2 files changed, 40 insertions, 4 deletions

diff --git a/crates/hir/src/diagnostics.rs b/crates/hir/src/diagnostics.rs
index 2edb53765..e888fc23b 100644
--- a/crates/hir/src/diagnostics.rs
+++ b/crates/hir/src/diagnostics.rs
@@ -301,3 +301,27 @@ impl Diagnostic for BreakOutsideOfLoop {
         self
     }
 }
+
+// Diagnostic: missing-unsafe
+//
+// This diagnostic is triggered if an operation marked as `unsafe` is used outside of an `unsafe` function or block.
+#[derive(Debug)]
+pub struct MissingUnsafe {
+    pub file: HirFileId,
+    pub expr: AstPtr<ast::Expr>,
+}
+
+impl Diagnostic for MissingUnsafe {
+    fn code(&self) -> DiagnosticCode {
+        DiagnosticCode("missing-unsafe")
+    }
+    fn message(&self) -> String {
+        format!("This operation is unsafe and requires an unsafe function or block")
+    }
+    fn display_source(&self) -> InFile<SyntaxNodePtr> {
+        InFile { file_id: self.file, value: self.expr.clone().into() }
+    }
+    fn as_any(&self) -> &(dyn Any + Send + 'static) {
+        self
+    }
+}
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index bce626b03..a21a9da21 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -36,14 +36,14 @@ use std::{iter, sync::Arc};
 use arrayvec::ArrayVec;
 use base_db::{CrateDisplayName, CrateId, Edition, FileId};
 use diagnostics::{
-    BreakOutsideOfLoop, InactiveCode, MacroError, NoSuchField, UnimplementedBuiltinMacro,
-    UnresolvedExternCrate, UnresolvedImport, UnresolvedMacroCall, UnresolvedModule,
-    UnresolvedProcMacro,
+    BreakOutsideOfLoop, InactiveCode, MacroError, MissingUnsafe, NoSuchField,
+    UnimplementedBuiltinMacro, UnresolvedExternCrate, UnresolvedImport, UnresolvedMacroCall,
+    UnresolvedModule, UnresolvedProcMacro,
 };
 use either::Either;
 use hir_def::{
     adt::{ReprKind, VariantData},
-    body::BodyDiagnostic,
+    body::{BodyDiagnostic, SyntheticSyntax},
     expr::{BindingAnnotation, LabelId, Pat, PatId},
     item_tree::ItemTreeNode,
     lang_item::LangItemTarget,
@@ -1060,6 +1060,18 @@ impl Function {
             }
         }
 
+        for expr in hir_ty::diagnostics::missing_unsafe(db, self.id.into()) {
+            match source_map.as_ref().expr_syntax(expr) {
+                Ok(in_file) => {
+                    sink.push(MissingUnsafe { file: in_file.file_id, expr: in_file.value })
+                }
+                Err(SyntheticSyntax) => {
+                    // FIXME: The `expr` was desugared, report or assert that
+                    // this dosen't happen.
+                }
+            }
+        }
+
         hir_ty::diagnostics::validate_module_item(db, krate, self.id.into(), sink);
         hir_ty::diagnostics::validate_body(db, self.id.into(), sink);
     }