Conditionally compile items declared as statements. Issue #489

Author: brson

src/comp/front/config.rs

@@ -11,7 +11,8 @@ export strip_unconfigured_items;
 fn strip_unconfigured_items(@ast::crate crate) -> @ast::crate {
     auto cfg = crate.node.config;
 
-    auto precursor = rec(fold_mod = bind fold_mod(cfg, _, _)
+    auto precursor = rec(fold_mod = bind fold_mod(cfg, _, _),
+                         fold_block = bind fold_block(cfg, _, _)
                          with *fold::default_ast_fold());
 
     auto fold = fold::make_fold(precursor);
@@ -38,6 +39,34 @@ fn fold_mod(&ast::crate_cfg cfg, &ast::_mod m,
             items=vec::map(fld.fold_item, filtered_items));
 }
 
+fn filter_stmt(&ast::crate_cfg cfg,
+               &@ast::stmt stmt) -> option::t[@ast::stmt] {
+    alt (stmt.node) {
+        case (ast::stmt_decl(?decl, _)) {
+            alt (decl.node) {
+                case (ast::decl_item(?item)) {
+                    if (in_cfg(cfg, item)) {
+                        option::some(stmt)
+                    } else {
+                        option::none
+                    }
+                }
+                case (_) { option::some(stmt) }
+            }
+        }
+        case (_) { option::some(stmt) }
+    }
+}
+
+fn fold_block(&ast::crate_cfg cfg, &ast::block_ b,
+              fold::ast_fold fld) -> ast::block_  {
+    auto filter = bind filter_stmt(cfg, _);
+    auto filtered_stmts = vec::filter_map(filter, b.stmts);
+    ret rec(stmts=vec::map(fld.fold_stmt, filtered_stmts),
+            expr=option::map(fld.fold_expr, b.expr),
+            id=b.id);
+}
+
 // Determine if an item should be translated in the current crate
 // configuration based on the item's attributes
 fn in_cfg(&ast::crate_cfg cfg, &@ast::item item) -> bool {

src/test/run-pass/conditional-compile.rs

@@ -70,5 +70,18 @@ fn main() {
   assert b;
   let t x = true;
   let tg y = bar;
+
+  test_in_fn_ctxt();
 }
 
+fn test_in_fn_ctxt() {
+  #[cfg(bogus)]
+  fn f() { fail }
+  fn f() {}
+  f();
+
+  #[cfg(bogus)]
+  const int i = 0;
+  const int i = 1;
+  assert i == 1;
+}