Auto merge of #129841 - matthiaskrgr:rollup-pkavdtl, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - #128495 (core: use `compare_bytes` for more slice element types)
 - #128641 (refactor: standardize duplicate processes in parser)
 - #129207 (Lint that warns when an elided lifetime ends up being a named lifetime)
 - #129493 (Create opaque definitions in resolver.)
 - #129619 (Update stacker to 0.1.17)
 - #129672 (Make option-like-enum.rs UB-free and portable)
 - #129780 (add crashtests for several old unfixed ICEs)
 - #129832 (Remove stray dot in `std::char::from_u32_unchecked` documentation)

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

Cargo.lock

@@ -4978,15 +4978,15 @@ dependencies = [
 
 [[package]]
 name = "stacker"
-version = "0.1.15"
+version = "0.1.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c886bd4480155fd3ef527d45e9ac8dd7118a898a46530b7b94c3e21866259fce"
+checksum = "799c883d55abdb5e98af1a7b3f23b9b6de8ecada0ecac058672d7635eb48ca7b"
 dependencies = [
  "cc",
  "cfg-if",
  "libc",
  "psm",
- "winapi",
+ "windows-sys 0.59.0",
 ]
 
 [[package]]

compiler/rustc_ast/src/visit.rs

@@ -69,14 +69,14 @@ pub enum FnKind<'a> {
     Fn(FnCtxt, Ident, &'a FnSig, &'a Visibility, &'a Generics, Option<&'a Block>),
 
     /// E.g., `|x, y| body`.
-    Closure(&'a ClosureBinder, &'a FnDecl, &'a Expr),
+    Closure(&'a ClosureBinder, &'a Option<CoroutineKind>, &'a FnDecl, &'a Expr),
 }
 
 impl<'a> FnKind<'a> {
     pub fn header(&self) -> Option<&'a FnHeader> {
         match *self {
             FnKind::Fn(_, _, sig, _, _, _) => Some(&sig.header),
-            FnKind::Closure(_, _, _) => None,
+            FnKind::Closure(..) => None,
         }
     }
 
@@ -90,7 +90,7 @@ impl<'a> FnKind<'a> {
     pub fn decl(&self) -> &'a FnDecl {
         match self {
             FnKind::Fn(_, _, sig, _, _, _) => &sig.decl,
-            FnKind::Closure(_, decl, _) => decl,
+            FnKind::Closure(_, _, decl, _) => decl,
         }
     }
 
@@ -839,7 +839,7 @@ pub fn walk_fn<'a, V: Visitor<'a>>(visitor: &mut V, kind: FnKind<'a>) -> V::Resu
             try_visit!(walk_fn_decl(visitor, decl));
             visit_opt!(visitor, visit_block, body);
         }
-        FnKind::Closure(binder, decl, body) => {
+        FnKind::Closure(binder, _coroutine_kind, decl, body) => {
             try_visit!(visitor.visit_closure_binder(binder));
             try_visit!(walk_fn_decl(visitor, decl));
             try_visit!(visitor.visit_expr(body));
@@ -1107,7 +1107,7 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) -> V
         ExprKind::Closure(box Closure {
             binder,
             capture_clause,
-            coroutine_kind: _,
+            coroutine_kind,
             constness: _,
             movability: _,
             fn_decl,
@@ -1116,7 +1116,11 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) -> V
             fn_arg_span: _,
         }) => {
             try_visit!(visitor.visit_capture_by(capture_clause));
-            try_visit!(visitor.visit_fn(FnKind::Closure(binder, fn_decl, body), *span, *id))
+            try_visit!(visitor.visit_fn(
+                FnKind::Closure(binder, coroutine_kind, fn_decl, body),
+                *span,
+                *id
+            ))
         }
         ExprKind::Block(block, opt_label) => {
             visit_opt!(visitor, visit_label, opt_label);

compiler/rustc_ast_lowering/src/lib.rs

@@ -45,7 +45,6 @@ use std::collections::hash_map::Entry;
 use rustc_ast::node_id::NodeMap;
 use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, *};
-use rustc_ast_pretty::pprust;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxIndexSet;
@@ -837,7 +836,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
 
                 (hir::ParamName::Fresh, hir::LifetimeParamKind::Elided(kind))
             }
-            LifetimeRes::Static | LifetimeRes::Error => return None,
+            LifetimeRes::Static { .. } | LifetimeRes::Error => return None,
             res => panic!(
                 "Unexpected lifetime resolution {:?} for {:?} at {:?}",
                 res, ident, ident.span
@@ -1399,24 +1398,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             self.tcx.dcx().emit_err(errors::NoPreciseCapturesOnApit { span });
                         }
 
