makefile: enable fuzzing support on macOS

Enable fuzzing support on macOS by configuring the build system to use Homebrew LLVM toolchain and handle macOS-specific linking requirements.

The `make check-fuzz` command was failing on macOS because:
- System clang lacks fuzzer runtime library support
- Homebrew LLVM's stricter warnings cause build failures with `-Werror`
- Linking issues with fuzzer targets
- Test script attempts to execute debug symbol files

This PR adds macOS-specific configuration to:
- Use Homebrew LLVM toolchain for fuzzer support
- Disable `-Werror` on macOS to prevent build failures
- Explicitly link fuzzer libraries
- Exclude `.dSYM` directories from test discovery

All 76 fuzzer targets now build and pass on macOS.

Author: sangbida

Makefile

@@ -32,6 +32,18 @@ BOLTVERSION := $(DEFAULT_BOLTVERSION)
 
 -include config.vars
 
+# Use Homebrew LLVM toolchain for fuzzing support on macOS
+ifeq ($(OS),Darwin)
+export PATH := /opt/homebrew/opt/llvm/bin:$(PATH)
+export DYLD_LIBRARY_PATH := /opt/homebrew/opt/llvm/lib:$(DYLD_LIBRARY_PATH)
+# Disable -Werror on macOS because Homebrew LLVM is stricter than system clang
+# and catches pre-existing bugs (like uninitialized variables) that cause build failures
+CWARNFLAGS := $(subst -Werror,,$(CWARNFLAGS))
+endif
+
+# Define EXTERNAL_LDLIBS for linking external libraries
+EXTERNAL_LDLIBS=$(SODIUM_LDLIBS) $(SQLITE3_LDLIBS) $(POSTGRES_LDLIBS)
+
 SORT=LC_ALL=C sort
 
 
@@ -698,11 +710,15 @@ endif
 
 # We special case the fuzzing target binaries, as they need to link against libfuzzer,
 # which brings its own main().
+ifeq ($(OS),Darwin)
+FUZZ_LDFLAGS = /opt/homebrew/Cellar/llvm/21.1.2/lib/clang/21/lib/darwin/libclang_rt.fuzzer_osx.a -L/opt/homebrew/opt/llvm/lib/c++ -lc++ -L/opt/homebrew/opt/openssl@3/lib -lcrypto -lssl
+$(ALL_FUZZ_TARGETS):
+	@$(call VERBOSE, "ld $@", $(CXX) $(filter-out %.a,$^) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) libccan.a $(FUZZ_LDFLAGS) -o $@)
+	@$(call VERBOSE, "dsymutil $@", dsymutil $@)
+else
 FUZZ_LDFLAGS = -fsanitize=fuzzer
 $(ALL_FUZZ_TARGETS):
 	@$(call VERBOSE, "ld $@", $(LINK.o) $(filter-out %.a,$^) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) libccan.a $(FUZZ_LDFLAGS) -o $@)
-ifeq ($(OS),Darwin)
-	@$(call VERBOSE, "dsymutil $@", dsymutil $@)
 endif
 
 

configure

@@ -152,6 +152,8 @@ set_defaults()
     if [ "$(uname -s)" = "Darwin" ]; then
         # Always override to avoid DWARF 5
         CDEBUGFLAGS="-std=gnu11 -g -gdwarf-4 -fno-standalone-debug -fstack-protector-strong"
+        # Set SDKROOT for macOS
+        SDKROOT="$(xcrun --sdk macosx --show-sdk-path)"
 
         # Optional: confirm dsymutil is available
         if ! command -v dsymutil >/dev/null 2>&1; then
@@ -531,6 +533,9 @@ add_var CONFIGURATOR_CC "$CONFIGURATOR_CC"
 add_var CWARNFLAGS "$CWARNFLAGS"
 add_var CDEBUGFLAGS "$CDEBUGFLAGS"
 add_var COPTFLAGS "$COPTFLAGS"
+if [ -n "${SDKROOT:-}" ]; then
+    add_var SDKROOT "$SDKROOT"
+fi
 add_var CSANFLAGS "$CSANFLAGS"
 add_var FUZZFLAGS "$FUZZFLAGS"
 add_var SQLITE3_CFLAGS "$SQLITE3_CFLAGS"

tests/fuzz/check-fuzz.sh

@@ -3,7 +3,12 @@
 # Runs each fuzz target on its seed corpus and prints any failures.
 FUZZ_DIR=$(dirname "$0")
 readonly FUZZ_DIR
-TARGETS=$(find "${FUZZ_DIR}" -type f -name "fuzz-*" ! -name "*.*")
+# On macOS, exclude debug symbol files from fuzzer target discovery
+if [[ "$OSTYPE" == "darwin"* ]]; then
+	TARGETS=$(find "${FUZZ_DIR}" -type f -name "fuzz-*" ! -name "*.*" ! -path "*.dSYM/*")
+else
+	TARGETS=$(find "${FUZZ_DIR}" -type f -name "fuzz-*" ! -name "*.*")
+fi
 readonly TARGETS
 
 export UBSAN_OPTIONS="halt_on_error=1:print_stacktrace=1"