From 42c2364325d18b14b977ab1997e8911cb9e4d1fa Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Thu, 18 Jul 2024 18:02:09 -0400
Subject: [PATCH] Don't allow unsafe statics outside of extern blocks

---
 compiler/rustc_ast_passes/messages.ftl           |  3 +++
 compiler/rustc_ast_passes/src/ast_validation.rs  | 16 +++++++++++-----
 compiler/rustc_ast_passes/src/errors.rs          |  7 +++++++
 .../rust-2024/safe-outside-extern.gated.stderr   |  8 ++++++++
 tests/ui/rust-2024/safe-outside-extern.rs        |  9 +++++++++
 .../rust-2024/safe-outside-extern.ungated.stderr |  8 ++++++++
 6 files changed, 46 insertions(+), 5 deletions(-)
 create mode 100644 tests/ui/rust-2024/safe-outside-extern.gated.stderr
 create mode 100644 tests/ui/rust-2024/safe-outside-extern.rs
 create mode 100644 tests/ui/rust-2024/safe-outside-extern.ungated.stderr

diff --git a/compiler/rustc_ast_passes/messages.ftl b/compiler/rustc_ast_passes/messages.ftl
index 9a8689e27c068..8291d315f61a7 100644
--- a/compiler/rustc_ast_passes/messages.ftl
+++ b/compiler/rustc_ast_passes/messages.ftl
@@ -264,6 +264,9 @@ ast_passes_unsafe_negative_impl = negative impls cannot be unsafe
     .negative = negative because of this
     .unsafe = unsafe because of this
 
+ast_passes_unsafe_static =
+    static items cannot be declared with `unsafe` safety qualifier outside of `extern` block
+
 ast_passes_visibility_not_permitted =
     visibility qualifiers are not permitted here
     .enum_variant = enum variants and their fields always share the visibility of the enum they are in
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
index 0fbb288cc968c..f367df40e82a1 100644
--- a/compiler/rustc_ast_passes/src/ast_validation.rs
+++ b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -1161,11 +1161,17 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                     });
                 }
             }
-            ItemKind::Static(box StaticItem { expr: None, .. }) => {
-                self.dcx().emit_err(errors::StaticWithoutBody {
-                    span: item.span,
-                    replace_span: self.ending_semi_or_hi(item.span),
-                });
+            ItemKind::Static(box StaticItem { expr, safety, .. }) => {
+                if matches!(safety, Safety::Unsafe(_)) {
+                    self.dcx().emit_err(errors::UnsafeStatic { span: item.span });
+                }
+
+                if expr.is_none() {
+                    self.dcx().emit_err(errors::StaticWithoutBody {
+                        span: item.span,
+                        replace_span: self.ending_semi_or_hi(item.span),
+                    });
+                }
             }
             ItemKind::TyAlias(
                 ty_alias @ box TyAlias { defaultness, bounds, where_clauses, ty, .. },
diff --git a/compiler/rustc_ast_passes/src/errors.rs b/compiler/rustc_ast_passes/src/errors.rs
index 260c182bd9e49..a51595a611bb1 100644
--- a/compiler/rustc_ast_passes/src/errors.rs
+++ b/compiler/rustc_ast_passes/src/errors.rs
@@ -225,6 +225,13 @@ pub struct InvalidSafetyOnExtern {
     pub block: Span,
 }
 
+#[derive(Diagnostic)]
+#[diag(ast_passes_unsafe_static)]
+pub struct UnsafeStatic {
+    #[primary_span]
+    pub span: Span,
+}
+
 #[derive(Diagnostic)]
 #[diag(ast_passes_bound_in_context)]
 pub struct BoundInContext<'a> {
diff --git a/tests/ui/rust-2024/safe-outside-extern.gated.stderr b/tests/ui/rust-2024/safe-outside-extern.gated.stderr
new file mode 100644
index 0000000000000..a81f8382859d0
--- /dev/null
+++ b/tests/ui/rust-2024/safe-outside-extern.gated.stderr
@@ -0,0 +1,8 @@
+error: static items cannot be declared with `unsafe` safety qualifier outside of `extern` block
+  --> $DIR/safe-outside-extern.rs:6:1
+   |
+LL | unsafe static LOL: u8 = 0;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
diff --git a/tests/ui/rust-2024/safe-outside-extern.rs b/tests/ui/rust-2024/safe-outside-extern.rs
new file mode 100644
index 0000000000000..137331e9d3853
--- /dev/null
+++ b/tests/ui/rust-2024/safe-outside-extern.rs
@@ -0,0 +1,9 @@
+//@ revisions: gated ungated
+
+// Very pared down version of the same named test on nightly, since we only want
+// to validate that `unsafe static` is not being accidentally accepted by the parser.
+
+unsafe static LOL: u8 = 0;
+//~^ ERROR: static items cannot be declared with `unsafe` safety qualifier outside of `extern` block
+
+fn main() {}
diff --git a/tests/ui/rust-2024/safe-outside-extern.ungated.stderr b/tests/ui/rust-2024/safe-outside-extern.ungated.stderr
new file mode 100644
index 0000000000000..a81f8382859d0
--- /dev/null
+++ b/tests/ui/rust-2024/safe-outside-extern.ungated.stderr
@@ -0,0 +1,8 @@
+error: static items cannot be declared with `unsafe` safety qualifier outside of `extern` block
+  --> $DIR/safe-outside-extern.rs:6:1
+   |
+LL | unsafe static LOL: u8 = 0;
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+