Rollup of 7 pull requests

compiler/rustc_driver/src/lib.rs

@@ -1296,10 +1296,55 @@ pub fn init_env_logger(env: &str) {
     tracing::subscriber::set_global_default(subscriber).unwrap();
 }
 
+#[cfg(unix)]
+extern "C" {
+    fn backtrace_symbols_fd(buffer: *const *mut libc::c_void, size: libc::c_int, fd: libc::c_int);
+}
+
+#[cfg(unix)]
+extern "C" fn print_stack_trace(_: libc::c_int) {
+    const MAX_FRAMES: usize = 256;
+    static mut STACK_TRACE: [*mut libc::c_void; MAX_FRAMES] = [std::ptr::null_mut(); MAX_FRAMES];
+    unsafe {
+        let depth = libc::backtrace(STACK_TRACE.as_mut_ptr(), MAX_FRAMES as i32);
+        if depth == 0 {
+            return;
+        }
+        backtrace_symbols_fd(STACK_TRACE.as_ptr(), depth, 2);
+    }
+}
+
+#[cfg(unix)]
+// When an error signal (such as SIGABRT or SIGSEGV) is delivered to the
+// process, print a stack trace and then exit.
+fn install_signal_handler() {
+    unsafe {
+        const ALT_STACK_SIZE: usize = libc::MINSIGSTKSZ + 64 * 1024;
+        let mut alt_stack: libc::stack_t = std::mem::zeroed();
+        alt_stack.ss_sp =
+            std::alloc::alloc(std::alloc::Layout::from_size_align(ALT_STACK_SIZE, 1).unwrap())
+                as *mut libc::c_void;
+        alt_stack.ss_size = ALT_STACK_SIZE;
+        libc::sigaltstack(&mut alt_stack, std::ptr::null_mut());
+
+        let mut sa: libc::sigaction = std::mem::zeroed();
+        sa.sa_sigaction = print_stack_trace as libc::sighandler_t;
+        sa.sa_flags = libc::SA_NODEFER | libc::SA_RESETHAND | libc::SA_ONSTACK;
+        libc::sigemptyset(&mut sa.sa_mask);
+        libc::sigaction(libc::SIGSEGV, &sa, std::ptr::null_mut());
+    }
+}
+
+#[cfg(not(unix))]
+// When an error signal (such as SIGABRT or SIGSEGV) is delivered to the
+// process, print a stack trace and then exit.
+fn install_signal_handler() {}
+
 pub fn main() -> ! {
     let start_time = Instant::now();
     let start_rss = get_resident_set_size();
     init_rustc_env_logger();
+    install_signal_handler();
     let mut callbacks = TimePassesCallbacks::default();
     install_ice_hook();
     let exit_code = catch_with_exit_code(|| {

compiler/rustc_hir/src/hir.rs

@@ -2815,6 +2815,27 @@ impl ItemKind<'_> {
             _ => return None,
         })
     }
+
+    pub fn descr(&self) -> &'static str {
+        match self {
+            ItemKind::ExternCrate(..) => "extern crate",
+            ItemKind::Use(..) => "`use` import",
+            ItemKind::Static(..) => "static item",
+            ItemKind::Const(..) => "constant item",
+            ItemKind::Fn(..) => "function",
+            ItemKind::Mod(..) => "module",
+            ItemKind::ForeignMod { .. } => "extern block",
+            ItemKind::GlobalAsm(..) => "global asm item",
+            ItemKind::TyAlias(..) => "type alias",
+            ItemKind::OpaqueTy(..) => "opaque type",
+            ItemKind::Enum(..) => "enum",
+            ItemKind::Struct(..) => "struct",
+            ItemKind::Union(..) => "union",
+            ItemKind::Trait(..) => "trait",
+            ItemKind::TraitAlias(..) => "trait alias",
+            ItemKind::Impl(..) => "implementation",
+        }
+    }
 }
 
