---

yaml
---
r: 4366
b: refs/heads/master
c: 13f8b3f
h: refs/heads/master
v: v3

Author: catamorphism

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7c34550931a457dd830173fc4a3c467a2ba2e784
+refs/heads/master: 13f8b3f2a67a4e3a7a26b0e238e1b6ce9e1f3573

trunk/src/comp/middle/trans.rs

@@ -3592,6 +3592,18 @@ fn trans_if(cx: &@block_ctxt, cond: &@ast::expr, thn: &ast::blk,
             els: &option::t[@ast::expr], id: ast::node_id,
             output: &out_method) -> result {
     let cond_res = trans_expr(cx, cond);
+
+    if (ty::type_is_bot(bcx_tcx(cx), ty::expr_ty(bcx_tcx(cx), cond))) {
+        // No need to generate code for comparison,
+        // since the cond diverges.
+        if (!cx.build.is_terminated()) {
+            ret rslt(cx, cx.build.Unreachable());
+        }
+        else {
+            ret rslt(cx, C_nil());
+        }
+    }
+
     let then_cx = new_scope_block_ctxt(cx, "then");
     let then_res = trans_block(then_cx, thn, output);
     let else_cx = new_scope_block_ctxt(cx, "else");

trunk/src/test/run-fail/if-cond-bot.rs

@@ -0,0 +1,3 @@
+// error-pattern:quux
+fn my_err(s: str) -> ! { log_err s; fail "quux"; }
+fn main() { if my_err("bye") { } }