Support gz compressed AST input

macro/Cargo.toml

@@ -15,7 +15,7 @@ categories = ["development-tools::ffi"]
 proc-macro = true
 
 [features]
-experimental = ["clang-ast", "memmap", "serde", "serde_json"]
+experimental = ["clang-ast", "flate2", "memmap", "serde", "serde_json"]
 
 [dependencies]
 proc-macro2 = "1.0"
@@ -24,6 +24,7 @@ syn = { version = "1.0.70", features = ["full"] }
 
 # optional dependencies
 clang-ast = { version = "0.1", optional = true }
+flate2 = { version = "1.0", optional = true }
 memmap = { version = "0.7", optional = true }
 serde = { version = "1.0", optional = true, features = ["derive"] }
 serde_json = { version = "1.0", optional = true }

macro/src/clang.rs

@@ -2,13 +2,15 @@ use crate::syntax::attrs::OtherAttrs;
 use crate::syntax::namespace::Namespace;
 use crate::syntax::report::Errors;
 use crate::syntax::{Api, Discriminant, Doc, Enum, EnumRepr, ForeignName, Pair, Variant};
+use flate2::write::GzDecoder;
 use memmap::Mmap;
 use proc_macro2::{Delimiter, Group, Ident, TokenStream};
 use quote::{format_ident, quote, quote_spanned};
 use serde::Deserialize;
 use std::env;
 use std::fmt::{self, Display};
 use std::fs::File;
+use std::io::Write;
 use std::path::PathBuf;
 use std::str::FromStr;
 use syn::{parse_quote, Path};
@@ -91,16 +93,29 @@ pub fn load(cx: &mut Errors, apis: &mut [Api]) {
         }
     };
 
-    let ast_dump_bytes =
-        match File::open(&ast_dump_path).and_then(|file| unsafe { Mmap::map(&file) }) {
-            Ok(memmap) => memmap,
-            Err(error) => {
-                let msg = format!("failed to read {}: {}", ast_dump_path.display(), error);
-                return cx.error(span, msg);
+    let memmap = File::open(&ast_dump_path).and_then(|file| unsafe { Mmap::map(&file) });
+    let mut gunzipped;
+    let ast_dump_bytes = match match memmap {
+        Ok(ref memmap) => {
+            let is_gzipped = memmap.get(..2) == Some(b"\x1f\x8b");
+            if is_gzipped {
+                gunzipped = Vec::new();
+                let decode_result = GzDecoder::new(&mut gunzipped).write_all(&memmap);
+                decode_result.map(|_| gunzipped.as_slice())
+            } else {
+                Ok(&memmap as &[u8])
             }
-        };
+        }
+        Err(error) => Err(error),
+    } {
+        Ok(bytes) => bytes,
+        Err(error) => {
+            let msg = format!("failed to read {}: {}", ast_dump_path.display(), error);
+            return cx.error(span, msg);
+        }
+    };
 
-    let ref root: Node = match serde_json::from_slice(&ast_dump_bytes) {
+    let ref root: Node = match serde_json::from_slice(ast_dump_bytes) {
         Ok(root) => root,
         Err(error) => {
             let msg = format!("failed to read {}: {}", ast_dump_path.display(), error);