memory: Document new additions to memory.h

src/nvim/memory.c

@@ -49,7 +49,6 @@ MemRealloc mem_realloc = &realloc;
 #endif
 
 #ifdef EXITFREE
-/// Indicates that free_all_mem function was or is running
 bool entered_free_all_mem = false;
 #endif
 

src/nvim/memory.h

@@ -5,17 +5,34 @@
 #include <stddef.h>  // for size_t
 #include <time.h>    // for time_t
 
+/// `malloc()` function signature
 typedef void *(*MemMalloc)(size_t);
+
+/// `free()` function signature
 typedef void (*MemFree)(void *);
+
+/// `calloc()` function signature
 typedef void *(*MemCalloc)(size_t, size_t);
+
+/// `realloc()` function signature
 typedef void *(*MemRealloc)(void *, size_t);
 
+#ifdef UNIT_TESTING
+/// When unit testing: pointer to the `malloc()` function, may be altered
 extern MemMalloc mem_malloc;
+
+/// When unit testing: pointer to the `free()` function, may be altered
 extern MemFree mem_free;
+
+/// When unit testing: pointer to the `calloc()` function, may be altered
 extern MemCalloc mem_calloc;
+
+/// When unit testing: pointer to the `realloc()` function, may be altered
 extern MemRealloc mem_realloc;
+#endif
 
 #ifdef EXITFREE
+/// Indicates that free_all_mem function was or is running
 extern bool entered_free_all_mem;
 #endif