Use a unique exit status when the runtime fails normally

Check for it in run-fail tests

src/rt/rust_internal.h

@@ -99,6 +99,9 @@ static size_t const TIME_SLICE_IN_MS = 10;
 
 static size_t const BUF_BYTES = 2048;
 
+// The error status to use when the process fails
+#define PROC_FAIL_CODE 101;
+
 // Every reference counted object should use this macro and initialize
 // ref_count.
 

src/rt/rust_kernel.cpp

@@ -140,7 +140,7 @@ rust_kernel::fail() {
     // Runtime to terminate it in an unusual way" when trying to shutdown
     // cleanly.
 #if defined(__WIN32__)
-    exit(1);
+    exit(rval);
 #endif
     for(size_t i = 0; i < num_threads; ++i) {
         rust_scheduler *thread = threads[i];

src/rt/rust_scheduler.cpp

@@ -71,7 +71,7 @@ rust_scheduler::fail() {
     log(NULL, log_err, "domain %s @0x%" PRIxPTR " root task failed",
         name, this);
     I(this, kernel->rval == 0);
-    kernel->rval = 1;
+    kernel->rval = PROC_FAIL_CODE;
     kernel->fail();
 }
 

src/test/compiletest/runtest.rs

@@ -51,15 +51,21 @@ fn run_rfail_test(cx: &cx, props: &test_props, testfile: &str) {
 
     procres = exec_compiled_test(cx, props, testfile);
 
-    if procres.status == 0 {
-        fatal_procres("run-fail test didn't produce an error!", procres);
-    }
-
+    // The value our Makefile configures valgrind to return on failure
     const valgrind_err: int = 100;
     if procres.status == valgrind_err {
         fatal_procres("run-fail test isn't valgrind-clean!", procres);
     }
 
+    // The value the rust runtime returns on failure
+    const rust_err: int = 101;
+    if procres.status != rust_err {
+        fatal_procres(
+            #fmt("run-fail test produced the wrong error code: %d",
+                 procres.status),
+            procres);
+    }
+
     check_error_patterns(props, testfile, procres);
 }