fix: make tests green with the race detector

Author: dunglas

.github/workflows/tests.yaml

@@ -56,4 +56,4 @@ jobs:
         env:
           PKG_CONFIG_PATH: ${{ github.workspace }}/fswatch/target/lib/pkgconfig
           LD_LIBRARY_PATH: ${{ github.workspace }}/fswatch/target/lib
-        run: go test
+        run: go test -race

fswatch.c

@@ -1,8 +1,11 @@
 #include "fswatch.h"
 #include "_cgo_export.h"
-#include <stdint.h>
 
-void process_events(fsw_cevent const *const events,
-                    const unsigned int event_num, void *data) {
+static inline void process_events(fsw_cevent const *const events,
+                           const unsigned int event_num, void *data) {
   go_callback((fsw_cevent *)events, event_num, (uintptr_t)data);
-}
+}
+
+void set_callback(const FSW_HANDLE handle, uintptr_t data) {
+  fsw_set_callback(handle, process_events, (void *)data);
+}

fswatch.go

@@ -2,6 +2,7 @@
 package fswatch
 
 // #cgo pkg-config: libfswatch
+// #cgo CFLAGS: -Wall -Werror
 // #include <stdint.h>
 // #include <stdlib.h>
 // #include <libfswatch/c/libfswatch.h>
@@ -139,7 +140,7 @@ func NewSession(paths []string, c Callback, options ...Option) (*Session, error)
 	h := cgo.NewHandle(s)
 	s.callback = c
 	s.cgoHandle = h
-	C.fsw_set_callback(s.handle, C.FSW_CEVENT_CALLBACK(C.process_events), unsafe.Pointer(h)) //nolint:unsafeptr
+	C.set_callback(s.handle, C.uintptr_t(h))
 
 	return s, nil
 }

fswatch.h

@@ -1,4 +1,4 @@
+#include <stdint.h>
 #include <libfswatch/c/libfswatch.h>
 
-void process_events(fsw_cevent const *const events,
-                    const unsigned int event_num, void *data);
+void set_callback(const FSW_HANDLE handle, uintptr_t data);