Rollup of 8 pull requests

compiler/rustc_hir_analysis/src/check/check.rs

@@ -380,7 +380,6 @@ fn check_struct(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     let def = tcx.adt_def(def_id);
     let span = tcx.def_span(def_id);
     def.destructor(tcx); // force the destructor to be evaluated
-    let _ = tcx.representability(def_id);
 
     if def.repr().simd() {
         check_simd(tcx, span, def_id);
@@ -394,7 +393,6 @@ fn check_union(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     let def = tcx.adt_def(def_id);
     let span = tcx.def_span(def_id);
     def.destructor(tcx); // force the destructor to be evaluated
-    let _ = tcx.representability(def_id);
     check_transparent(tcx, span, def);
     check_union_fields(tcx, span, def_id);
     check_packed(tcx, span, def);
@@ -1489,7 +1487,6 @@ fn check_enum<'tcx>(tcx: TyCtxt<'tcx>, vs: &'tcx [hir::Variant<'tcx>], def_id: L
 
     detect_discriminant_duplicate(tcx, def.discriminants(tcx).collect(), vs, sp);
 
-    let _ = tcx.representability(def_id);
     check_transparent(tcx, sp, def);
 }
 

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1041,6 +1041,8 @@ fn check_type_defn<'tcx, F>(
 ) where
     F: FnMut(&WfCheckingCtxt<'_, 'tcx>) -> Vec<AdtVariant<'tcx>>,
 {
+    let _ = tcx.representability(item.def_id.def_id);
+
     enter_wf_checking_ctxt(tcx, item.span, item.def_id.def_id, |wfcx| {
         let variants = lookup_fields(wfcx);
         let packed = tcx.adt_def(item.def_id).repr().packed();

compiler/rustc_interface/src/interface.rs

@@ -276,67 +276,61 @@ pub struct Config {
     pub registry: Registry,
 }
 
-pub fn create_compiler_and_run<R>(config: Config, f: impl FnOnce(&Compiler) -> R) -> R {
-    crate::callbacks::setup_callbacks();
-
-    let registry = &config.registry;
-    let (mut sess, codegen_backend) = util::create_session(
-        config.opts,
-        config.crate_cfg,
-        config.crate_check_cfg,
-        config.diagnostic_output,
-        config.file_loader,
-        config.input_path.clone(),
-        config.lint_caps,
-        config.make_codegen_backend,
-        registry.clone(),
-    );
-
-    if let Some(parse_sess_created) = config.parse_sess_created {
-        parse_sess_created(
-            &mut Lrc::get_mut(&mut sess)
-                .expect("create_session() should never share the returned session")
-                .parse_sess,
-        );
-    }
-
-    let temps_dir = sess.opts.unstable_opts.temps_dir.as_ref().map(|o| PathBuf::from(&o));
-
-    let compiler = Compiler {
-        sess,
-        codegen_backend,
-        input: config.input,
-        input_path: config.input_path,
-        output_dir: config.output_dir,
-        output_file: config.output_file,
-        temps_dir,
-        register_lints: config.register_lints,
-        override_queries: config.override_queries,
-    };
-
-    rustc_span::with_source_map(compiler.sess.parse_sess.clone_source_map(), move || {
-        let r = {
-            let _sess_abort_error = OnDrop(|| {
-                compiler.sess.finish_diagnostics(registry);
-            });
-
-            f(&compiler)
-        };
-
-        let prof = compiler.sess.prof.clone();
-        prof.generic_activity("drop_compiler").run(move || drop(compiler));
-        r
-    })
-}
-
 // JUSTIFICATION: before session exists, only config
 #[allow(rustc::bad_opt_access)]
 pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Send) -> R {
     trace!("run_compiler");
     util::run_in_thread_pool_with_globals(
         config.opts.edition,
         config.opts.unstable_opts.threads,
-        || create_compiler_and_run(config, f),
+        || {
+            crate::callbacks::setup_callbacks();
+
+            let registry = &config.registry;
+            let (mut sess, codegen_backend) = util::create_session(
+                config.opts,
+                config.crate_cfg,
+                config.crate_check_cfg,
+                config.diagnostic_output,
+                config.file_loader,
+                config.input_path.clone(),
+                config.lint_caps,
+                config.make_codegen_backend,
+                registry.clone(),
+            );
+
+            if let Some(parse_sess_created) = config.parse_sess_created {
+                parse_sess_created(&mut sess.parse_sess);
+            }
+
+            let temps_dir = sess.opts.unstable_opts.temps_dir.as_ref().map(|o| PathBuf::from(&o));
+
+            let compiler = Compiler {
+                sess: Lrc::new(sess),
+                codegen_backend: Lrc::new(codegen_backend),
+                input: config.input,
+                input_path: config.input_path,
+                output_dir: config.output_dir,
+                output_file: config.output_file,
+                temps_dir,
+                register_lints: config.register_lints,
+                override_queries: config.override_queries,
+            };
+
+            rustc_span::with_source_map(compiler.sess.parse_sess.clone_source_map(), move || {
+                let r = {
+                    let _sess_abort_error = OnDrop(|| {
+                        compiler.sess.finish_diagnostics(registry);
+                    });
+
+                    f(&compiler)
+                };
+
+                let prof = compiler.sess.prof.clone();
+                prof.generic_activity("drop_compiler").run(move || drop(compiler));
+                r
+            })
+        },
     )
 }
 