 /// A reference from an trait to one of its associated items. This

compiler/rustc_lint_defs/src/builtin.rs

@@ -3001,6 +3001,7 @@ declare_lint_pass! {
         PROC_MACRO_BACK_COMPAT,
         OR_PATTERNS_BACK_COMPAT,
         LARGE_ASSIGNMENTS,
+        FUTURE_PRELUDE_COLLISION,
     ]
 }
 
@@ -3244,3 +3245,52 @@ declare_lint! {
         edition: Some(Edition::Edition2021),
     };
 }
+
+declare_lint! {
+    /// The `future_prelude_collision` lint detects the usage of trait methods which are ambiguous
+    /// with traits added to the prelude in future editions.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![deny(future_prelude_collision)]
+    ///
+    /// trait Foo {
+    ///     fn try_into(self) -> Result<String, !>;
+    /// }
+    ///
+    /// impl Foo for &str {
+    ///     fn try_into(self) -> Result<String, !> {
+    ///         Ok(String::from(self))
+    ///     }
+    /// }
+    ///
+    /// fn main() {
+    ///     let x: String = "3".try_into().unwrap();
+    ///     //                  ^^^^^^^^
+    ///     // This call to try_into matches both Foo:try_into and TryInto::try_into as
+    ///     // `TryInto` has been added to the Rust prelude in 2021 edition.
+    ///     println!("{}", x);
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// In Rust 2021, one of the important introductions is the [prelude changes], which add
+    /// `TryFrom`, `TryInto`, and `FromIterator` into the standard library's prelude. Since this
+    /// results in an amiguity as to which method/function to call when an existing `try_into`
+    ///  method is called via dot-call syntax or a `try_from`/`from_iter` associated function
+    ///  is called directly on a type.
+    ///
+    /// [prelude changes]: https://blog.rust-lang.org/inside-rust/2021/03/04/planning-rust-2021.html#prelude-changes
+    pub FUTURE_PRELUDE_COLLISION,
+    Allow,
+    "detects the usage of trait methods which are ambiguous with traits added to the \
+        prelude in future editions",
+    @future_incompatible = FutureIncompatibleInfo {
+        reference: "issue #85684 <https://github.com/rust-lang/rust/issues/85684>",
+        edition: Some(Edition::Edition2021),
+    };
+}

compiler/rustc_middle/src/mir/mod.rs

@@ -494,6 +494,8 @@ impl<'tcx> Body<'tcx> {
 #[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]
 pub enum Safety {
     Safe,
+    /// Unsafe because of compiler-generated unsafe code, like `await` desugaring
+    BuiltinUnsafe,
     /// Unsafe because of an unsafe fn
     FnUnsafe,
     /// Unsafe because of an `unsafe` block

compiler/rustc_middle/src/thir.rs

@@ -114,6 +114,7 @@ pub struct Adt<'tcx> {
 #[derive(Copy, Clone, Debug, HashStable)]
 pub enum BlockSafety {
     Safe,
+    BuiltinUnsafe,
     ExplicitUnsafe(hir::HirId),
 }
 

compiler/rustc_mir/src/transform/check_unsafety.rs

@@ -321,6 +321,7 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
                 }
                 false
             }
+            Safety::BuiltinUnsafe => true,
             Safety::ExplicitUnsafe(hir_id) => {
                 // mark unsafe block as used if there are any unsafe operations inside
                 if !violations.is_empty() {

compiler/rustc_mir_build/src/build/block.rs

@@ -214,6 +214,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         debug!("update_source_scope_for({:?}, {:?})", span, safety_mode);
         let new_unsafety = match safety_mode {
             BlockSafety::Safe => None,
+            BlockSafety::BuiltinUnsafe => Some(Safety::BuiltinUnsafe),
             BlockSafety::ExplicitUnsafe(hir_id) => {
                 match self.in_scope_unsafe {
                     Safety::Safe => {}

