[libFuzzer] when an invalid flag is given, warn, but don't crash

llvm-svn: 271404

2 files changed, 7 insertions, 2 deletions

diff --git a/llvm/lib/Fuzzer/FuzzerDriver.cpp b/llvm/lib/Fuzzer/FuzzerDriver.cpp
index 4cb5c05743b..3dc062b9311 100644
--- a/llvm/lib/Fuzzer/FuzzerDriver.cpp
+++ b/llvm/lib/Fuzzer/FuzzerDriver.cpp
@@ -163,8 +163,9 @@ static bool ParseOneFlag(const char *Param) {
       }
     }
   }
-  PrintHelp();
-  exit(1);
+  Printf("\n\nWARNING: unrecognized flag '%s'; "
+         "use -help=1 to list all flags\n\n", Param);
+  return true;
 }
 
 // We don't use any library to minimize dependencies.
diff --git a/llvm/lib/Fuzzer/test/fuzzer.test b/llvm/lib/Fuzzer/test/fuzzer.test
index b46d24eec33..e2f444f2694 100644
--- a/llvm/lib/Fuzzer/test/fuzzer.test
+++ b/llvm/lib/Fuzzer/test/fuzzer.test
@@ -99,6 +99,10 @@ RUN: LLVMFuzzer-SimpleTest %S/dict1.txt -runs=33 -print_final_stats=1 2>&1 | Fil
 FINAL_STATS1: stat::number_of_executed_units: 33
 FINAL_STATS1: stat::peak_rss_mb:
 
+RUN: LLVMFuzzer-SimpleTest -foo_bar=1 2>&1 | FileCheck %s --check-prefix=FOO_BAR
+FOO_BAR: WARNING: unrecognized flag '-foo_bar=1'; use -help=1 to list all flags
+FOO_BAR: BINGO
+
 RUN: LLVMFuzzer-SpamyTest -runs=1                  2>&1 | FileCheck %s --check-prefix=FD_MASK_0
 RUN: LLVMFuzzer-SpamyTest -runs=1 -close_fd_mask=0 2>&1 | FileCheck %s --check-prefix=FD_MASK_0
 RUN: LLVMFuzzer-SpamyTest -runs=1 -close_fd_mask=1 2>&1 | FileCheck %s --check-prefix=FD_MASK_1