Start of doing a clean up of the notifier code.

This originated as trying to stop macOS builds from doing silly warnings during
a static build, but I noticed that there were common patterns that belong in
generic code instead of being repeated in each of the platform-specific pieces.

1 files changed, 24 insertions, 2 deletions

diff --git a/generic/tclInt.h b/generic/tclInt.h
index 1d192ff..4c3977a 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -5145,11 +5145,33 @@ typedef struct NRE_callback {
 #endif
 
 /*
+ * Special hack for macOS, where the static linker (technically the 'ar'
+ * command) hates empty object files, and accepts no flags to make it shut up.
+ *
+ * These symbols are otherwise completely useless.
+ *
+ * They can't be written to or written through. They can't be seen by any
+ * other code. They use a separate attribute (supported by all macOS
+ * compilers, which are derivatives of clang or gcc) to stop the compilation
+ * from moaning. They will be excluded during the final linking stage.
+ *
+ * Other platforms get nothing at all. That's good.
+ */
+
+#ifdef MAC_OSX_TCL
+#define TCL_MAC_EMPTY_FILE(name) \
+    static __attribute__((used)) const void *const TclUnusedFile_ ## name; \
+    static const void *const TclUnusedFile_ ## name = NULL;
+#else
+#define TCL_MAC_EMPTY_FILE(name)
+#endif /* MAC_OSX_TCL */
+
+/*
  * Other externals.
  */
 
-MODULE_SCOPE size_t TclEnvEpoch; /* Epoch of the tcl environment
-                                         * (if changed with tcl-env). */
+MODULE_SCOPE size_t TclEnvEpoch;	/* Epoch of the tcl environment
+					 * (if changed with tcl-env). */
 
 #endif /* _TCLINT */