compiler/rustc_interface/src/util.rs

@@ -5,7 +5,6 @@ use rustc_codegen_ssa::traits::CodegenBackend;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 #[cfg(parallel_compiler)]
 use rustc_data_structures::jobserver;
-use rustc_data_structures::sync::Lrc;
 use rustc_errors::registry::Registry;
 #[cfg(parallel_compiler)]
 use rustc_middle::ty::tls;
@@ -73,7 +72,7 @@ pub fn create_session(
         Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>,
     >,
     descriptions: Registry,
-) -> (Lrc<Session>, Lrc<Box<dyn CodegenBackend>>) {
+) -> (Session, Box<dyn CodegenBackend>) {
     let codegen_backend = if let Some(make_codegen_backend) = make_codegen_backend {
         make_codegen_backend(&sopts)
     } else {
@@ -121,7 +120,7 @@ pub fn create_session(
     sess.parse_sess.config = cfg;
     sess.parse_sess.check_config = check_cfg;
 
-    (Lrc::new(sess), Lrc::new(codegen_backend))
+    (sess, codegen_backend)
 }
 
 const STACK_SIZE: usize = 8 * 1024 * 1024;
@@ -132,33 +131,31 @@ fn get_stack_size() -> Option<usize> {
     env::var_os("RUST_MIN_STACK").is_none().then_some(STACK_SIZE)
 }
 
-/// Like a `thread::Builder::spawn` followed by a `join()`, but avoids the need
-/// for `'static` bounds.
 #[cfg(not(parallel_compiler))]
-fn scoped_thread<F: FnOnce() -> R + Send, R: Send>(cfg: thread::Builder, f: F) -> R {
-    // SAFETY: join() is called immediately, so any closure captures are still
-    // alive.
-    match unsafe { cfg.spawn_unchecked(f) }.unwrap().join() {
-        Ok(v) => v,
-        Err(e) => panic::resume_unwind(e),
-    }
-}
-
-#[cfg(not(parallel_compiler))]
-pub fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
+pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
     edition: Edition,
     _threads: usize,
     f: F,
 ) -> R {
-    let mut cfg = thread::Builder::new().name("rustc".to_string());
-
-    if let Some(size) = get_stack_size() {
-        cfg = cfg.stack_size(size);
-    }
+    // The thread pool is a single thread in the non-parallel compiler.
+    thread::scope(|s| {
+        let mut builder = thread::Builder::new().name("rustc".to_string());
+        if let Some(size) = get_stack_size() {
+            builder = builder.stack_size(size);
+        }
 
-    let main_handler = move || rustc_span::create_session_globals_then(edition, f);
+        // `unwrap` is ok here because `spawn_scoped` only panics if the thread
+        // name contains null bytes.
+        let r = builder
+            .spawn_scoped(s, move || rustc_span::create_session_globals_then(edition, f))
+            .unwrap()
+            .join();
 
