[ubsan] Diagnose noreturn functions which return (compiler-rt)

[vsk]

Summary

This is a test and a wording update for the clang change: https://reviews.llvm.org/D40698

[vsk]

• Update to test diagnostics seen after a call to the noreturn function.

lib/ubsan/ubsan_handlers.cc

void __ubsan::__ubsan_handle_out_of_bounds_abort(OutOfBoundsData *Data,
   GET_REPORT_OPTIONS(true);
   handleOutOfBoundsImpl(Data, Index, Opts);
   Die();
 }
 
 static void handleBuiltinUnreachableImpl(UnreachableData *Data,
                                          ReportOptions Opts) {
   ScopedReport R(Opts, Data->Loc, ErrorType::UnreachableCall);
-  Diag(Data->Loc, DL_Error, "execution reached a __builtin_unreachable() call");
+  Diag(Data->Loc, DL_Error, "execution reached an unreachable program point");
 }
 
 void __ubsan::__ubsan_handle_builtin_unreachable(UnreachableData *Data) {
   GET_REPORT_OPTIONS(true);
   handleBuiltinUnreachableImpl(Data, Opts);
   Die();
 }
 

test/ubsan/TestCases/Misc/unreachable.cpp

-// RUN: %clangxx -fsanitize=unreachable %s -O3 -o %t && not %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx -fsanitize=unreachable %s -O3 -o %t
+// RUN: not %run %t builtin 2>&1 | FileCheck %s -check-prefix=BUILTIN
+// RUN: not %run %t noreturn 2>&1 | FileCheck %s -check-prefix=NORETURN
+
+#include <string.h>
+
+void __attribute__((noreturn)) return_unexpectedly() {
+  // NORETURN: unreachable.cpp:[[@LINE+1]]:1: runtime error: execution reached an unreachable program point
+}
 
 int main(int, char **argv) {
-  // CHECK: unreachable.cpp:5:3: runtime error: execution reached a __builtin_unreachable() call
+  if (strcmp(argv[1], "builtin") == 0)
+    // BUILTIN: unreachable.cpp:[[@LINE+1]]:5: runtime error: execution reached an unreachable program point
     __builtin_unreachable();
+  else if (strcmp(argv[1], "noreturn") == 0)
+    return_unexpectedly();
+  return 0;
 }