-                        let span = t.span;
-
-                        // HACK: pprust breaks strings with newlines when the type
-                        // gets too long. We don't want these to show up in compiler
-                        // output or built artifacts, so replace them here...
-                        // Perhaps we should instead format APITs more robustly.
-                        let ident = Ident::from_str_and_span(
-                            &pprust::ty_to_string(t).replace('\n', " "),
-                            span,
-                        );
-
-                        self.create_def(
-                            self.current_hir_id_owner.def_id, // FIXME: should this use self.current_def_id_parent?
-                            *def_node_id,
-                            ident.name,
-                            DefKind::TyParam,
-                            span,
-                        );
+                        let def_id = self.local_def_id(*def_node_id);
+                        let name = self.tcx.item_name(def_id.to_def_id());
+                        let ident = Ident::new(name, span);
                         let (param, bounds, path) = self.lower_universal_param_and_bounds(
                             *def_node_id,
                             span,
@@ -1618,13 +1602,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         opaque_ty_span: Span,
         lower_item_bounds: impl FnOnce(&mut Self) -> &'hir [hir::GenericBound<'hir>],
     ) -> hir::TyKind<'hir> {
-        let opaque_ty_def_id = self.create_def(
-            self.current_hir_id_owner.def_id, // FIXME: should this use self.current_def_id_parent?
-            opaque_ty_node_id,
-            kw::Empty,
-            DefKind::OpaqueTy,
-            opaque_ty_span,
-        );
+        let opaque_ty_def_id = self.local_def_id(opaque_ty_node_id);
         debug!(?opaque_ty_def_id);
 
         // Map from captured (old) lifetime to synthetic (new) lifetime.
@@ -1656,7 +1634,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 }
 
                 // Opaques do not capture `'static`
-                LifetimeRes::Static | LifetimeRes::Error => {
+                LifetimeRes::Static { .. } | LifetimeRes::Error => {
                     continue;
                 }
 
@@ -2069,7 +2047,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                 hir::LifetimeName::Param(param)
             }
             LifetimeRes::Infer => hir::LifetimeName::Infer,
-            LifetimeRes::Static => hir::LifetimeName::Static,
+            LifetimeRes::Static { .. } => hir::LifetimeName::Static,
             LifetimeRes::Error => hir::LifetimeName::Error,
             res => panic!(
                 "Unexpected lifetime resolution {:?} for {:?} at {:?}",

compiler/rustc_ast_lowering/src/lifetime_collector.rs

@@ -27,7 +27,7 @@ impl<'ast> LifetimeCollectVisitor<'ast> {
                     self.collected_lifetimes.insert(lifetime);
                 }
             }
-            LifetimeRes::Static | LifetimeRes::Error => {
+            LifetimeRes::Static { .. } | LifetimeRes::Error => {
                 self.collected_lifetimes.insert(lifetime);
             }
             LifetimeRes::Infer => {}

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1485,7 +1485,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
 
         let disallowed = (!tilde_const_allowed).then(|| match fk {
             FnKind::Fn(_, ident, _, _, _, _) => TildeConstReason::Function { ident: ident.span },
-            FnKind::Closure(_, _, _) => TildeConstReason::Closure,
+            FnKind::Closure(..) => TildeConstReason::Closure,
         });
         self.with_tilde_const(disallowed, |this| visit::walk_fn(this, fk));
     }

compiler/rustc_data_structures/Cargo.toml

@@ -22,7 +22,7 @@ rustc_index = { path = "../rustc_index", package = "rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 smallvec = { version = "1.8.1", features = ["const_generics", "union", "may_dangle"] }
-stacker = "0.1.15"
+stacker = "0.1.17"
 tempfile = "3.2"
 thin-vec = "0.2.12"
 tracing = "0.1"

compiler/rustc_hir/src/def.rs

@@ -863,8 +863,13 @@ pub enum LifetimeRes {
     /// This variant is used for anonymous lifetimes that we did not resolve during
     /// late resolution. Those lifetimes will be inferred by typechecking.
     Infer,
-    /// Explicit `'static` lifetime.
-    Static,
+    /// `'static` lifetime.
+    Static {
+        /// We do not want to emit `elided_named_lifetimes`
+        /// when we are inside of a const item or a static,
+        /// because it would get too annoying.
+        suppress_elision_warning: bool,
+    },
     /// Resolution failure.
     Error,
     /// HACK: This is used to recover the NodeId of an elided lifetime.

