Rollup of 6 pull requests

compiler/rustc_borrowck/src/constraints/graph.rs

@@ -156,6 +156,7 @@ impl<'s, 'tcx, D: ConstraintGraphDirecton> Iterator for Edges<'s, 'tcx, D> {
                 sup: self.static_region,
                 sub: next_static_idx.into(),
                 locations: Locations::All(DUMMY_SP),
+                span: DUMMY_SP,
                 category: ConstraintCategory::Internal,
                 variance_info: VarianceDiagInfo::default(),
             })

compiler/rustc_borrowck/src/constraints/mod.rs

@@ -2,6 +2,7 @@ use rustc_data_structures::graph::scc::Sccs;
 use rustc_index::vec::IndexVec;
 use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::{RegionVid, VarianceDiagInfo};
+use rustc_span::Span;
 use std::fmt;
 use std::ops::Index;
 
@@ -87,6 +88,12 @@ pub struct OutlivesConstraint<'tcx> {
     /// Where did this constraint arise?
     pub locations: Locations,
 
+    /// The `Span` associated with the creation of this constraint.
+    /// This should be used in preference to obtaining the span from
+    /// `locations`, since the `locations` may give a poor span
+    /// in some cases (e.g. converting a constraint from a promoted).
+    pub span: Span,
+
     /// What caused this constraint?
     pub category: ConstraintCategory,
 

compiler/rustc_borrowck/src/region_infer/dump_mir.rs

@@ -74,14 +74,18 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let mut constraints: Vec<_> = self.constraints.outlives().iter().collect();
         constraints.sort_by_key(|c| (c.sup, c.sub));
         for constraint in &constraints {
-            let OutlivesConstraint { sup, sub, locations, category, variance_info: _ } = constraint;
+            let OutlivesConstraint { sup, sub, locations, category, span, variance_info: _ } =
+                constraint;
             let (name, arg) = match locations {
                 Locations::All(span) => {
                     ("All", tcx.sess.source_map().span_to_embeddable_string(*span))
                 }
                 Locations::Single(loc) => ("Single", format!("{:?}", loc)),
             };
-            with_msg(&format!("{:?}: {:?} due to {:?} at {}({})", sup, sub, category, name, arg))?;
+            with_msg(&format!(
+                "{:?}: {:?} due to {:?} at {}({}) ({:?}",
+                sup, sub, category, name, arg, span
+            ))?;
         }
 
         Ok(())

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -1733,7 +1733,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
 
     crate fn retrieve_closure_constraint_info(
         &self,
-        body: &Body<'tcx>,
+        _body: &Body<'tcx>,
         constraint: &OutlivesConstraint<'tcx>,
     ) -> BlameConstraint<'tcx> {
         let loc = match constraint.locations {
@@ -1760,7 +1760,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
             .unwrap_or(BlameConstraint {
                 category: constraint.category,
                 from_closure: false,
-                cause: ObligationCause::dummy_with_span(body.source_info(loc).span),
+                cause: ObligationCause::dummy_with_span(constraint.span),
                 variance_info: constraint.variance_info,
             })
     }
@@ -1869,6 +1869,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                     sup: r,
                     sub: constraint.min_choice,
                     locations: Locations::All(p_c.definition_span),
+                    span: p_c.definition_span,
                     category: ConstraintCategory::OpaqueType,
                     variance_info: ty::VarianceDiagInfo::default(),
                 };
@@ -2017,7 +2018,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
                         category: constraint.category,
                         from_closure: false,
                         cause: ObligationCause::new(
-                            constraint.locations.span(body),
+                            constraint.span,
                             CRATE_HIR_ID,
                             cause_code.clone(),
                         ),

compiler/rustc_borrowck/src/type_check/constraint_conversion.rs

@@ -8,7 +8,7 @@ use rustc_middle::mir::ConstraintCategory;
 use rustc_middle::ty::subst::GenericArgKind;
 use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::{self, TyCtxt};
-use rustc_span::DUMMY_SP;
+use rustc_span::{Span, DUMMY_SP};
 
 use crate::{
     constraints::OutlivesConstraint,
@@ -26,6 +26,7 @@ crate struct ConstraintConversion<'a, 'tcx> {
     implicit_region_bound: Option<ty::Region<'tcx>>,
     param_env: ty::ParamEnv<'tcx>,
     locations: Locations,
+    span: Span,
     category: ConstraintCategory,
     constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
 }
@@ -38,6 +39,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         implicit_region_bound: Option<ty::Region<'tcx>>,
         param_env: ty::ParamEnv<'tcx>,
         locations: Locations,
+        span: Span,
         category: ConstraintCategory,
         constraints: &'a mut MirTypeckRegionConstraints<'tcx>,
     ) -> Self {
@@ -49,6 +51,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
             implicit_region_bound,
             param_env,
             locations,
+            span,
             category,
             constraints,
         }
@@ -153,6 +156,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
         self.constraints.outlives_constraints.push(OutlivesConstraint {
             locations: self.locations,
             category: self.category,
+            span: self.span,
             sub,
             sup,
             variance_info: ty::VarianceDiagInfo::default(),

