diff --git a/core/codegen/Cargo.toml b/core/codegen/Cargo.toml
index 55e9a29a..942bc6be 100644
--- a/core/codegen/Cargo.toml
+++ b/core/codegen/Cargo.toml
@@ -17,8 +17,10 @@ proc-macro = true
 [dependencies]
 indexmap = "1.0"
 quote = "1.0"
-rocket_http = { version = "0.5.0-dev", path = "../http/" }
+syn = { version = "1.0.72", features = ["full", "visit", "visit-mut", "extra-traits"] }
+proc-macro2 = "1.0.27"
 devise = { git = "https://github.com/SergioBenitez/Devise.git", rev = "df00b5" }
+rocket_http = { version = "0.5.0-dev", path = "../http/" }
 unicode-xid = "0.2"
 glob = "0.3"
 
diff --git a/core/codegen/src/attribute/catch/mod.rs b/core/codegen/src/attribute/catch/mod.rs
index 5c41412f..f504f1bf 100644
--- a/core/codegen/src/attribute/catch/mod.rs
+++ b/core/codegen/src/attribute/catch/mod.rs
@@ -1,10 +1,10 @@
 mod parse;
 
 use devise::ext::SpanDiagnosticExt;
-use devise::{syn, Spanned, Result};
+use devise::{Spanned, Result};
+use proc_macro2::{TokenStream, Span};
 
 use crate::http_codegen::Optional;
-use crate::proc_macro2::{TokenStream, Span};
 use crate::syn_ext::ReturnTypeExt;
 use crate::exports::*;
 
diff --git a/core/codegen/src/attribute/catch/parse.rs b/core/codegen/src/attribute/catch/parse.rs
index 6ce31178..34125c9c 100644
--- a/core/codegen/src/attribute/catch/parse.rs
+++ b/core/codegen/src/attribute/catch/parse.rs
@@ -1,8 +1,8 @@
 use devise::ext::SpanDiagnosticExt;
-use devise::{syn, MetaItem, Spanned, Result, FromMeta, Diagnostic};
+use devise::{MetaItem, Spanned, Result, FromMeta, Diagnostic};
+use proc_macro2::TokenStream;
 
 use crate::{http, http_codegen};
-use crate::proc_macro2::TokenStream;
 
 /// This structure represents the parsed `catch` attribute and associated items.
 pub struct Attribute {
diff --git a/core/codegen/src/attribute/entry/launch.rs b/core/codegen/src/attribute/entry/launch.rs
index c754a73a..09a40160 100644
--- a/core/codegen/src/attribute/entry/launch.rs
+++ b/core/codegen/src/attribute/entry/launch.rs
@@ -1,8 +1,8 @@
 use super::EntryAttr;
 
-use devise::{syn, Spanned, Result};
+use devise::{Spanned, Result};
 use devise::ext::SpanDiagnosticExt;
-use devise::proc_macro2::{TokenStream, Span};
+use proc_macro2::{TokenStream, Span};
 
 /// `#[rocket::launch]`: generates a `main` function that calls the attributed
 /// function to generate a `Rocket` instance. Then calls `.launch()` on the
diff --git a/core/codegen/src/attribute/entry/main.rs b/core/codegen/src/attribute/entry/main.rs
index e83261e6..52287b56 100644
--- a/core/codegen/src/attribute/entry/main.rs
+++ b/core/codegen/src/attribute/entry/main.rs
@@ -1,8 +1,8 @@
 use super::EntryAttr;
 
-use devise::{syn, Spanned, Result};
+use devise::{Spanned, Result};
 use devise::ext::SpanDiagnosticExt;
-use devise::proc_macro2::{TokenStream, Span};
+use proc_macro2::{TokenStream, Span};
 
 /// `#[rocket::async_main]`: calls the attributed fn inside `rocket::async_main`
 pub struct Main;
diff --git a/core/codegen/src/attribute/entry/mod.rs b/core/codegen/src/attribute/entry/mod.rs
index 0698ed83..38947777 100644
--- a/core/codegen/src/attribute/entry/mod.rs
+++ b/core/codegen/src/attribute/entry/mod.rs
@@ -2,9 +2,9 @@ mod main;
 mod launch;
 mod test;
 
-use devise::{syn, Diagnostic, Spanned, Result};
+use devise::{Diagnostic, Spanned, Result};
 use devise::ext::SpanDiagnosticExt;
-use devise::proc_macro2::{TokenStream, Span};
+use proc_macro2::{TokenStream, Span};
 
 // Common trait implemented by `async` entry generating attributes.
 trait EntryAttr {
diff --git a/core/codegen/src/attribute/entry/test.rs b/core/codegen/src/attribute/entry/test.rs
index 5804748d..8c197719 100644
--- a/core/codegen/src/attribute/entry/test.rs
+++ b/core/codegen/src/attribute/entry/test.rs
@@ -1,7 +1,7 @@
 use super::EntryAttr;
 
-use devise::{syn, Spanned, Result};
-use devise::proc_macro2::TokenStream;
+use devise::{Spanned, Result};
+use proc_macro2::TokenStream;
 
