diff --git a/src/librustc/session/mod.rs b/src/librustc/session/mod.rs
index 500af5fc772..14bc19dffd5 100644
--- a/src/librustc/session/mod.rs
+++ b/src/librustc/session/mod.rs
@@ -57,6 +57,8 @@ pub struct Session {
     pub crate_metadata: RefCell<Vec<String>>,
     pub features: RefCell<feature_gate::Features>,
 
+    pub delayed_span_bug: RefCell<Option<(codemap::Span, String)>>,
+
     /// The maximum recursion limit for potentially infinitely recursive
     /// operations such as auto-dereference and monomorphization.
     pub recursion_limit: Cell<usize>,
@@ -114,7 +116,15 @@ impl Session {
         self.diagnostic().handler().has_errors()
     }
     pub fn abort_if_errors(&self) {
-        self.diagnostic().handler().abort_if_errors()
+        self.diagnostic().handler().abort_if_errors();
+
+        let delayed_bug = self.delayed_span_bug.borrow();
+        match *delayed_bug {
+            Some((span, ref errmsg)) => {
+                self.diagnostic().span_bug(span, errmsg);
+            },
+            _ => {}
+        }
     }
     pub fn span_warn(&self, sp: Span, msg: &str) {
         if self.can_print_warnings {
@@ -171,6 +181,11 @@ impl Session {
             None => self.bug(msg),
         }
     }
+    /// Delay a span_bug() call until abort_if_errors()
+    pub fn delay_span_bug(&self, sp: Span, msg: &str) {
+        let mut delayed = self.delayed_span_bug.borrow_mut();
+        *delayed = Some((sp, msg.to_string()));
+    }
     pub fn span_bug(&self, sp: Span, msg: &str) -> ! {
         self.diagnostic().span_bug(sp, msg)
     }
@@ -402,6 +417,7 @@ pub fn build_session_(sopts: config::Options,
         plugin_llvm_passes: RefCell::new(Vec::new()),
         crate_types: RefCell::new(Vec::new()),
         crate_metadata: RefCell::new(Vec::new()),
+        delayed_span_bug: RefCell::new(None),
         features: RefCell::new(feature_gate::Features::new()),
         recursion_limit: Cell::new(64),
         can_print_warnings: can_print_warnings
diff --git a/src/librustc_typeck/check/regionck.rs b/src/librustc_typeck/check/regionck.rs
index 9554e6ad8aa..55ad52dab95 100644
--- a/src/librustc_typeck/check/regionck.rs
+++ b/src/librustc_typeck/check/regionck.rs
@@ -544,7 +544,7 @@ fn visit_expr(rcx: &mut Rcx, expr: &ast::Expr) {
                 if tcx.sess.has_errors() {
                     // cannot run dropck; okay b/c in error state anyway.
                 } else {
-                    tcx.sess.span_bug(expr.span, "cat_expr_unadjusted Errd");
+                    tcx.sess.delay_span_bug(expr.span, "cat_expr Errd");
                 }
             }
         }
@@ -565,7 +565,7 @@ fn visit_expr(rcx: &mut Rcx, expr: &ast::Expr) {
             if tcx.sess.has_errors() {
                 // cannot run dropck; okay b/c in error state anyway.
             } else {
-                tcx.sess.span_bug(expr.span, "cat_expr Errd");
+                tcx.sess.delay_span_bug(expr.span, "cat_expr Errd");
             }
         }
     }
diff --git a/src/test/compile-fail/typeck-before-dropck-bug.rs b/src/test/compile-fail/typeck-before-dropck-bug.rs
new file mode 100644
index 00000000000..04ee993c040
--- /dev/null
+++ b/src/test/compile-fail/typeck-before-dropck-bug.rs
@@ -0,0 +1,31 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() { }
+
+// Before these errors would ICE as "cat_expr Errd" because the errors
+// were unknown when the bug was triggered.
+
+fn unconstrained_type() {
+    [];
+    //~^ ERROR cannot determine a type for this expression: unconstrained type
+}
+
+fn invalid_impl_within_scope() {
+    {
+        use std::ops::Deref;
+        struct Something;
+
+        impl Deref for Something {}
+        //~^ ERROR not all trait items implemented, missing: `Target`, `deref`
+
+        *Something
+    };
+}