compiler/rustc_borrowck/src/type_check/free_region_relations.rs

@@ -316,6 +316,7 @@ impl<'tcx> UniversalRegionRelationsBuilder<'_, 'tcx> {
                 self.implicit_region_bound,
                 self.param_env,
                 Locations::All(DUMMY_SP),
+                DUMMY_SP,
                 ConstraintCategory::Internal,
                 &mut self.constraints,
             )

compiler/rustc_borrowck/src/type_check/input_output.rs

@@ -235,6 +235,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                 Some(self.implicit_region_bound),
                 self.param_env,
                 Locations::All(DUMMY_SP),
+                DUMMY_SP,
                 ConstraintCategory::Internal,
                 &mut self.borrowck_context.constraints,
             )

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -1141,6 +1141,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
             Some(self.implicit_region_bound),
             self.param_env,
             locations,
+            locations.span(self.body),
             category,
             &mut self.borrowck_context.constraints,
         )
@@ -2401,6 +2402,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                                 sup: ref_region.to_region_vid(),
                                 sub: borrow_region.to_region_vid(),
                                 locations: location.to_locations(),
+                                span: location.to_locations().span(body),
                                 category,
                                 variance_info: ty::VarianceDiagInfo::default(),
                             });

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -116,6 +116,7 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx>
                 sup,
                 sub,
                 locations: self.locations,
+                span: self.locations.span(self.type_checker.body),
                 category: self.category,
                 variance_info: info,
             },

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -679,7 +679,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         return_place: Option<&PlaceTy<'tcx, M::PointerTag>>,
         return_to_block: StackPopCleanup,
     ) -> InterpResult<'tcx> {
-        debug!("body: {:#?}", body);
+        trace!("body: {:#?}", body);
         // first push a stack frame so we have access to the local substs
         let pre_frame = Frame {
             body,
@@ -836,7 +836,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             return Ok(());
         }
 
-        debug!("locals: {:#?}", frame.locals);
+        trace!("locals: {:#?}", frame.locals);
 
         // Cleanup: deallocate all locals that are backed by an allocation.
         for local in &frame.locals {

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -870,9 +870,17 @@ impl<'tcx, 'a, Tag: Provenance, Extra> AllocRefMut<'a, 'tcx, Tag, Extra> {
         range: AllocRange,
         val: ScalarMaybeUninit<Tag>,
     ) -> InterpResult<'tcx> {
+        let range = self.range.subrange(range);
+        debug!(
+            "write_scalar in {} at {:#x}, size {}: {:?}",
+            self.alloc_id,
+            range.start.bytes(),
+            range.size.bytes(),
+            val
+        );
         Ok(self
             .alloc
-            .write_scalar(&self.tcx, self.range.subrange(range), val)
+            .write_scalar(&self.tcx, range, val)
             .map_err(|e| e.to_interp_error(self.alloc_id))?)
     }
 
@@ -895,10 +903,19 @@ impl<'tcx, 'a, Tag: Provenance, Extra> AllocRefMut<'a, 'tcx, Tag, Extra> {
 
 impl<'tcx, 'a, Tag: Provenance, Extra> AllocRef<'a, 'tcx, Tag, Extra> {
     pub fn read_scalar(&self, range: AllocRange) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> {
-        Ok(self
+        let range = self.range.subrange(range);
+        let res = self
             .alloc
-            .read_scalar(&self.tcx, self.range.subrange(range))
-            .map_err(|e| e.to_interp_error(self.alloc_id))?)
+            .read_scalar(&self.tcx, range)
+            .map_err(|e| e.to_interp_error(self.alloc_id))?;
+        debug!(
+            "read_scalar in {} at {:#x}, size {}: {:?}",
+            self.alloc_id,
+            range.start.bytes(),
+            range.size.bytes(),
+            res
+        );
+        Ok(res)
     }
 
     pub fn read_ptr_sized(&self, offset: Size) -> InterpResult<'tcx, ScalarMaybeUninit<Tag>> {

compiler/rustc_middle/src/mir/interpret/allocation.rs

@@ -515,6 +515,9 @@ impl<Tag: Copy, Extra> Allocation<Tag, Extra> {
             if Tag::ERR_ON_PARTIAL_PTR_OVERWRITE {
                 return Err(AllocError::PartialPointerOverwrite(first));
             }
+            warn!(
+                "Partial pointer overwrite! De-initializing memory at offsets {first:?}..{start:?}."
+            );
             self.init_mask.set_range(first, start, false);
         }
         if last > end {
@@ -523,10 +526,15 @@ impl<Tag: Copy, Extra> Allocation<Tag, Extra> {
                     last - cx.data_layout().pointer_size,
                 ));
             }
+            warn!(
+                "Partial pointer overwrite! De-initializing memory at offsets {end:?}..{last:?}."
+            );
             self.init_mask.set_range(end, last, false);
         }
 
         // Forget all the relocations.
+        // Since relocations do not overlap, we know that removing until `last` (exclusive) is fine,
+        // i.e., this will not remove any other relocations just after the ones we care about.
         self.relocations.0.remove_range(first..last);
 
