Introduce deinitIfLive utility and integrate enhanced memory management

src/memory/util.zig

@@ -0,0 +1,27 @@
+const std = @import("std");
+
+/// Deinitializes `allocator` only if it is still live.
+///
+/// Pass a pointer to the original allocator owner, such as an
+/// `ArenaAllocator` or `DebugAllocator`.
+///
+/// If `live` is `true`, calls `allocator.deinit()` and then sets
+/// `live` to `false`, preventing a later cleanup path from attempting
+/// to deinitialize the same allocator again.
+///
+/// The return value of `deinit()` is discarded.
+pub fn deinitIfLive(allocator: anytype, live: *bool) void
+{
+    comptime
+    {
+        const T = @TypeOf(allocator);
+
+        if (@typeInfo(T) != .pointer) @compileError("deinitIfLive expects a pointer!");
+        if (T == std.mem.Allocator)   @compileError("deinitIfLive expects a pointer to an allocator owner, not std.mem.Allocator!");
+    }
+
+    if (live.*) {
+        _ = allocator.deinit();
+        live.* = false;
+    }
+}