Use our own proc-macro2 fork and don't allocate anything at release (somewhat)

Cargo.lock

@@ -38,9 +38,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.47"
+version = "2.0.48"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1726efe18f42ae774cc644f330953a5e7b3c3003d3edcecf18850fe9d4dd9afb"
+checksum = "0f3531638e407dfc0814761abb7c00a5b54992b849452a0646b7f65c9f770f3f"
 dependencies = [
  "proc-macro2",
  "quote",

README.md

@@ -4,11 +4,26 @@ A super simple file and directory embedding crate,
 that loads files from the filesystem in debug mode,
 allowing for quick edit-and-test cycles without compilation.
 
+It is also super efficient, and does not heap allocate when the
+files are embedded on release mode by utilizing `std::borrow::Cow`.
+
 On release mode it falls back to `include_str!`, `include_bytes!`
-and our own custom `include_dir!` implementation.
+and our own custom `include_dir!`-like implementation.
 
 ## Usage
 
+Add this to your Cargo.toml:
+
+```toml
+[dependencies]
+embed = { git = "https://github.com/RGBCube/embed-rs" }
+
+[patch.crates-io]
+proc-macro2 = { git = "https://github.com/RGBCube/proc-macro2" }
+```
+
+Then you can use this crate as so:
+
 ```rs
 let contents: Cow<'_, str> = embed::string!("path/to/file.txt");
 let bytes: Cow<'_, [u8]> = embed::bytes!("path/to/image.png");
@@ -17,6 +32,9 @@ let dir: embed::Dir = embed::dir!("path/to");
 let files: Vec<embed::File> = dir.flatten();
 ```
 
+I am not sure what name to publish this
+crate in, lmk if you find a good one.
+
 ## License
 
 ```

embed/src/lib.rs

@@ -1,5 +1,3 @@
-#![cfg(procmacro2_semver_exempt)]
-
 use std::{
     borrow::Cow,
     fs,
@@ -29,15 +27,13 @@ pub fn __string_runtime(neighbor: &str, path: &str) -> String {
 #[macro_export]
 macro_rules! string {
     ($path:literal) => {{
-        use ::std::borrow::Cow;
-
         #[cfg(debug_assertions)]
         {
-            Cow::Owned(::embed::__string_runtime(file!(), $path))
+            ::std::borrow::Cow::Owned(::embed::__string_runtime(file!(), $path))
         }
         #[cfg(not(debug_assertions))]
         {
-            Cow::Borrowed(include_str!($path))
+            ::std::borrow::Cow::Borrowed(include_str!($path))
         }
     }};
 }
@@ -90,7 +86,7 @@ pub enum DirEntry {
 #[derive(Debug, Clone)]
 pub struct Dir {
     /// The entries the directory houses.
-    pub children: Vec<DirEntry>,
+    pub children: Cow<'static, [DirEntry]>,
     /// The absolute path of the directory.
     pub path: Cow<'static, Path>,
 }
@@ -100,7 +96,8 @@ impl Dir {
     pub fn flatten(self) -> Vec<File> {
         let mut entries = Vec::new();
 
-        for child in self.children {
+        for child in self.children.into_owned() {
+            // TODO: Eliminate allocation.
             match child {
                 DirEntry::File(file) => entries.push(file),
                 DirEntry::Dir(dir) => entries.append(&mut dir.flatten()),
@@ -136,7 +133,7 @@ fn read_dir(directory: &Path) -> Vec<DirEntry> {
         );
 
         if filetype.is_dir() {
-            let children = read_dir(path.as_ref());
+            let children = Cow::Owned(read_dir(path.as_ref()));
 
             entries.push(DirEntry::Dir(Dir { children, path }))
         } else if filetype.is_file() {
@@ -161,8 +158,8 @@ pub fn __dir_runtime(neighbor: &str, path: &str) -> Dir {
     let children = read_dir(&directory);
 
     Dir {
-        children,
-        path: Cow::Owned(directory),
+        children: children.into(),
+        path: directory.into(),
     }
 }
 

embed_macros/Cargo.toml

@@ -16,3 +16,6 @@ proc-macro = true
 proc-macro2 = { version = "1", features = [ "span-locations" ] }
 quote       = "1"
 syn         = "2"
+
+[patch.crates-io]
+proc-macro2 = { git = "https://github.com/RGBCube/proc-macro2" }

embed_macros/src/lib.rs

@@ -1,5 +1,3 @@
-#![cfg(procmacro2_semver_exempt)]
-
 use std::{
     fs,
     path::PathBuf,
@@ -38,9 +36,10 @@ impl ToTokens for TokenVec {
     fn to_tokens(&self, tokens: &mut TokenStream) {
         let inner = &self.0;
 
-        tokens.extend(quote! {
-            vec![#(#inner),*]
-        });
+        tokens.extend(quote! {{
+            const CHILDREN: &[::embed::DirEntry] = &[#(#inner),*]; // FIXME: Not const.
+            ::std::borrow::Cow::Borrowed(CHILDREN)
+        }});
     }
 }