[libFuzzer] add a better warning for command line flags with -- (two dashes)

llvm-svn: 266480

diff --git a/llvm/lib/Fuzzer/FuzzerDriver.cpp b/llvm/lib/Fuzzer/FuzzerDriver.cpp
index f47b337..256a0a7 100644 (file)
--- a/llvm/lib/Fuzzer/FuzzerDriver.cpp
+++ b/llvm/lib/Fuzzer/FuzzerDriver.cpp
@@ -133,6 +133,9 @@ static bool ParseOneFlag(const char *Param) {
       PrintedWarning = true;
       Printf("INFO: libFuzzer ignores flags that start with '--'\n");
     }
+    for (size_t F = 0; F < kNumFlags; F++)
+      if (FlagValue(Param + 1, FlagDescriptions[F].Name))
+        Printf("WARNING: did you mean '%s' (single dash)?\n", Param + 1);
     return true;
   }
   for (size_t F = 0; F < kNumFlags; F++) {

diff --git a/llvm/lib/Fuzzer/test/fuzzer.test b/llvm/lib/Fuzzer/test/fuzzer.test
index 9aca950..b42a49b 100644 (file)
--- a/llvm/lib/Fuzzer/test/fuzzer.test
+++ b/llvm/lib/Fuzzer/test/fuzzer.test
@@ -116,3 +116,5 @@ FD_MASK_3-NOT: STREAM_COUT
 FD_MASK_3-NOT: STREAM_CERR
 FD_MASK_3: INITED
 
+RUN: LLVMFuzzer-SimpleTest -runs=10 --max_len=100 2>&1 | FileCheck %s --check-prefix=DASH_DASH
+DASH_DASH: WARNING: did you mean '-max_len=100' (single dash)?