Add syntax support for attributes on expressions and all syntax

nodes in statement position.

Extended #[cfg] folder to allow removal of statements, and
of expressions in optional positions like expression lists and trailing
block expressions.

Extended lint checker to recognize lint levels on expressions and
locals.

src/libsyntax/test.rs

@@ -88,7 +88,7 @@ pub fn modify_for_testing(sess: &ParseSess,
     if should_test {
         generate_test_harness(sess, reexport_test_harness_main, krate, cfg, span_diagnostic)
     } else {
-        strip_test_functions(krate)
+        strip_test_functions(span_diagnostic, krate)
     }
 }
 
@@ -314,10 +314,11 @@ fn generate_test_harness(sess: &ParseSess,
     return res;
 }
 
-fn strip_test_functions(krate: ast::Crate) -> ast::Crate {
+fn strip_test_functions(diagnostic: &diagnostic::SpanHandler, krate: ast::Crate)
+                        -> ast::Crate {
     // When not compiling with --test we should not compile the
     // #[test] functions
-    config::strip_items(krate, |attrs| {
+    config::strip_items(diagnostic, krate, |attrs| {
         !attr::contains_name(&attrs[..], "test") &&
         !attr::contains_name(&attrs[..], "bench")
     })
@@ -619,8 +620,10 @@ fn mk_test_descs(cx: &TestCtxt) -> P<ast::Expr> {
                     mk_test_desc_and_fn_rec(cx, test)
                 }).collect()),
                 span: DUMMY_SP,
+                attrs: None,
             })),
         span: DUMMY_SP,
+        attrs: None,
     })
 }