From fae7a1c18803675e70b9bf66575e1e0a6e01f6f6 Mon Sep 17 00:00:00 2001
From: MarcoFalke <falke.marco@gmail.com>
Date: Sat, 3 Oct 2020 10:54:28 +0200
Subject: fuzz: Configure check for main function

---
 configure.ac           | 14 ++++++++++++++
 src/test/fuzz/fuzz.cpp |  9 ---------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/configure.ac b/configure.ac
index fbf56443f1..674ed1ee73 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1165,6 +1165,20 @@ if test "x$enable_fuzz" = "xyes"; then
   use_bench=no
   use_upnp=no
   use_zmq=no
+
+  AC_MSG_CHECKING([whether main function is needed])
+  AX_CHECK_LINK_FLAG(
+    [[-fsanitize=$use_sanitizers]],
+    [AC_MSG_RESULT([no])],
+    [AC_MSG_RESULT([yes])
+     CPPFLAGS="$CPPFLAGS -DPROVIDE_MAIN_FUNCTION"],
+    [],
+    [AC_LANG_PROGRAM([[
+      #include <cstdint>
+      #include <cstddef>
+      extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) { return 0; }
+      /* unterminated comment to remove the main function ...
+    ]],[[]])])
 else
   BITCOIN_QT_INIT
 
diff --git a/src/test/fuzz/fuzz.cpp b/src/test/fuzz/fuzz.cpp
index 1e1807d734..753cfffdcb 100644
--- a/src/test/fuzz/fuzz.cpp
+++ b/src/test/fuzz/fuzz.cpp
@@ -12,15 +12,6 @@
 
 const std::function<void(const std::string&)> G_TEST_LOG_FUN{};
 
-// Decide if main(...) should be provided:
-// * AFL needs main(...) regardless of platform.
-// * macOS handles __attribute__((weak)) main(...) poorly when linking
-//   against libFuzzer. See https://github.com/bitcoin/bitcoin/pull/18008
-//   for details.
-#if defined(__AFL_COMPILER) || !defined(MAC_OSX)
-#define PROVIDE_MAIN_FUNCTION
-#endif
-
 #if defined(PROVIDE_MAIN_FUNCTION)
 static bool read_stdin(std::vector<uint8_t>& data)
 {
-- 
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