Rollup merge of #113663 - syvb:non_inherited_unsafe_thir, r=cjgillot

Implement "items do not inherit unsafety" note for THIR unsafeck

Implements the "items do not inherit unsafety from separate enclosing items" note from the MIR unsafety checker in the THIR unsafety checker (`-Z thir-unsafeck`) to maintain parity between the two unsafety checkers. The logic to find the separate enclosing item is nearly the same as in the MIR unsafety checker.

Author: matthiaskrgr

compiler/rustc_mir_build/messages.ftl

@@ -312,6 +312,8 @@ mir_build_unreachable_pattern = unreachable pattern
     .label = unreachable pattern
     .catchall_label = matches any value
 
+mir_build_unsafe_not_inherited = items do not inherit unsafety from separate enclosing items
+
 mir_build_unsafe_op_in_unsafe_fn_borrow_of_layout_constrained_field_requires_unsafe =
     borrow of layout constrained field with interior mutability is unsafe and requires unsafe block (error E0133)
     .note = references to fields of layout constrained fields lose the constraints. Coupled with interior mutability, the field can be changed to invalid values

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -91,7 +91,12 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
                 kind.emit_unsafe_op_in_unsafe_fn_lint(self.tcx, self.hir_context, span);
             }
             SafetyContext::Safe => {
-                kind.emit_requires_unsafe_err(self.tcx, span, unsafe_op_in_unsafe_fn_allowed);
+                kind.emit_requires_unsafe_err(
+                    self.tcx,
+                    span,
+                    self.hir_context,
+                    unsafe_op_in_unsafe_fn_allowed,
+                );
             }
         }
     }
@@ -602,98 +607,164 @@ impl UnsafeOpKind {
         &self,
         tcx: TyCtxt<'_>,
         span: Span,
+        hir_context: hir::HirId,
         unsafe_op_in_unsafe_fn_allowed: bool,
     ) {
+        let note_non_inherited = tcx.hir().parent_iter(hir_context).find(|(id, node)| {
+            if let hir::Node::Expr(block) = node
+                && let hir::ExprKind::Block(block, _) = block.kind
+                && let hir::BlockCheckMode::UnsafeBlock(_) = block.rules
+            {
+                true
+            }
+            else if let Some(sig) = tcx.hir().fn_sig_by_hir_id(*id)
+                && sig.header.is_unsafe()
+            {
+                true
+            } else {
+                false
+            }
+        });
+        let unsafe_not_inherited_note = if let Some((id, _)) = note_non_inherited {
+            let span = tcx.hir().span(id);
+            let span = tcx.sess.source_map().guess_head_span(span);
+            Some(UnsafeNotInheritedNote { span })
+        } else {
+            None
+        };
+
         match self {
             CallToUnsafeFunction(Some(did)) if unsafe_op_in_unsafe_fn_allowed => {
                 tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
                     span,
+                    unsafe_not_inherited_note,
                     function: &tcx.def_path_str(*did),
                 });
             }
             CallToUnsafeFunction(Some(did)) => {
                 tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafe {
                     span,
+                    unsafe_not_inherited_note,
                     function: &tcx.def_path_str(*did),
                 });
             }
             CallToUnsafeFunction(None) if unsafe_op_in_unsafe_fn_allowed => {
                 tcx.sess.emit_err(
-                    CallToUnsafeFunctionRequiresUnsafeNamelessUnsafeOpInUnsafeFnAllowed { span },
+                    CallToUnsafeFunctionRequiresUnsafeNamelessUnsafeOpInUnsafeFnAllowed {
+                        span,
+                        unsafe_not_inherited_note,
+                    },
                 );
             }
             CallToUnsafeFunction(None) => {
-                tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafeNameless { span });
+                tcx.sess.emit_err(CallToUnsafeFunctionRequiresUnsafeNameless {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             UseOfInlineAssembly if unsafe_op_in_unsafe_fn_allowed => {
-                tcx.sess
-                    .emit_err(UseOfInlineAssemblyRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+                tcx.sess.emit_err(UseOfInlineAssemblyRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             UseOfInlineAssembly => {
-                tcx.sess.emit_err(UseOfInlineAssemblyRequiresUnsafe { span });
+                tcx.sess.emit_err(UseOfInlineAssemblyRequiresUnsafe {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             InitializingTypeWith if unsafe_op_in_unsafe_fn_allowed => {
