diff -r 40949afe3df8 sys/src/cmd/cc/cc.y
--- a/sys/src/cmd/cc/cc.y	Mon Jun 17 13:17:16 2019 +0930
+++ b/sys/src/cmd/cc/cc.y	Mon Jun 17 15:55:14 2019 -0700
@@ -499,14 +499,6 @@
 	{
 		$$ = new(OGOTO, dcllabel($2, 0), Z);
 	}
-|	LUSED '(' zelist ')' ';'
-	{
-		$$ = new(OUSED, $3, Z);
-	}
-|	LSET '(' zelist ')' ';'
-	{
-		$$ = new(OSET, $3, Z);
-	}
 
 zcexpr:
 	{
@@ -733,6 +725,14 @@
 		dodecl(NODECL, CXXX, $3, $4);
 		$$->type = lastdcl;
 	}
+|	LUSED '(' zelist ')'
+	{
+		$$ = new(OUSED, $3, Z);
+	}
+|	LSET '(' zelist ')'
+	{
+		$$ = new(OSET, $3, Z);
+	}
 |	pexpr '(' zelist ')'
 	{
 		$$ = new(OFUNC, $1, Z);
diff -r 40949afe3df8 sys/src/cmd/cc/com.c
--- a/sys/src/cmd/cc/com.c	Mon Jun 17 13:17:16 2019 +0930
+++ b/sys/src/cmd/cc/com.c	Mon Jun 17 15:55:14 2019 -0700
@@ -81,6 +81,15 @@
 		diag(n, "unknown op in type complex: %O", n->op);
 		goto bad;
 
+	case OUSED:
+	case OSET:
+		/*
+		 * If the node is inside an expression, USED
+		 * and SET are useless; shift the child up.
+		 */
+		*n = *n->left;
+		break;
+
 	case ODOTDOT:
 		/*
 		 * tcom has already been called on this subtree