From 3878906121e994aaf878b763ec8b7e141d96125b Mon Sep 17 00:00:00 2001
From: kennytm <kennytm@gmail.com>
Date: Sun, 11 Feb 2018 05:05:11 +0800
Subject: [PATCH] Improve debuggability of #48116.

1. When the invalid condition is hit, write out the relevant variables too
2. In compile-fail/parse-fail tests, check for ICE first, so the invalid
   error patterns won't mask our ICE output.
---
 src/librustc_resolve/resolve_imports.rs | 15 +++++++++++++--
 src/tools/compiletest/src/runtest.rs    |  2 +-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/librustc_resolve/resolve_imports.rs b/src/librustc_resolve/resolve_imports.rs
index 8cb25f449b667..a8070c553bdbc 100644
--- a/src/librustc_resolve/resolve_imports.rs
+++ b/src/librustc_resolve/resolve_imports.rs
@@ -1026,6 +1026,8 @@ fn import_path_to_string(names: &[SpannedIdent],
         if names.is_empty() {
             import_directive_subclass_to_string(subclass)
         } else {
+            // FIXME: Remove this entire logic after #48116 is fixed.
+            //
             // Note that this code looks a little wonky, it's currently here to
             // hopefully help debug #48116, but otherwise isn't intended to
             // cause any problems.
@@ -1034,8 +1036,17 @@ fn import_path_to_string(names: &[SpannedIdent],
                 names_to_string(names),
                 import_directive_subclass_to_string(subclass),
             );
-            assert!(!names.is_empty());
-            assert!(!x.starts_with("::"));
+            if names.is_empty() || x.starts_with("::") {
+                span_bug!(
+                    span,
+                    "invalid name `{}` at {:?}; global = {}, names = {:?}, subclass = {:?}",
+                    x,
+                    span,
+                    global,
+                    names,
+                    subclass
+                );
+            }
             return x
         }
     }
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index a87809dd7bcfd..bef085e17ea16 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -250,6 +250,7 @@ impl<'test> TestCx<'test> {
     fn run_cfail_test(&self) {
         let proc_res = self.compile_test();
         self.check_if_test_should_compile(&proc_res);
+        self.check_no_compiler_crash(&proc_res);
 
         let output_to_check = self.get_output(&proc_res);
         let expected_errors = errors::load_errors(&self.testpaths.file, self.revision);
@@ -262,7 +263,6 @@ impl<'test> TestCx<'test> {
             self.check_error_patterns(&output_to_check, &proc_res);
         }
 
-        self.check_no_compiler_crash(&proc_res);
         self.check_forbid_output(&output_to_check, &proc_res);
     }