Use differently named __private module per patch release

serde_core/build.rs

@@ -1,13 +1,28 @@
 use std::env;
+use std::fs;
+use std::path::PathBuf;
 use std::process::Command;
 use std::str;
 
+const PRIVATE: &str = "\
+#[doc(hidden)]
+pub mod __private$$ {
+    #[doc(hidden)]
+    pub use crate::private::*;
+}
+";
+
 // The rustc-cfg strings below are *not* public API. Please let us know by
 // opening a GitHub issue if your build environment requires some way to enable
 // these cfgs other than by executing our build script.
 fn main() {
     println!("cargo:rerun-if-changed=build.rs");
 
+    let out_dir = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    let patch_version = env::var("CARGO_PKG_VERSION_PATCH").unwrap();
+    let module = PRIVATE.replace("$$", &patch_version);
+    fs::write(out_dir.join("private.rs"), module).unwrap();
+
     let minor = match rustc_minor_version() {
         Some(minor) => minor,
         None => return,