Thanks,
Arthur On 8/7/26 2:39 PM, [email protected] wrote:
From: Lucas Ly Ba <[email protected]> Warn on taking a reference to a mutable static, which is discouraged as it can easily lead to undefined behaviour. gcc/rust/ChangeLog: * checks/lints/unused/rust-unused-checker.cc (UnusedChecker::visit): New. * checks/lints/unused/rust-unused-checker.h (UnusedChecker::visit): New. * rust-lang.cc (grs_langhook_init_options_struct): Enable warn_unused. gcc/testsuite/ChangeLog: * rust/compile/static-mut-refs_0.rs: New test. Signed-off-by: Lucas Ly Ba <[email protected]> --- .../lints/unused/rust-unused-checker.cc | 20 +++++++++++++++++++ .../checks/lints/unused/rust-unused-checker.h | 1 + .../rust/compile/static-mut-refs_0.rs | 13 ++++++++++++ 3 files changed, 34 insertions(+) create mode 100644 gcc/testsuite/rust/compile/static-mut-refs_0.rs diff --git a/gcc/rust/checks/lints/unused/rust-unused-checker.cc b/gcc/rust/checks/lints/unused/rust-unused-checker.cc index 0d091e6473a..fffe61dd129 100644 --- a/gcc/rust/checks/lints/unused/rust-unused-checker.cc +++ b/gcc/rust/checks/lints/unused/rust-unused-checker.cc @@ -347,5 +347,25 @@ UnusedChecker::visit (HIR::LetStmt &stmt) walk (stmt); }+void+UnusedChecker::visit (HIR::BorrowExpr &expr) +{ + // The static_mut_refs lint: taking a reference to a mutable static is + // discouraged as it can easily lead to undefined behaviour. + NodeId ast_node_id = expr.get_expr ().get_mappings ().get_nodeid (); + if (auto def + = nr_context.lookup (ast_node_id, Resolver2_0::Namespace::Values)) + if (auto id = mappings.lookup_node_to_hir (*def)) + if (auto item = mappings.lookup_hir_item (*id)) + if (item.value ()->get_item_kind () == HIR::Item::ItemKind::Static) + { + auto &static_item = static_cast<HIR::StaticItem &> (*item.value ()); + if (static_item.is_mut ()) + rust_warning_at (expr.get_locus (), OPT_Wunused, + "creating a reference to a mutable static"); + } + walk (expr); +} + } // namespace Analysis } // namespace Rust diff --git a/gcc/rust/checks/lints/unused/rust-unused-checker.h b/gcc/rust/checks/lints/unused/rust-unused-checker.h index 46e012e7907..161f59b8a66 100644 --- a/gcc/rust/checks/lints/unused/rust-unused-checker.h +++ b/gcc/rust/checks/lints/unused/rust-unused-checker.h @@ -52,6 +52,7 @@ private: virtual void visit (HIR::MatchExpr &expr) override; virtual void visit (HIR::ExternBlock &block) override; virtual void visit (HIR::LetStmt &stmt) override; + virtual void visit (HIR::BorrowExpr &expr) override; virtual void visit_loop_label (HIR::LoopLabel &label) override; }; } // namespace Analysis diff --git a/gcc/testsuite/rust/compile/static-mut-refs_0.rs b/gcc/testsuite/rust/compile/static-mut-refs_0.rs new file mode 100644 index 00000000000..5dcc5978a74 --- /dev/null +++ b/gcc/testsuite/rust/compile/static-mut-refs_0.rs @@ -0,0 +1,13 @@ +// { dg-additional-options "-frust-unused-check-2.0" } +#![feature(no_core, lang_items)] +#![no_core] + +#[lang = "sized"] +pub trait Sized {} + +static mut S: i32 = 0; + +pub unsafe fn f() { + let _y = &S; +// { dg-warning "reference to a mutable static" "" { target *-*-* } .-1 } +}
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