 /// `#[rocket::async_test]`: calls the attributed fn inside `rocket::async_test`
 pub struct Test;
diff --git a/core/codegen/src/attribute/param/guard.rs b/core/codegen/src/attribute/param/guard.rs
index 53396320..c972e6eb 100644
--- a/core/codegen/src/attribute/param/guard.rs
+++ b/core/codegen/src/attribute/param/guard.rs
@@ -1,13 +1,12 @@
 use std::hash::{Hash, Hasher};
 
-use devise::{syn, FromMeta, MetaItem, Result};
+use devise::{FromMeta, MetaItem, Result};
+use proc_macro2::Span;
 
 use crate::name::Name;
-use crate::proc_macro2::Span;
 use crate::proc_macro_ext::StringLit;
 use crate::http::uri;
 
-
 impl Dynamic {
     pub fn is_wild(&self) -> bool {
         self.value == "_"
diff --git a/core/codegen/src/attribute/param/mod.rs b/core/codegen/src/attribute/param/mod.rs
index 39442f4f..94e2c17e 100644
--- a/core/codegen/src/attribute/param/mod.rs
+++ b/core/codegen/src/attribute/param/mod.rs
@@ -3,7 +3,6 @@ mod parse;
 use std::ops::Deref;
 use std::hash::Hash;
 
-use crate::syn;
 use crate::name::Name;
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/core/codegen/src/attribute/param/parse.rs b/core/codegen/src/attribute/param/parse.rs
index 54eba8c4..e542cd41 100644
--- a/core/codegen/src/attribute/param/parse.rs
+++ b/core/codegen/src/attribute/param/parse.rs
@@ -1,9 +1,9 @@
 use unicode_xid::UnicodeXID;
 use devise::{Diagnostic, ext::SpanDiagnosticExt};
+use proc_macro2::Span;
 
 use crate::name::Name;
 use crate::proc_macro_ext::StringLit;
-use crate::proc_macro2::Span;
 use crate::attribute::param::{Parameter, Dynamic};
 use crate::http::uri::fmt::{Part, Kind, Path};
 
diff --git a/core/codegen/src/attribute/route/mod.rs b/core/codegen/src/attribute/route/mod.rs
index a24a2c43..5fae0b2a 100644
--- a/core/codegen/src/attribute/route/mod.rs
+++ b/core/codegen/src/attribute/route/mod.rs
@@ -2,11 +2,10 @@ mod parse;
 
 use std::hash::Hash;
 
-use proc_macro2::{TokenStream, Span};
 use devise::{Spanned, SpanWrapped, Result, FromMeta, Diagnostic};
 use devise::ext::TypeExt as _;
+use proc_macro2::{TokenStream, Span};
 
-use crate::{proc_macro2, syn};
 use crate::proc_macro_ext::StringLit;
 use crate::syn_ext::{IdentExt, TypeExt as _};
 use crate::http_codegen::{Method, Optional};
diff --git a/core/codegen/src/attribute/route/parse.rs b/core/codegen/src/attribute/route/parse.rs
index fadf7428..98d2191f 100644
--- a/core/codegen/src/attribute/route/parse.rs
+++ b/core/codegen/src/attribute/route/parse.rs
@@ -1,14 +1,13 @@
-use devise::{syn, Spanned, SpanWrapped, Result, FromMeta};
+use devise::{Spanned, SpanWrapped, Result, FromMeta};
 use devise::ext::{SpanDiagnosticExt, TypeExt};
 use indexmap::{IndexSet, IndexMap};
+use proc_macro2::Span;
 
 use crate::proc_macro_ext::Diagnostics;
 use crate::http_codegen::{Method, MediaType};
 use crate::attribute::param::{Parameter, Dynamic, Guard};
 use crate::syn_ext::FnArgExt;
-
 use crate::name::Name;
-use crate::proc_macro2::Span;
 use crate::http::ext::IntoOwned;
 use crate::http::uri::{Origin, fmt};
 
diff --git a/core/codegen/src/bang/export.rs b/core/codegen/src/bang/export.rs
index b48dd483..5004d17a 100644
--- a/core/codegen/src/bang/export.rs
+++ b/core/codegen/src/bang/export.rs
@@ -2,8 +2,7 @@ use std::hash::Hash;
 
 use devise::Spanned;
 use devise::ext::SpanDiagnosticExt;
-use devise::proc_macro2::{TokenStream, TokenTree, Punct};
-use devise::syn;
+use proc_macro2::{TokenStream, TokenTree, Punct};
 
 use crate::syn_ext::IdentExt;
 
diff --git a/core/codegen/src/bang/mod.rs b/core/codegen/src/bang/mod.rs
index 7dc7e35c..627ea338 100644
--- a/core/codegen/src/bang/mod.rs
+++ b/core/codegen/src/bang/mod.rs
@@ -1,8 +1,7 @@
 use devise::Result;
-
-use crate::syn::{Path, punctuated::Punctuated, parse::Parser, Token};
-use crate::proc_macro2::TokenStream;
-use crate::syn::spanned::Spanned;
+use syn::{Path, punctuated::Punctuated, parse::Parser, Token};
+use syn::spanned::Spanned;
+use proc_macro2::TokenStream;
 
 mod uri;
 mod uri_parsing;
diff --git a/core/codegen/src/bang/test_guide.rs b/core/codegen/src/bang/test_guide.rs
index ad2a609e..8de5b160 100644
--- a/core/codegen/src/bang/test_guide.rs
+++ b/core/codegen/src/bang/test_guide.rs
@@ -1,9 +1,9 @@
 use std::path::Path;
 use std::error::Error;
 
