Disallow hidden references to mutable static

Author: obeis

compiler/rustc_hir_analysis/src/check/errs.rs

@@ -10,11 +10,36 @@ use crate::errors;
 pub fn maybe_expr_static_mut(tcx: TyCtxt<'_>, expr: hir::Expr<'_>) {
     let span = expr.span;
     let hir_id = expr.hir_id;
-    if let hir::ExprKind::AddrOf(borrow_kind, m, expr) = expr.kind
-        && matches!(borrow_kind, hir::BorrowKind::Ref)
-        && let Some(var) = path_if_static_mut(tcx, expr)
-    {
-        handle_static_mut_ref(tcx, span, var, span.edition().at_least_rust_2024(), m, hir_id);
+    match expr.kind {
+        hir::ExprKind::AddrOf(borrow_kind, m, expr) => {
+            if matches!(borrow_kind, hir::BorrowKind::Ref)
+                && let Some(var) = path_if_static_mut(tcx, expr)
+            {
+                handle_static_mut_ref(
+                    tcx,
+                    span,
+                    var,
+                    span.edition().at_least_rust_2024(),
+                    m,
+                    hir_id,
+                    true,
+                );
+            }
+        }
+        hir::ExprKind::MethodCall(_, expr, _, _) | hir::ExprKind::Index(expr, _, _) => {
+            if let Some(var) = path_if_static_mut(tcx, expr) {
+                handle_static_mut_ref(
+                    tcx,
+                    span,
+                    var,
+                    span.edition().at_least_rust_2024(),
+                    Mutability::Not,
+                    hir_id,
+                    false,
+                );
+            }
+        }
+        _ => {}
     }
 }
 
@@ -33,6 +58,7 @@ pub fn maybe_stmt_static_mut(tcx: TyCtxt<'_>, stmt: hir::Stmt<'_>) {
             loc.span.edition().at_least_rust_2024(),
             rmutbl,
             stmt.hir_id,
+            true,
         );
     }
 }
@@ -55,25 +81,42 @@ fn handle_static_mut_ref(
     e2024: bool,
     mutable: Mutability,
     hir_id: hir::HirId,
+    suggest: bool,
 ) {
+    let shared = if mutable == Mutability::Mut { "mutable" } else { "shared" };
     if e2024 {
-        let (sugg, shared) = if mutable == Mutability::Mut {
-            (errors::StaticMutRefSugg::Mut { span, var }, "mutable")
-        } else {
-            (errors::StaticMutRefSugg::Shared { span, var }, "shared")
-        };
-        tcx.sess.psess.dcx.emit_err(errors::StaticMutRef { span, sugg, shared });
-    } else {
-        let (sugg, shared) = if mutable == Mutability::Mut {
-            (errors::RefOfMutStaticSugg::Mut { span, var }, "mutable")
+        if suggest {
+            let sugg = if mutable == Mutability::Mut {
+                errors::StaticMutRefSugg::Mut { span, var }
+            } else {
+                errors::StaticMutRefSugg::Shared { span, var }
+            };
+            tcx.sess.psess.dcx.emit_err(errors::StaticMutRef { span, sugg: Some(sugg), shared });
+            return;
+        }
+        tcx.sess.psess.dcx.emit_err(errors::StaticMutRef { span, sugg: None, shared });
+        return;
+    }
+
+    if suggest {
+        let sugg = if mutable == Mutability::Mut {
+            errors::RefOfMutStaticSugg::Mut { span, var }
         } else {
-            (errors::RefOfMutStaticSugg::Shared { span, var }, "shared")
+            errors::RefOfMutStaticSugg::Shared { span, var }
         };
         tcx.emit_node_span_lint(
             STATIC_MUT_REFS,
             hir_id,
             span,
-            errors::RefOfMutStatic { span, sugg, shared },
+            errors::RefOfMutStatic { span, sugg: Some(sugg), shared },
         );
+        return;
     }
+
+    tcx.emit_node_span_lint(
+        STATIC_MUT_REFS,
+        hir_id,
+        span,
+        errors::RefOfMutStatic { span, sugg: None, shared },
+    );
 }

compiler/rustc_hir_analysis/src/errors.rs

@@ -1500,7 +1500,7 @@ pub struct StaticMutRef<'a> {
     #[label]
     pub span: Span,
     #[subdiagnostic]
-    pub sugg: StaticMutRefSugg,
+    pub sugg: Option<StaticMutRefSugg>,
     pub shared: &'a str,
 }
 
@@ -1539,7 +1539,7 @@ pub struct RefOfMutStatic<'a> {
     #[label]
     pub span: Span,
     #[subdiagnostic]
-    pub sugg: RefOfMutStaticSugg,
+    pub sugg: Option<RefOfMutStaticSugg>,
     pub shared: &'a str,
 }