-    scoped_thread(cfg, main_handler)
+        match r {
+            Ok(v) => v,
+            Err(e) => panic::resume_unwind(e),
+        }
+    })
 }
 
 /// Creates a new thread and forwards information in thread locals to it.
@@ -177,7 +174,7 @@ unsafe fn handle_deadlock() {
 }
 
 #[cfg(parallel_compiler)]
-pub fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
+pub(crate) fn run_in_thread_pool_with_globals<F: FnOnce() -> R + Send, R: Send>(
     edition: Edition,
     threads: usize,
     f: F,

compiler/rustc_middle/src/query/mod.rs

@@ -613,16 +613,8 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    // The cycle error here should be reported as an error by `check_representable`.
-    // We consider the type as Sized in the meanwhile to avoid
-    // further errors (done in impl Value for AdtSizedConstraint).
-    // Use `cycle_delay_bug` to delay the cycle error here to be emitted later
-    // in case we accidentally otherwise don't emit an error.
-    query adt_sized_constraint(
-        key: DefId
-    ) -> AdtSizedConstraint<'tcx> {
+    query adt_sized_constraint(key: DefId) -> &'tcx [Ty<'tcx>] {
         desc { |tcx| "computing `Sized` constraints for `{}`", tcx.def_path_str(key) }
-        cycle_delay_bug
     }
 
     query adt_dtorck_constraint(

compiler/rustc_middle/src/ty/adt.rs

@@ -26,9 +26,6 @@ use super::{
     Destructor, FieldDef, GenericPredicates, ReprOptions, Ty, TyCtxt, VariantDef, VariantDiscr,
 };
 
-#[derive(Copy, Clone, HashStable, Debug)]
-pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
-
 bitflags! {
     #[derive(HashStable, TyEncodable, TyDecodable)]
     pub struct AdtFlags: u32 {
@@ -563,7 +560,7 @@ impl<'tcx> AdtDef<'tcx> {
     /// Due to normalization being eager, this applies even if
     /// the associated type is behind a pointer (e.g., issue #31299).
     pub fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> ty::EarlyBinder<&'tcx [Ty<'tcx>]> {
-        ty::EarlyBinder(tcx.adt_sized_constraint(self.did()).0)
+        ty::EarlyBinder(tcx.adt_sized_constraint(self.did()))
     }
 }
 

compiler/rustc_middle/src/ty/query.rs

@@ -32,7 +32,7 @@ use crate::ty::layout::TyAndLayout;
 use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::util::AlwaysRequiresDrop;
 use crate::ty::GeneratorDiagnosticData;
-use crate::ty::{self, AdtSizedConstraint, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt};
+use crate::ty::{self, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt};
 use rustc_ast as ast;
 use rustc_ast::expand::allocator::AllocatorKind;
 use rustc_attr as attr;

compiler/rustc_middle/src/values.rs

@@ -3,7 +3,7 @@ use rustc_errors::{pluralize, struct_span_err, Applicability, MultiSpan};
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_middle::ty::Representability;
-use rustc_middle::ty::{self, AdtSizedConstraint, DefIdTree, Ty, TyCtxt};
+use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt};
 use rustc_query_system::query::QueryInfo;
 use rustc_query_system::Value;
 use rustc_span::def_id::LocalDefId;
@@ -31,18 +31,6 @@ impl<'tcx> Value<TyCtxt<'tcx>> for ty::SymbolName<'_> {
     }
 }
 