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -29,11 +29,7 @@ struct UnsafetyVisitor<'a, 'tcx> {
 }
 
 impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
-    fn in_safety_context<R>(
-        &mut self,
-        safety_context: SafetyContext,
-        f: impl FnOnce(&mut Self) -> R,
-    ) {
+    fn in_safety_context(&mut self, safety_context: SafetyContext, f: impl FnOnce(&mut Self)) {
         if let (
             SafetyContext::UnsafeBlock { span: enclosing_span, .. },
             SafetyContext::UnsafeBlock { span: block_span, hir_id, .. },
@@ -63,14 +59,14 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
                 );
             }
             self.safety_context = prev_context;
-            return;
         }
     }
 
     fn requires_unsafe(&mut self, span: Span, kind: UnsafeOpKind) {
         let (description, note) = kind.description_and_note();
         let unsafe_op_in_unsafe_fn_allowed = self.unsafe_op_in_unsafe_fn_allowed();
         match self.safety_context {
+            SafetyContext::BuiltinUnsafeBlock => {}
             SafetyContext::UnsafeBlock { ref mut used, .. } => {
                 if !self.body_unsafety.is_unsafe() || !unsafe_op_in_unsafe_fn_allowed {
                     // Mark this block as useful
@@ -142,13 +138,23 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
     }
 
     fn visit_block(&mut self, block: &Block) {
-        if let BlockSafety::ExplicitUnsafe(hir_id) = block.safety_mode {
-            self.in_safety_context(
-                SafetyContext::UnsafeBlock { span: block.span, hir_id, used: false },
-                |this| visit::walk_block(this, block),
-            );
-        } else {
-            visit::walk_block(self, block);
+        match block.safety_mode {
+            // compiler-generated unsafe code should not count towards the usefulness of
+            // an outer unsafe block
+            BlockSafety::BuiltinUnsafe => {
+                self.in_safety_context(SafetyContext::BuiltinUnsafeBlock, |this| {
+                    visit::walk_block(this, block)
+                });
+            }
+            BlockSafety::ExplicitUnsafe(hir_id) => {
+                self.in_safety_context(
+                    SafetyContext::UnsafeBlock { span: block.span, hir_id, used: false },
+                    |this| visit::walk_block(this, block),
+                );
+            }
+            BlockSafety::Safe => {
+                visit::walk_block(self, block);
+            }
         }
     }
 
@@ -250,6 +256,7 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
 #[derive(Clone, Copy)]
 enum SafetyContext {
     Safe,
+    BuiltinUnsafeBlock,
     UnsafeFn,
     UnsafeBlock { span: Span, hir_id: hir::HirId, used: bool },
 }

compiler/rustc_mir_build/src/thir/cx/block.rs

@@ -26,7 +26,12 @@ impl<'tcx> Cx<'tcx> {
             expr: block.expr.map(|expr| self.mirror_expr(expr)),
             safety_mode: match block.rules {
                 hir::BlockCheckMode::DefaultBlock => BlockSafety::Safe,
-                hir::BlockCheckMode::UnsafeBlock(..) => BlockSafety::ExplicitUnsafe(block.hir_id),
+                hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated) => {
+                    BlockSafety::BuiltinUnsafe
+                }
+                hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::UserProvided) => {
+                    BlockSafety::ExplicitUnsafe(block.hir_id)
+                }
             },
         }
     }

compiler/rustc_span/src/symbol.rs

@@ -586,6 +586,7 @@ symbols! {
         from,
         from_desugaring,
         from_generator,
+        from_iter,
         from_method,
         from_output,
         from_residual,
@@ -1238,7 +1239,9 @@ symbols! {
         truncf32,
         truncf64,
         try_blocks,
+        try_from,
         try_from_trait,
+        try_into,
         try_into_trait,
         try_trait_v2,
         tt,

compiler/rustc_typeck/src/astconv/mod.rs

@@ -2418,6 +2418,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 visitor.0,
                 true,
                 hir_ty,
+                "function",
             );
         }
 