compiler/rustc_lint/messages.ftl

@@ -252,6 +252,10 @@ lint_duplicate_macro_attribute =
 
 lint_duplicate_matcher_binding = duplicate matcher binding
 
+lint_elided_named_lifetime = elided lifetime has a name
+    .label_elided = this elided lifetime gets resolved as `{$name}`
+    .label_named = lifetime `{$name}` declared here
+
 lint_enum_intrinsics_mem_discriminant =
     the return value of `mem::discriminant` is unspecified when called with a non-enum type
     .note = the argument to `discriminant` should be a reference to an enum, but it was passed a reference to a `{$ty_param}`, which is not an enum

compiler/rustc_lint/src/context/diagnostics.rs

@@ -10,6 +10,7 @@ use rustc_errors::{
 use rustc_middle::middle::stability;
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::Session;
+use rustc_span::symbol::kw;
 use rustc_span::BytePos;
 use tracing::debug;
 
@@ -441,5 +442,17 @@ pub(super) fn decorate_lint(sess: &Session, diagnostic: BuiltinLintDiag, diag: &
         BuiltinLintDiag::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by } => {
             lints::UnexpectedBuiltinCfg { cfg, cfg_name, controlled_by }.decorate_lint(diag)
         }
+        BuiltinLintDiag::ElidedIsStatic { elided } => {
+            lints::ElidedNamedLifetime { elided, name: kw::StaticLifetime, named_declaration: None }
+                .decorate_lint(diag)
+        }
+        BuiltinLintDiag::ElidedIsParam { elided, param: (param_name, param_span) } => {
+            lints::ElidedNamedLifetime {
+                elided,
+                name: param_name,
+                named_declaration: Some(param_span),
+            }
+            .decorate_lint(diag)
+        }
     }
 }

compiler/rustc_lint/src/lints.rs

@@ -2611,6 +2611,16 @@ pub(crate) struct ElidedLifetimesInPaths {
     pub subdiag: ElidedLifetimeInPathSubdiag,
 }
 
+#[derive(LintDiagnostic)]
+#[diag(lint_elided_named_lifetime)]
+pub(crate) struct ElidedNamedLifetime {
+    #[label(lint_label_elided)]
+    pub elided: Span,
+    pub name: Symbol,
+    #[label(lint_label_named)]
+    pub named_declaration: Option<Span>,
+}
+
 #[derive(LintDiagnostic)]
 #[diag(lint_invalid_crate_type_value)]
 pub(crate) struct UnknownCrateTypes {

compiler/rustc_lint_defs/src/builtin.rs

@@ -42,6 +42,7 @@ declare_lint_pass! {
         DUPLICATE_MACRO_ATTRIBUTES,
         ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
         ELIDED_LIFETIMES_IN_PATHS,
+        ELIDED_NAMED_LIFETIMES,
         EXPLICIT_BUILTIN_CFGS_IN_FLAGS,
         EXPORTED_PRIVATE_DEPENDENCIES,
         FFI_UNWIND_CALLS,
@@ -1862,6 +1863,38 @@ declare_lint! {
     "hidden lifetime parameters in types are deprecated"
 }
 
+declare_lint! {
+    /// The `elided_named_lifetimes` lint detects when an elided
+    /// lifetime ends up being a named lifetime, such as `'static`
+    /// or some lifetime parameter `'a`.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![deny(elided_named_lifetimes)]
+    /// struct Foo;
+    /// impl Foo {
+    ///     pub fn get_mut(&'static self, x: &mut u8) -> &mut u8 {
+    ///         unsafe { &mut *(x as *mut _) }
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Lifetime elision is quite useful, because it frees you from having
+    /// to give each lifetime its own name, but sometimes it can produce
+    /// somewhat surprising resolutions. In safe code, it is mostly okay,
+    /// because the borrow checker prevents any unsoundness, so the worst
+    /// case scenario is you get a confusing error message in some other place.
+    /// But with `unsafe` code, such unexpected resolutions may lead to unsound code.
+    pub ELIDED_NAMED_LIFETIMES,
+    Warn,
+    "detects when an elided lifetime gets resolved to be `'static` or some named parameter"
+}
+
 declare_lint! {
     /// The `bare_trait_objects` lint suggests using `dyn Trait` for trait
     /// objects.

compiler/rustc_lint_defs/src/lib.rs

@@ -589,6 +589,13 @@ pub enum BuiltinLintDiag {
     },
     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
     ElidedLifetimesInPaths(usize, Span, bool, Span),
+    ElidedIsStatic {
+        elided: Span,
+    },
+    ElidedIsParam {
+        elided: Span,
+        param: (Symbol, Span),
+    },
     UnknownCrateTypes {
         span: Span,
         candidate: Option<Symbol>,