Modernize imgui-sys-bindgen code slightly

imgui-sys-bindgen/Cargo.toml

@@ -2,6 +2,7 @@
 name = "imgui-sys-bindgen"
 version = "0.0.0"
 authors = ["Joonas Javanainen <joonas.javanainen@gmail.com>", "imgui-rs contributors"]
+edition = "2018"
 description = "imgui-sys bindings updater"
 homepage = "https://github.com/Gekkio/imgui-rs"
 repository = "https://github.com/Gekkio/imgui-rs"
@@ -10,7 +11,6 @@ publish = false
 
 [dependencies]
 bindgen = "0.53"
-failure = "0.1"
 serde = "1.0"
 serde_derive = "1.0"
 serde_json = "1.0"

imgui-sys-bindgen/src/lib.rs

@@ -1,17 +1,23 @@
-extern crate bindgen;
-#[macro_use]
-extern crate failure;
-#[macro_use]
-extern crate serde_derive;
-extern crate serde_json;
-
 use bindgen::{Bindings, EnumVariation, RustTarget};
-use failure::Error;
+use serde_derive::Deserialize;
 use std::collections::HashMap;
+use std::error::Error;
+use std::fmt;
 use std::fs::{read_to_string, File};
 use std::io::Read;
 use std::path::Path;
 
+#[derive(Debug)]
+struct BindgenError;
+
+impl fmt::Display for BindgenError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "Failed to generate bindings")
+    }
+}
+
+impl Error for BindgenError {}
+
 #[derive(Deserialize)]
 struct StructsAndEnums {
     enums: HashMap<String, serde_json::Value>,
@@ -38,17 +44,13 @@ struct Whitelist {
     definitions: Vec<String>,
 }
 
-fn only_key<K, V>((key, _): (K, V)) -> K {
-    key
-}
-
 fn parse_whitelist<R: Read>(
     structs_and_enums: R,
     definitions: R,
 ) -> Result<Whitelist, serde_json::Error> {
     let StructsAndEnums { enums, structs } = serde_json::from_reader(structs_and_enums)?;
-    let enums = enums.into_iter().map(only_key).collect();
-    let structs = structs.into_iter().map(only_key).collect();
+    let enums = enums.keys().cloned().collect();
+    let structs = structs.keys().cloned().collect();
 
     let definitions: HashMap<String, Vec<Definition>> = serde_json::from_reader(definitions)?;
     let definitions = definitions
@@ -74,7 +76,7 @@ fn parse_whitelist<R: Read>(
 pub fn generate_bindings<P: AsRef<Path>>(
     path: &P,
     wasm_import_name: Option<String>,
-) -> Result<Bindings, Error> {
+) -> Result<Bindings, Box<dyn Error>> {
     let path = path.as_ref();
     let structs_and_enums = File::open(path.join("structs_and_enums.json"))?;
     let definitions = File::open(path.join("definitions.json"))?;
@@ -116,8 +118,6 @@ pub fn generate_bindings<P: AsRef<Path>>(
     for e in whitelist.definitions {
         builder = builder.whitelist_function(format!("^{}", e));
     }
-    let bindings = builder
-        .generate()
-        .map_err(|_| format_err!("Failed to generate bindings"))?;
+    let bindings = builder.generate().map_err(|_| BindgenError)?;
     Ok(bindings)
 }

imgui-sys-bindgen/src/main.rs

@@ -1,5 +1,3 @@
-extern crate imgui_sys_bindgen;
-
 use imgui_sys_bindgen::generate_bindings;
 use std::env;