compiler/rustc_typeck/src/check/expr.rs

@@ -466,7 +466,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         expr: &'tcx hir::Expr<'tcx>,
     ) -> Ty<'tcx> {
         let tcx = self.tcx;
-        let (res, opt_ty, segs) = self.resolve_ty_and_res_ufcs(qpath, expr.hir_id, expr.span);
+        let (res, opt_ty, segs) =
+            self.resolve_ty_and_res_fully_qualified_call(qpath, expr.hir_id, expr.span);
         let ty = match res {
             Res::Err => {
                 self.set_tainted_by_errors();
@@ -940,7 +941,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // no need to check for bot/err -- callee does that
         let rcvr_t = self.structurally_resolved_type(args[0].span, rcvr_t);
 
-        let method = match self.lookup_method(rcvr_t, segment, span, expr, rcvr) {
+        let method = match self.lookup_method(rcvr_t, segment, span, expr, rcvr, args) {
             Ok(method) => {
                 // We could add a "consider `foo::<params>`" suggestion here, but I wasn't able to
                 // trigger this codepath causing `structuraly_resolved_type` to emit an error.

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -906,13 +906,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
     /// Resolves an associated value path into a base type and associated constant, or method
     /// resolution. The newly resolved definition is written into `type_dependent_defs`.
-    pub fn resolve_ty_and_res_ufcs(
+    pub fn resolve_ty_and_res_fully_qualified_call(
         &self,
         qpath: &'tcx QPath<'tcx>,
         hir_id: hir::HirId,
         span: Span,
     ) -> (Res, Option<Ty<'tcx>>, &'tcx [hir::PathSegment<'tcx>]) {
-        debug!("resolve_ty_and_res_ufcs: qpath={:?} hir_id={:?} span={:?}", qpath, hir_id, span);
+        debug!(
+            "resolve_ty_and_res_fully_qualified_call: qpath={:?} hir_id={:?} span={:?}",
+            qpath, hir_id, span
+        );
         let (ty, qself, item_segment) = match *qpath {
             QPath::Resolved(ref opt_qself, ref path) => {
                 return (
@@ -922,7 +925,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 );
             }
             QPath::TypeRelative(ref qself, ref segment) => (self.to_ty(qself), qself, segment),
-            QPath::LangItem(..) => bug!("`resolve_ty_and_res_ufcs` called on `LangItem`"),
+            QPath::LangItem(..) => {
+                bug!("`resolve_ty_and_res_fully_qualified_call` called on `LangItem`")
+            }
         };
         if let Some(&cached_result) = self.typeck_results.borrow().type_dependent_defs().get(hir_id)
         {
@@ -932,25 +937,27 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             return (def, Some(ty), slice::from_ref(&**item_segment));
         }
         let item_name = item_segment.ident;
-        let result = self.resolve_ufcs(span, item_name, ty, hir_id).or_else(|error| {
-            let result = match error {
-                method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
-                _ => Err(ErrorReported),
-            };
-            if item_name.name != kw::Empty {
-                if let Some(mut e) = self.report_method_error(
-                    span,
-                    ty,
-                    item_name,
-                    SelfSource::QPath(qself),
-                    error,
-                    None,
-                ) {
-                    e.emit();
+        let result = self
+            .resolve_fully_qualified_call(span, item_name, ty, qself.span, hir_id)
+            .or_else(|error| {
+                let result = match error {
+                    method::MethodError::PrivateMatch(kind, def_id, _) => Ok((kind, def_id)),
+                    _ => Err(ErrorReported),
+                };
+                if item_name.name != kw::Empty {
+                    if let Some(mut e) = self.report_method_error(
+                        span,
+                        ty,
+                        item_name,
+                        SelfSource::QPath(qself),
+                        error,
+                        None,
+                    ) {
+                        e.emit();
+                    }
                 }
-            }
-            result
-        });
+                result
+            });
 
         if result.is_ok() {
             self.maybe_lint_bare_trait(qpath, hir_id);