-                tcx.sess
-                    .emit_err(InitializingTypeWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+                tcx.sess.emit_err(InitializingTypeWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             InitializingTypeWith => {
-                tcx.sess.emit_err(InitializingTypeWithRequiresUnsafe { span });
+                tcx.sess.emit_err(InitializingTypeWithRequiresUnsafe {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             UseOfMutableStatic if unsafe_op_in_unsafe_fn_allowed => {
-                tcx.sess
-                    .emit_err(UseOfMutableStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+                tcx.sess.emit_err(UseOfMutableStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             UseOfMutableStatic => {
-                tcx.sess.emit_err(UseOfMutableStaticRequiresUnsafe { span });
+                tcx.sess
+                    .emit_err(UseOfMutableStaticRequiresUnsafe { span, unsafe_not_inherited_note });
             }
             UseOfExternStatic if unsafe_op_in_unsafe_fn_allowed => {
-                tcx.sess
-                    .emit_err(UseOfExternStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+                tcx.sess.emit_err(UseOfExternStaticRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             UseOfExternStatic => {
-                tcx.sess.emit_err(UseOfExternStaticRequiresUnsafe { span });
+                tcx.sess
+                    .emit_err(UseOfExternStaticRequiresUnsafe { span, unsafe_not_inherited_note });
             }
             DerefOfRawPointer if unsafe_op_in_unsafe_fn_allowed => {
-                tcx.sess
-                    .emit_err(DerefOfRawPointerRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+                tcx.sess.emit_err(DerefOfRawPointerRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             DerefOfRawPointer => {
-                tcx.sess.emit_err(DerefOfRawPointerRequiresUnsafe { span });
+                tcx.sess
+                    .emit_err(DerefOfRawPointerRequiresUnsafe { span, unsafe_not_inherited_note });
             }
             AccessToUnionField if unsafe_op_in_unsafe_fn_allowed => {
-                tcx.sess
-                    .emit_err(AccessToUnionFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span });
+                tcx.sess.emit_err(AccessToUnionFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             AccessToUnionField => {
-                tcx.sess.emit_err(AccessToUnionFieldRequiresUnsafe { span });
+                tcx.sess
+                    .emit_err(AccessToUnionFieldRequiresUnsafe { span, unsafe_not_inherited_note });
             }
             MutationOfLayoutConstrainedField if unsafe_op_in_unsafe_fn_allowed => {
                 tcx.sess.emit_err(
                     MutationOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
                         span,
+                        unsafe_not_inherited_note,
                     },
                 );
             }
             MutationOfLayoutConstrainedField => {
-                tcx.sess.emit_err(MutationOfLayoutConstrainedFieldRequiresUnsafe { span });
+                tcx.sess.emit_err(MutationOfLayoutConstrainedFieldRequiresUnsafe {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             BorrowOfLayoutConstrainedField if unsafe_op_in_unsafe_fn_allowed => {
                 tcx.sess.emit_err(
-                    BorrowOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed { span },
+                    BorrowOfLayoutConstrainedFieldRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
+                        span,
+                        unsafe_not_inherited_note,
+                    },
                 );
             }
             BorrowOfLayoutConstrainedField => {
-                tcx.sess.emit_err(BorrowOfLayoutConstrainedFieldRequiresUnsafe { span });
+                tcx.sess.emit_err(BorrowOfLayoutConstrainedFieldRequiresUnsafe {
+                    span,
+                    unsafe_not_inherited_note,
+                });
             }
             CallToFunctionWith(did) if unsafe_op_in_unsafe_fn_allowed => {
                 tcx.sess.emit_err(CallToFunctionWithRequiresUnsafeUnsafeOpInUnsafeFnAllowed {
                     span,
+                    unsafe_not_inherited_note,
                     function: &tcx.def_path_str(*did),
                 });
             }
             CallToFunctionWith(did) => {
                 tcx.sess.emit_err(CallToFunctionWithRequiresUnsafe {
                     span,
+                    unsafe_not_inherited_note,
                     function: &tcx.def_path_str(*did),
                 });
             }