_type(ty);
-        self.space();
+        if body.is_some() {
+            self.space();
+        }
         self.end(); // end the head-ibox
         if let Some(body) = body {
             self.word_space("=");

compiler/rustc_expand/src/expand.rs

@@ -1160,13 +1160,18 @@ macro_rules! assign_id {
 
 impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
     fn visit_crate(&mut self, krate: &mut ast::Crate) {
-        let span = krate.span;
-        let empty_crate =
-            || ast::Crate { attrs: Vec::new(), items: Vec::new(), span, is_placeholder: None };
-        let mut fold_crate = |krate: ast::Crate| {
+        visit_clobber(krate, |krate| {
+            let span = krate.span;
             let mut krate = match self.configure(krate) {
                 Some(krate) => krate,
-                None => return empty_crate(),
+                None => {
+                    return ast::Crate {
+                        attrs: Vec::new(),
+                        items: Vec::new(),
+                        span,
+                        is_placeholder: None,
+                    };
+                }
             };
 
             if let Some(attr) = self.take_first_attr(&mut krate) {
@@ -1177,10 +1182,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
 
             noop_visit_crate(&mut krate, self);
             krate
-        };
-
-        // Cannot use `visit_clobber` here, see the FIXME on it.
-        *krate = fold_crate(mem::replace(krate, empty_crate()));
+        })
     }
 
     fn visit_expr(&mut self, expr: &mut P<ast::Expr>) {

library/core/src/lazy.rs

@@ -102,8 +102,7 @@ impl<T> OnceCell<T> {
     /// Returns `None` if the cell is empty.
     #[unstable(feature = "once_cell", issue = "74465")]
     pub fn get_mut(&mut self) -> Option<&mut T> {
-        // SAFETY: Safe because we have unique access
-        unsafe { &mut *self.inner.get() }.as_mut()
+        self.inner.get_mut().as_mut()
     }
 
     /// Sets the contents of the cell to `value`.

src/test/pretty/nested-item-vis-defaultness.rs

@@ -6,42 +6,42 @@ fn main() {}
 
 #[cfg(FALSE)]
 extern "C" {
-    static X: u8 ;
+    static X: u8;
     type X;
     fn foo();
-    pub static X: u8 ;
+    pub static X: u8;
     pub type X;
     pub fn foo();
 }
 
 #[cfg(FALSE)]
 trait T {
-    const X: u8 ;
+    const X: u8;
     type X;
     fn foo();
-    default const X: u8 ;
+    default const X: u8;
     default type X;
     default fn foo();
-    pub const X: u8 ;
+    pub const X: u8;
     pub type X;
     pub fn foo();
-    pub default const X: u8 ;
+    pub default const X: u8;
     pub default type X;
     pub default fn foo();
 }
 
 #[cfg(FALSE)]
 impl T for S {
-    const X: u8 ;
+    const X: u8;
     type X;
     fn foo();
-    default const X: u8 ;
+    default const X: u8;
     default type X;
     default fn foo();
-    pub const X: u8 ;
+    pub const X: u8;
     pub type X;
     pub fn foo();
-    pub default const X: u8 ;
+    pub default const X: u8;
     pub default type X;
     pub default fn foo();
 }

src/test/ui/macros/stringify.rs

@@ -382,13 +382,13 @@ fn test_item() {
         stringify_item!(
             static S: ();
         ),
-        "static S: () ;", // FIXME
+        "static S: ();",
     );
     assert_eq!(
         stringify_item!(
             static mut S: ();
         ),
-        "static mut S: () ;",
+        "static mut S: ();",
     );
 
     // ItemKind::Const
@@ -402,7 +402,7 @@ fn test_item() {
         stringify_item!(
             const S: ();
         ),
-        "const S: () ;", // FIXME
+        "const S: ();",
     );
 
     // ItemKind::Fn

src/test/ui/traits/issue-92292.rs

@@ -0,0 +1,32 @@
+// check-pass
+
+use std::marker::PhantomData;
+
+pub struct MyGenericType<T> {
+    _marker: PhantomData<*const T>,
+}
+
+pub struct MyNonGenericType;
+
+impl<T> From<MyGenericType<T>> for MyNonGenericType {
+    fn from(_: MyGenericType<T>) -> Self {
+        todo!()
+    }
+}
+
+pub trait MyTrait {
+    const MY_CONSTANT: i32;
+}
+
+impl<T> MyTrait for MyGenericType<T>
+where
+    Self: Into<MyNonGenericType>,
+{
+    const MY_CONSTANT: i32 = 1;
+}
+
+impl<T> MyGenericType<T> {
+    const MY_OTHER_CONSTANT: i32 = <MyGenericType<T> as MyTrait>::MY_CONSTANT;
+}
+
+fn main() {}