-impl<'tcx> Value<TyCtxt<'tcx>> for AdtSizedConstraint<'_> {
-    fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> Self {
-        // SAFETY: This is never called when `Self` is not `AdtSizedConstraint<'tcx>`.
-        // FIXME: Represent the above fact in the trait system somehow.
-        unsafe {
-            std::mem::transmute::<AdtSizedConstraint<'tcx>, AdtSizedConstraint<'_>>(
-                AdtSizedConstraint(tcx.intern_type_list(&[tcx.ty_error()])),
-            )
-        }
-    }
-}
-
 impl<'tcx> Value<TyCtxt<'tcx>> for ty::Binder<'_, ty::FnSig<'_>> {
     fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> Self {
         let err = tcx.ty_error();

compiler/rustc_ty_utils/src/ty.rs

@@ -85,9 +85,13 @@ fn impl_defaultness(tcx: TyCtxt<'_>, def_id: DefId) -> hir::Defaultness {
 ///     - a type parameter or projection whose Sizedness can't be known
 ///     - a tuple of type parameters or projections, if there are multiple
 ///       such.
-///     - an Error, if a type contained itself. The representability
-///       check should catch this case.
-fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AdtSizedConstraint<'_> {
+///     - an Error, if a type is infinitely sized
+fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> &[Ty<'_>] {
+    if let Some(def_id) = def_id.as_local() {
+        if matches!(tcx.representability(def_id), ty::Representability::Infinite) {
+            return tcx.intern_type_list(&[tcx.ty_error()]);
+        }
+    }
     let def = tcx.adt_def(def_id);
 
     let result = tcx.mk_type_list(
@@ -99,7 +103,7 @@ fn adt_sized_constraint(tcx: TyCtxt<'_>, def_id: DefId) -> ty::AdtSizedConstrain
 
     debug!("adt_sized_constraint: {:?} => {:?}", def, result);
 
-    ty::AdtSizedConstraint(result)
+    result
 }
 
 /// See `ParamEnv` struct definition for details.

library/panic_unwind/src/emcc.rs

@@ -47,7 +47,12 @@ static EXCEPTION_TYPE_INFO: TypeInfo = TypeInfo {
     name: b"rust_panic\0".as_ptr(),
 };
 
+// NOTE(nbdd0121): The `canary` field will be part of stable ABI after `c_unwind` stabilization.
+#[repr(C)]
 struct Exception {
+    // See `gcc.rs` on why this is present. We already have a static here so just use it.
+    canary: *const TypeInfo,
+
     // This is necessary because C++ code can capture our exception with
     // std::exception_ptr and rethrow it multiple times, possibly even in
     // another thread.
@@ -70,16 +75,21 @@ pub unsafe fn cleanup(ptr: *mut u8) -> Box<dyn Any + Send> {
     let catch_data = &*(ptr as *mut CatchData);
 
     let adjusted_ptr = __cxa_begin_catch(catch_data.ptr as *mut libc::c_void) as *mut Exception;
-    let out = if catch_data.is_rust_panic {
-        let was_caught = (*adjusted_ptr).caught.swap(true, Ordering::SeqCst);
-        if was_caught {
-            // Since cleanup() isn't allowed to panic, we just abort instead.
-            intrinsics::abort();
-        }
-        (*adjusted_ptr).data.take().unwrap()
-    } else {
+    if !catch_data.is_rust_panic {
         super::__rust_foreign_exception();
-    };
+    }
+
+    let canary = ptr::addr_of!((*adjusted_ptr).canary).read();
+    if !ptr::eq(canary, &EXCEPTION_TYPE_INFO) {
+        super::__rust_foreign_exception();
+    }
+
+    let was_caught = (*adjusted_ptr).caught.swap(true, Ordering::SeqCst);
+    if was_caught {
+        // Since cleanup() isn't allowed to panic, we just abort instead.
+        intrinsics::abort();
+    }
+    let out = (*adjusted_ptr).data.take().unwrap();
     __cxa_end_catch();
     out
 }
@@ -90,7 +100,14 @@ pub unsafe fn panic(data: Box<dyn Any + Send>) -> u32 {
     if exception.is_null() {
         return uw::_URC_FATAL_PHASE1_ERROR as u32;
     }
-    ptr::write(exception, Exception { caught: AtomicBool::new(false), data: Some(data) });
+    ptr::write(
+        exception,
+        Exception {
+            canary: &EXCEPTION_TYPE_INFO,
+            caught: AtomicBool::new(false),
+            data: Some(data),
+        },
+    );
     __cxa_throw(exception as *mut _, &EXCEPTION_TYPE_INFO, exception_cleanup);
 }