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
- 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
- Explicitly link fuzzer libraries
- Exclude `.dSYM` directories from test discovery

All 76 fuzzer targets now build and pass on macOS.

Makefile

@@ -32,6 +32,15 @@ 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:$(DYLD_LIBRARY_PATH)
+endif
+
+# Define EXTERNAL_LDLIBS for linking external libraries
+EXTERNAL_LDLIBS=$(SODIUM_LDLIBS) $(SQLITE3_LDLIBS) $(POSTGRES_LDLIBS)
+
 SORT=LC_ALL=C sort
 
 
@@ -254,8 +263,8 @@ man8dir = $(mandir)/man8
 ifeq ("$(OS)-$(ARCH)", "Darwin-arm64")
 CPATH := /opt/homebrew/include
 LIBRARY_PATH := /opt/homebrew/lib
-LDFLAGS := -L/opt/homebrew/opt/sqlite/lib
-CPPFLAGS := -I/opt/homebrew/opt/sqlite/include
+LDFLAGS := -L/opt/homebrew/opt/sqlite/lib -L/opt/homebrew/opt/openssl@3/lib
+CPPFLAGS := -I/opt/homebrew/opt/sqlite/include -I/opt/homebrew/opt/openssl@3/include
 PKG_CONFIG_PATH=/opt/homebrew/opt/sqlite/lib/pkgconfig
 else
 CPATH := /usr/local/include
@@ -698,7 +707,17 @@ endif
 
 # We special case the fuzzing target binaries, as they need to link against libfuzzer,
 # which brings its own main().
+# FUZZER_LIB and LLVM_LDFLAGS are set by configure script on macOS
+ifeq ($(OS),Darwin)
+ifneq ($(FUZZER_LIB),)
+FUZZ_LDFLAGS = $(FUZZER_LIB) $(LLVM_LDFLAGS)
+else
 FUZZ_LDFLAGS = -fsanitize=fuzzer
+endif
+else
+FUZZ_LDFLAGS = -fsanitize=fuzzer
+endif
+
 $(ALL_FUZZ_TARGETS):
 	@$(call VERBOSE, "ld $@", $(LINK.o) $(filter-out %.a,$^) $(LOADLIBES) $(EXTERNAL_LDLIBS) $(LDLIBS) libccan.a $(FUZZ_LDFLAGS) -o $@)
 ifeq ($(OS),Darwin)

configure

@@ -170,6 +170,8 @@ 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
@@ -538,6 +540,45 @@ if ! check_command 'jq' jq; then
     exit 1
 fi
 
+# Detect LLVM paths for fuzzing on macOS
+LLVM_LIBDIR=""
+FUZZER_LIB=""
+LLVM_LDFLAGS=""
+if [ "$OS" = "Darwin" ] && [ "$FUZZING" = "1" ]; then
+    echo -n "Detecting LLVM paths for fuzzing... "
+
+    # Try to find LLVM using Homebrew
+    if command -v brew >/dev/null 2>&1; then
+        LLVM_PREFIX=$(brew --prefix llvm 2>/dev/null || echo "")
+        if [ -n "$LLVM_PREFIX" ]; then
+            LLVM_LIBDIR="$LLVM_PREFIX/lib"
+
+            # Find the fuzzer library
+            # Look for libclang_rt.fuzzer_osx.a in the clang lib directories
+            CLANG_VERSION=$(ls -1 "$LLVM_LIBDIR/clang" 2>/dev/null | sort -V | tail -n1)
+            if [ -n "$CLANG_VERSION" ]; then
+                FUZZER_LIB="$LLVM_LIBDIR/clang/$CLANG_VERSION/lib/darwin/libclang_rt.fuzzer_osx.a"
+                if [ ! -f "$FUZZER_LIB" ]; then
+                    echo "Warning: Could not find fuzzer library at $FUZZER_LIB" >&2
+                    FUZZER_LIB=""
+                fi
+            fi
+
+            # Set LLVM C++ library path
+            if [ -d "$LLVM_PREFIX/lib/c++" ]; then
+                LLVM_LDFLAGS="-L$LLVM_PREFIX/lib/c++ -lc++"
+            fi
+
+            echo "found at $LLVM_PREFIX"
+        else
+            echo "not found"
+            echo "Warning: LLVM not found via Homebrew. Fuzzing may not work." >&2
+        fi
+    else
+        echo "not found (Homebrew not available)"
+    fi
+fi
+
 # Now we can finally set our warning flags
 if [ -z ${CWARNFLAGS+x} ]; then
     CWARNFLAGS=$(default_cwarnflags "$COPTFLAGS" \
@@ -551,8 +592,13 @@ add_var CONFIGURATOR_CC "$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 "$FUZZFLAGS"
+add_var FUZZER_LIB "$FUZZER_LIB"
+add_var LLVM_LDFLAGS "$LLVM_LDFLAGS"
 add_var SQLITE3_CFLAGS "$SQLITE3_CFLAGS"
 add_var SQLITE3_LDLIBS "$SQLITE3_LDLIBS"
 add_var POSTGRES_INCLUDE "$POSTGRES_INCLUDE"

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"