derive: Shrink dependency list

askama_derive/Cargo.toml

@@ -34,8 +34,7 @@ with-warp = []
 mime = "0.3"
 mime_guess = "2"
 nom = "7"
-proc-macro2 = "1"
-quote = "1"
+quote = { version = "1", default-features = false }
 serde = { version = "1.0", optional = true, features = ["derive"] }
-syn = "1"
+syn = { version = "1", default-features = false }
 toml_edit = { version = "0.19", optional = true, features = ["serde"] }

askama_derive/src/generator.rs

@@ -463,7 +463,7 @@ impl<'a> Generator<'a> {
         let mut where_clause = match where_clause {
             Some(clause) => clause.clone(),
             None => syn::WhereClause {
-                where_token: syn::Token![where](proc_macro2::Span::call_site()),
+                where_token: syn::token::Where::default(),
                 predicates: syn::punctuated::Punctuated::new(),
             },
         };
@@ -500,8 +500,7 @@ impl<'a> Generator<'a> {
     // Implement Rocket's `Responder`.
     #[cfg(feature = "with-rocket")]
     fn impl_rocket_responder(&mut self, buf: &mut Buffer) -> Result<(), CompileError> {
-        let lifetime = syn::Lifetime::new("'askama", proc_macro2::Span::call_site());
-        let param = syn::GenericParam::Lifetime(syn::LifetimeDef::new(lifetime));
+        let param = syn::parse_quote!('askama);
         self.write_header(
             buf,
             "::askama_rocket::Responder<'askama, 'askama>",

askama_derive/src/lib.rs

@@ -6,7 +6,6 @@ use std::borrow::Cow;
 use std::fmt;
 
 use proc_macro::TokenStream;
-use proc_macro2::Span;
 
 mod config;
 mod generator;
@@ -22,21 +21,21 @@ pub fn derive_template(input: TokenStream) -> TokenStream {
 #[derive(Debug, Clone)]
 struct CompileError {
     msg: Cow<'static, str>,
-    span: Span,
 }
 
 impl CompileError {
-    fn new<S: Into<Cow<'static, str>>>(s: S, span: Span) -> Self {
+    fn new(s: impl Into<Cow<'static, str>>) -> Self {
         Self {
             msg: s.into(),
-            span,
         }
     }
 
     fn into_compile_error(self) -> TokenStream {
-        syn::Error::new(self.span, self.msg)
-            .to_compile_error()
-            .into()
+        let msg = &*self.msg;
+        quote::quote! {
+            ::core::compile_error!(#msg);
+        }
+        .into()
     }
 }
 
@@ -52,14 +51,14 @@ impl fmt::Display for CompileError {
 impl From<&'static str> for CompileError {
     #[inline]
     fn from(s: &'static str) -> Self {
-        Self::new(s, Span::call_site())
+        Self::new(s)
     }
 }
 
 impl From<String> for CompileError {
     #[inline]
     fn from(s: String) -> Self {
-        Self::new(s, Span::call_site())
+        Self::new(s)
     }
 }