         Ok(())

compiler/rustc_mir_build/src/build/expr/into.rs

@@ -255,10 +255,15 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         func: fun,
                         args,
                         cleanup: None,
-                        // FIXME(varkor): replace this with an uninhabitedness-based check.
-                        // This requires getting access to the current module to call
-                        // `tcx.is_ty_uninhabited_from`, which is currently tricky to do.
-                        destination: if expr.ty.is_never() {
+                        // The presence or absence of a return edge affects control-flow sensitive
+                        // MIR checks and ultimately whether code is accepted or not. We can only
+                        // omit the return edge if a return type is visibly uninhabited to a module
+                        // that makes the call.
+                        destination: if this.tcx.is_ty_uninhabited_from(
+                            this.parent_module,
+                            expr.ty,
+                            this.param_env,
+                        ) {
                             None
                         } else {
                             Some((destination, success))

compiler/rustc_mir_build/src/build/mod.rs

@@ -350,6 +350,7 @@ struct Builder<'a, 'tcx> {
 
     def_id: DefId,
     hir_id: hir::HirId,
+    parent_module: DefId,
     check_overflow: bool,
     fn_span: Span,
     arg_count: usize,
@@ -807,15 +808,17 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         );
 
         let lint_level = LintLevel::Explicit(hir_id);
+        let param_env = tcx.param_env(def.did);
         let mut builder = Builder {
             thir,
             tcx,
             infcx,
             typeck_results: tcx.typeck_opt_const_arg(def),
             region_scope_tree: tcx.region_scope_tree(def.did),
-            param_env: tcx.param_env(def.did),
+            param_env,
             def_id: def.did.to_def_id(),
             hir_id,
+            parent_module: tcx.parent_module(hir_id).to_def_id(),
             check_overflow,
             cfg: CFG { basic_blocks: IndexVec::new() },
             fn_span: span,

library/std/src/sys/unix/weak.rs

@@ -25,7 +25,8 @@
 use crate::ffi::CStr;
 use crate::marker::PhantomData;
 use crate::mem;
-use crate::sync::atomic::{self, AtomicUsize, Ordering};
+use crate::ptr;
+use crate::sync::atomic::{self, AtomicPtr, Ordering};
 
 // We can use true weak linkage on ELF targets.
 #[cfg(not(any(target_os = "macos", target_os = "ios")))]
@@ -83,25 +84,25 @@ pub(crate) macro dlsym {
 }
 pub(crate) struct DlsymWeak<F> {
     name: &'static str,
-    addr: AtomicUsize,
+    func: AtomicPtr<libc::c_void>,
     _marker: PhantomData<F>,
 }
 
 impl<F> DlsymWeak<F> {
     pub(crate) const fn new(name: &'static str) -> Self {
-        DlsymWeak { name, addr: AtomicUsize::new(1), _marker: PhantomData }
+        DlsymWeak { name, func: AtomicPtr::new(ptr::invalid_mut(1)), _marker: PhantomData }
     }
 
     #[inline]
     pub(crate) fn get(&self) -> Option<F> {
         unsafe {
             // Relaxed is fine here because we fence before reading through the
             // pointer (see the comment below).
-            match self.addr.load(Ordering::Relaxed) {
-                1 => self.initialize(),
-                0 => None,
-                addr => {
-                    let func = mem::transmute_copy::<usize, F>(&addr);
+            match self.func.load(Ordering::Relaxed) {
+                func if func.addr() == 1 => self.initialize(),
+                func if func.is_null() => None,
+                func => {
+                    let func = mem::transmute_copy::<*mut libc::c_void, F>(&func);
                     // The caller is presumably going to read through this value
                     // (by calling the function we've dlsymed). This means we'd
                     // need to have loaded it with at least C11's consume
@@ -129,25 +130,22 @@ impl<F> DlsymWeak<F> {
     // Cold because it should only happen during first-time initialization.
     #[cold]
     unsafe fn initialize(&self) -> Option<F> {
-        assert_eq!(mem::size_of::<F>(), mem::size_of::<usize>());
+        assert_eq!(mem::size_of::<F>(), mem::size_of::<*mut libc::c_void>());
 
         let val = fetch(self.name);
         // This synchronizes with the acquire fence in `get`.
-        self.addr.store(val, Ordering::Release);
+        self.func.store(val, Ordering::Release);
 
-        match val {
-            0 => None,
-            addr => Some(mem::transmute_copy::<usize, F>(&addr)),
-        }
+        if val.is_null() { None } else { Some(mem::transmute_copy::<*mut libc::c_void, F>(&val)) }
     }
 }
 
-unsafe fn fetch(name: &str) -> usize {
+unsafe fn fetch(name: &str) -> *mut libc::c_void {
     let name = match CStr::from_bytes_with_nul(name.as_bytes()) {
         Ok(cstr) => cstr,
-        Err(..) => return 0,
+        Err(..) => return ptr::null_mut(),
     };
-    libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr()) as usize
+    libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr())
 }
 
 #[cfg(not(any(target_os = "linux", target_os = "android")))]