Code: Change mmap-rs flag to direct-mmap which disables it instead.

src-rust/Cargo.toml

@@ -19,7 +19,7 @@ no_format = [] # Removes string formatting (less detailed errors) for binary siz
 all_private = [] # No memory mapped files, memory is not shared.
 size_opt = ["nightly"]
 nightly = [] # Optimizations for nightly builds.
-mmap-rs = [] # Uses mmap-rs for memory mapping. This is auto activated during build.
+direct-mmap = [] # If set, uses built-in code for memory mapping. This is auto activated in build.rs for supported platforms.
 
 [dependencies]
 concat-string = "1.0.1"

src-rust/build.rs

@@ -1,11 +1,11 @@
 fn main() {
     // This defines a fallback to mmap-rs if one of the explicit memory mapped file implementations
     // is not available.
-    if !cfg!(any(
+    if cfg!(any(
         target_os = "macos",
         target_os = "windows",
         target_os = "linux"
     )) {
-        println!("cargo:rustc-cfg=feature=\"mmap-rs\"");
+        println!("cargo:rustc-cfg=feature=\"direct-mmap\"");
     }
 }

src-rust/src/internal/buffer_allocator.rs

@@ -22,7 +22,7 @@ pub fn allocate(
     return crate::internal::buffer_allocator_osx::allocate_osx(settings);
 
     // Fallback for non-hot-path OSes.
-    #[cfg(feature = "mmap-rs")]
+    #[cfg(not(feature = "direct-mmap"))]
     crate::internal::buffer_allocator_mmap_rs::allocate_mmap_rs(settings)
 }
 

src-rust/src/structs/private_allocation.rs

@@ -168,7 +168,7 @@ impl PrivateAllocation {
     }
 
     /// Frees the allocated memory when the `PrivateAllocation` instance is dropped.
-    #[cfg(feature = "mmap-rs")]
+    #[cfg(not(feature = "direct-mmap"))]
     pub(crate) fn drop_mmap_rs(&mut self) {
         use mmap_rs_with_map_from_existing::MmapOptions;
         let _map = unsafe {
@@ -196,7 +196,7 @@ impl Drop for PrivateAllocation {
         return PrivateAllocation::drop_macos(self);
 
         // non-hot-path-os
-        #[cfg(feature = "mmap-rs")]
+        #[cfg(not(feature = "direct-mmap"))]
         return PrivateAllocation::drop_mmap_rs(self);
     }
 }