replace maybe_unused

Summary:
Genna spotted a couple of these in  D61724164. `unused_parameter` is a custom
Watchman macro for unused parameters. Now there is maybe_unused and that is
more standard so let's swap these out.

Reviewed By: jdelliot

Differential Revision: D62314836

fbshipit-source-id: ff10c155b4277716a0ef1893a149dbddc68765f9

watchman/fs/FSDetect.cpp

@@ -31,15 +31,13 @@ using namespace watchman;
 
 namespace watchman {
 
-CaseSensitivity getCaseSensitivityForPath(const char* path) {
+CaseSensitivity getCaseSensitivityForPath([[maybe_unused]] const char* path) {
 #ifdef __APPLE__
   return pathconf(path, _PC_CASE_SENSITIVE) ? CaseSensitivity::CaseSensitive
                                             : CaseSensitivity::CaseInSensitive;
 #elif defined(_WIN32)
-  unused_parameter(path);
   return CaseSensitivity::CaseInSensitive;
 #else
-  unused_parameter(path);
   return CaseSensitivity::CaseSensitive;
 #endif
 }
@@ -122,7 +120,7 @@ w_string w_fstype_detect_macos_nfs(w_string fstype, w_string edenfs_indicator) {
 // need to have a fully comprehensive mapping of the underlying filesystem
 // type codes to names, just the known problematic types
 
-w_string w_fstype(const char* path) {
+w_string w_fstype([[maybe_unused]] const char* path) {
 #ifdef __linux__
   // If possible, we prefer to read the filesystem type names from
   // `/proc/self/mounts`
@@ -213,7 +211,6 @@ w_string w_fstype(const char* path) {
   }
   return w_string("unknown", W_STRING_UNICODE);
 #else
-  unused_parameter(path);
   return w_string("unknown", W_STRING_UNICODE);
 #endif
 }

watchman/saved_state/SavedStateFactory.cpp

@@ -21,12 +21,9 @@ std::unique_ptr<SavedStateInterface> getInterface(
     w_string_piece storageType,
     const json_ref& savedStateConfig,
     const SCM* scm,
-    Configuration config,
-    std::function<void(RootMetadata&)> collectRootMetadata,
-    ClientContext clientInfo) {
-  unused_parameter(config);
-  unused_parameter(collectRootMetadata);
-  unused_parameter(clientInfo);
+    [[maybe_unused]] Configuration config,
+    [[maybe_unused]] std::function<void(RootMetadata&)> collectRootMetadata,
+    [[maybe_unused]] ClientContext clientInfo) {
 #if HAVE_MANIFOLD
   if (storageType == "manifold") {
     return std::make_unique<ManifoldSavedStateInterface>(

watchman/watchman_system.h

@@ -204,9 +204,6 @@ char* realpath(const char* filename, char* target);
 #define ignore_result(x) x
 #endif
 
-// self-documenting hint to the compiler that we didn't use it
-#define unused_parameter(x) (void)x
-
 #ifdef __cplusplus
 extern "C" {
 #endif