resolve-unused: Check for underscore before warning about unused

identifiers

5 files changed, 11 insertions, 4 deletions

diff --git a/gcc/rust/resolve/rust-ast-resolve-unused.h b/gcc/rust/resolve/rust-ast-resolve-unused.h
index 748f972..bd71110 100644
--- a/gcc/rust/resolve/rust-ast-resolve-unused.h
+++ b/gcc/rust/resolve/rust-ast-resolve-unused.h
@@ -30,7 +30,13 @@ public:
   static void ScanRib (Rib *r)
   {
     r->iterate_decls ([&] (NodeId decl_node_id, Location locus) -> bool {
-      if (!r->have_references_for_node (decl_node_id))
+      CanonicalPath ident = CanonicalPath::create_empty ();
+
+      bool ok = r->lookup_canonical_path (decl_node_id, &ident);
+      rust_assert (ok);
+
+      if (!r->have_references_for_node (decl_node_id)
+	  && ident.get ().at (0) != '_')
 	{
 	  rust_warning_at (locus, 0, "unused name");
 	}
diff --git a/gcc/testsuite/rust.test/compile/loop5.rs b/gcc/testsuite/rust.test/compile/loop5.rs
index 06f5f9e..4004cd3 100644
--- a/gcc/testsuite/rust.test/compile/loop5.rs
+++ b/gcc/testsuite/rust.test/compile/loop5.rs
@@ -4,7 +4,6 @@ fn main() {
 
     // first number in Fibonacci sequence over 10:
     let _fib = loop {
-        // { dg-bogus "unused name" "#361" { xfail *-*-* } .-1 }
         if b > 10 {
             break b;
         }
diff --git a/gcc/testsuite/rust.test/compile/loop7.rs b/gcc/testsuite/rust.test/compile/loop7.rs
index 647df13..0cd8445 100644
--- a/gcc/testsuite/rust.test/compile/loop7.rs
+++ b/gcc/testsuite/rust.test/compile/loop7.rs
@@ -3,7 +3,6 @@ fn main() {
     let mut b = 1;
 
     let _fib = loop {
-        // { dg-bogus "unused name" "#361" { xfail *-*-* } .-1 }
         if (a % 2 == 0) {
             continue;
         }
diff --git a/gcc/testsuite/rust.test/compile/struct_base_init_1.rs b/gcc/testsuite/rust.test/compile/struct_base_init_1.rs
index 781265a..3c0b24a 100644
--- a/gcc/testsuite/rust.test/compile/struct_base_init_1.rs
+++ b/gcc/testsuite/rust.test/compile/struct_base_init_1.rs
@@ -9,5 +9,4 @@ fn foo() -> Foo {
 
 fn main() {
     let _f = Foo { a: 10, ..foo() };
-    // { dg-bogus "unused name" "#361" { xfail *-*-* } .-1 }
 }
diff --git a/gcc/testsuite/rust.test/compile/underscore_id.rs b/gcc/testsuite/rust.test/compile/underscore_id.rs
new file mode 100644
index 0000000..2c106c5
--- /dev/null
+++ b/gcc/testsuite/rust.test/compile/underscore_id.rs
@@ -0,0 +1,4 @@
+fn main() {
+    let _unused_but_fine = 12;
+    let unused = 12; // { dg-warning "unused name" }
+}