[gcc r16-6840] gccrs: add redudant semicolon lint

[Arthur Cohen]

https://gcc.gnu.org/g:0655ee82b9938861d49f86ef3d5cb0a65fdc1d3e

commit r16-6840-g0655ee82b9938861d49f86ef3d5cb0a65fdc1d3e
Author: Lucas Ly Ba <lucas.ly-ba@outlook.com>
Date:   Tue Jan 6 11:21:13 2026 +0000

    gccrs: add redudant semicolon lint
    
    gcc/rust/ChangeLog:
    
            * checks/lints/unused/rust-unused-checker.cc (UnusedChecker::visit):
            Emit warning in empty statement visitor.
            * checks/lints/unused/rust-unused-checker.h:
            Likewise.
    
    gcc/testsuite/ChangeLog:
    
            * rust/compile/redundant-semicolons_0.rs: New test.
    
    Signed-off-by: Lucas Ly Ba <lucas.ly-ba@outlook.com>

Diff:
---
 gcc/rust/checks/lints/unused/rust-unused-checker.cc  |  7 +++++++
 gcc/rust/checks/lints/unused/rust-unused-checker.h   |  1 +
 gcc/testsuite/rust/compile/redundant-semicolons_0.rs | 10 ++++++++++
 3 files changed, 18 insertions(+)

diff --git a/gcc/rust/checks/lints/unused/rust-unused-checker.cc b/gcc/rust/checks/lints/unused/rust-unused-checker.cc
index 45715dac43e7..235acd6a4065 100644
--- a/gcc/rust/checks/lints/unused/rust-unused-checker.cc
+++ b/gcc/rust/checks/lints/unused/rust-unused-checker.cc
@@ -117,5 +117,12 @@ UnusedChecker::visit (HIR::StructPatternFieldIdent &pattern)
 		     pattern.get_identifier ().as_string ().c_str ());
 }
 
+void
+UnusedChecker::visit (HIR::EmptyStmt &stmt)
+{
+  rust_warning_at (stmt.get_locus (), OPT_Wunused_variable,
+		   "unnecessary trailing semicolons");
+}
+
 } // 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 ac7d2169781e..061d0c6f0029 100644
--- a/gcc/rust/checks/lints/unused/rust-unused-checker.h
+++ b/gcc/rust/checks/lints/unused/rust-unused-checker.h
@@ -43,6 +43,7 @@ private:
   virtual void visit (HIR::IdentifierPattern &identifier) override;
   virtual void visit (HIR::AssignmentExpr &identifier) override;
   virtual void visit (HIR::StructPatternFieldIdent &identifier) override;
+  virtual void visit (HIR::EmptyStmt &stmt) override;
 };
 } // namespace Analysis
 } // namespace Rust
diff --git a/gcc/testsuite/rust/compile/redundant-semicolons_0.rs b/gcc/testsuite/rust/compile/redundant-semicolons_0.rs
new file mode 100644
index 000000000000..57d7c9ad3a06
--- /dev/null
+++ b/gcc/testsuite/rust/compile/redundant-semicolons_0.rs
@@ -0,0 +1,10 @@
+// { dg-additional-options "-frust-unused-check-2.0" }
+
+pub fn foo() -> i32 
+{
+    let a = 32;;
+// { dg-warning "unnecessary trailing semicolons" "" { target *-*-* } .-1 }
+    return a
+}
+
+