Mark main and serverAssert as weak symbols to be overridden (valkey-i…

…o#1232)

At some point unit tests stopped building on MacOS because of duplicate
symbols. I had originally solved this problem by using a flag that
overrides symbols, but the much better solution is to mark the duplicate
symbols as weak and they can be overridden during linking. (Symbols by
default are strong, strong symbols override weak symbols)

I also added macos unit build to the CI, so that this doesn't silently
break in the future again.

---------

Signed-off-by: Madelyn Olson <[email protected]>
Co-authored-by: Viktor Söderqvist <[email protected]>

.github/workflows/ci.yml

@@ -83,7 +83,7 @@ jobs:
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
       - name: make
-        run: make -j3 SERVER_CFLAGS='-Werror'
+        run: make -j3 all-with-unit-tests SERVER_CFLAGS='-Werror'
 
   build-32bit:
     runs-on: ubuntu-latest

src/Makefile

@@ -98,15 +98,6 @@ ifeq ($(USE_JEMALLOC),no)
 	MALLOC=libc
 endif
 
-# Some unit tests compile files a second time to get access to static functions, the "--allow-multiple-definition" flag
-# allows us to do that without an error, by using the first instance of function. This behavior can also be used
-# to tweak behavior of code just for unit tests. The version of ld on MacOS apparently always does this.
-ifneq ($(uname_S),Darwin)
-	ALLOW_DUPLICATE_FLAG=-Wl,--allow-multiple-definition
-else
-	ALLOW_DUPLICATE_FLAG=
-endif
-
 ifdef SANITIZER
 ifeq ($(SANITIZER),address)
 	MALLOC=libc
@@ -494,7 +485,7 @@ $(ENGINE_LIB_NAME): $(ENGINE_SERVER_OBJ)
 
 # valkey-unit-tests
 $(ENGINE_UNIT_TESTS): $(ENGINE_TEST_OBJ) $(ENGINE_LIB_NAME)
-	$(SERVER_LD) $(ALLOW_DUPLICATE_FLAG) -o $@ $^ ../deps/hiredis/libhiredis.a ../deps/lua/src/liblua.a ../deps/hdr_histogram/libhdrhistogram.a ../deps/fpconv/libfpconv.a $(FINAL_LIBS)
+	$(SERVER_LD) -o $@ $^ ../deps/hiredis/libhiredis.a ../deps/lua/src/liblua.a ../deps/hdr_histogram/libhdrhistogram.a ../deps/fpconv/libfpconv.a $(FINAL_LIBS)
 
 # valkey-sentinel
 $(ENGINE_SENTINEL_NAME): $(SERVER_NAME)

src/debug.c

@@ -1023,7 +1023,7 @@ void debugCommand(client *c) {
 
 /* =========================== Crash handling  ============================== */
 
-__attribute__((noinline)) void _serverAssert(const char *estr, const char *file, int line) {
+__attribute__((noinline, weak)) void _serverAssert(const char *estr, const char *file, int line) {
     int new_report = bugReportStart();
     serverLog(LL_WARNING, "=== %sASSERTION FAILED ===", new_report ? "" : "RECURSIVE ");
     serverLog(LL_WARNING, "==> %s:%d '%s' is not true", file, line, estr);

src/server.c

@@ -6810,7 +6810,8 @@ serverTestProc *getTestProcByName(const char *name) {
 }
 #endif
 
-int main(int argc, char **argv) {
+/* Main is marked as weak so that unit tests can use their own main function. */
+__attribute__((weak)) int main(int argc, char **argv) {
     struct timeval tv;
     int j;
     char config_from_stdin = 0;