middle: Add a pass to reject bad const expressions earlier. Currently just rejects unimplemented const expressions, but will be needed later.

Author: jwise

src/comp/driver/rustc.rs

@@ -151,6 +151,8 @@ fn compile_input(sess: session::session, cfg: ast::crate_cfg, input: str,
         time(time_passes, "alias checking",
              bind middle::alias::check_crate(ty_cx, crate));
     time(time_passes, "kind checking", bind kind::check_crate(ty_cx, crate));
+    time(time_passes, "const checking",
+         bind middle::check_const::check_crate(ty_cx, crate));
     if sess.get_opts().no_trans { ret; }
     let llmod =
         time(time_passes, "translation",

src/comp/middle/check_const.rs

@@ -0,0 +1,42 @@
+import syntax::ast::*;
+import syntax::ast_util::{variant_def_ids, dummy_sp};
+import syntax::visit;
+
+fn check_crate(tcx: ty::ctxt, crate: @crate) {
+    let v =
+        @{visit_item: bind check_item(tcx, _, _, _)
+             with *visit::default_visitor::<()>()};
+    visit::visit_crate(*crate, (), visit::mk_vt(v));
+    tcx.sess.abort_if_errors();
+}
+
+fn check_item(tcx: ty::ctxt, it: @item, &&s: (), v: visit::vt<()>) {
+    visit::visit_item(it, s, v);
+    alt it.node {
+      item_const(_ /* ty */, ex) {
+         let v =
+             @{visit_expr: bind check_const_expr(tcx, _, _, _)
+                  with *visit::default_visitor::<()>()};
+         check_const_expr(tcx, ex, (), visit::mk_vt(v));
+       }
+       _ { }
+    }
+}
+
+fn check_const_expr(tcx: ty::ctxt, ex: @expr, &&s: (), v: visit::vt<()>) {
+    visit::visit_expr(ex, s, v);
+    alt ex.node {
+      expr_lit(_) { }
+      _ { tcx.sess.span_err(ex.span,
+          "constant contains unimplemented expression type"); }
+    }
+}
+
+// Local Variables:
+// mode: rust
+// fill-column: 78;
+// indent-tabs-mode: nil
+// c-basic-offset: 4
+// buffer-file-coding-system: utf-8-unix
+// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
+// End:

src/comp/rustc.rc

@@ -27,6 +27,7 @@ mod middle {
     mod typeck;
     mod fn_usage;
     mod check_alt;
+    mod check_const;
     mod mut;
     mod alias;
     mod kind;