+use syn::{self, Ident, LitStr};
 use devise::ext::SpanDiagnosticExt;
-use devise::syn::{self, Ident, LitStr};
-use devise::proc_macro2::TokenStream;
+use proc_macro2::TokenStream;
 
 pub fn _macro(input: proc_macro::TokenStream) -> devise::Result<TokenStream> {
     let root_glob = syn::parse::<LitStr>(input.into())?;
diff --git a/core/codegen/src/bang/uri.rs b/core/codegen/src/bang/uri.rs
index a128679a..c8715fc1 100644
--- a/core/codegen/src/bang/uri.rs
+++ b/core/codegen/src/bang/uri.rs
@@ -1,14 +1,13 @@
 use std::fmt::Display;
 
-use devise::{syn, Result};
-use devise::ext::{SpanDiagnosticExt, quote_respanned};
+use devise::{Result, ext::{SpanDiagnosticExt, quote_respanned}};
+use syn::{Expr, Ident, Type, spanned::Spanned};
+use proc_macro2::TokenStream;
 
 use crate::http::uri::fmt;
 use crate::http_codegen::Optional;
-use crate::syn::{Expr, Ident, Type, spanned::Spanned};
 use crate::syn_ext::IdentExt;
 use crate::bang::uri_parsing::*;
-use crate::proc_macro2::TokenStream;
 use crate::attribute::param::Parameter;
 use crate::exports::*;
 use crate::URI_MACRO_PREFIX;
diff --git a/core/codegen/src/bang/uri_parsing.rs b/core/codegen/src/bang/uri_parsing.rs
index 88debbe0..3dd3d11e 100644
--- a/core/codegen/src/bang/uri_parsing.rs
+++ b/core/codegen/src/bang/uri_parsing.rs
@@ -3,15 +3,14 @@ use std::ops::Deref;
 use indexmap::IndexMap;
 use devise::{Spanned, ext::TypeExt};
 use quote::{ToTokens, TokenStreamExt};
+use syn::{Expr, Ident, LitStr, Path, Token, Type};
+use syn::parse::{self, Parse, ParseStream, Parser};
+use syn::punctuated::Punctuated;
+use proc_macro2::{TokenStream, TokenTree, Span};
 use rocket_http::uri::{Error, Reference};
 
-use crate::{http_codegen, syn::{self, Expr, Ident, LitStr, Path, Token, Type}};
-use crate::syn::parse::{self, Parse, ParseStream, Parser};
-use crate::syn::punctuated::Punctuated;
-
 use crate::http::uri::{Uri, Origin, Absolute, fmt};
 use crate::http::ext::IntoOwned;
-use crate::proc_macro2::{TokenStream, TokenTree, Span};
 use crate::proc_macro_ext::StringLit;
 use crate::attribute::param::{Parameter, Dynamic};
 use crate::name::Name;
@@ -549,7 +548,7 @@ impl Deref for UriLit {
 
 impl ToTokens for UriLit {
     fn to_tokens(&self, t: &mut TokenStream) {
-        use http_codegen::*;
+        use crate::http_codegen::*;
 
         let (uri, span) = (&self.0, self.1);
         match uri {
diff --git a/core/codegen/src/derive/form_field.rs b/core/codegen/src/derive/form_field.rs
index 3a701427..75a9bb64 100644
--- a/core/codegen/src/derive/form_field.rs
+++ b/core/codegen/src/derive/form_field.rs
@@ -2,8 +2,8 @@ use devise::{*, ext::{TypeExt, SpanDiagnosticExt}};
 
 use syn::visit_mut::VisitMut;
 use syn::visit::Visit;
+use proc_macro2::{TokenStream, TokenTree, Span};
 
-use crate::proc_macro2::{TokenStream, TokenTree, Span};
 use crate::syn_ext::IdentExt;
 use crate::name::Name;
 
diff --git a/core/codegen/src/derive/from_form.rs b/core/codegen/src/derive/from_form.rs
index 0834a38a..c334fd5d 100644
--- a/core/codegen/src/derive/from_form.rs
+++ b/core/codegen/src/derive/from_form.rs
@@ -1,7 +1,7 @@
 use devise::{*, ext::{TypeExt, SpanDiagnosticExt, GenericsExt, Split2, quote_respanned}};
+use proc_macro2::TokenStream;
 
 use crate::exports::*;
-use crate::proc_macro2::TokenStream;
 use crate::derive::form_field::{*, FieldName::*};
 
 // F: fn(field_ty: Ty, field_context: Expr)
diff --git a/core/codegen/src/derive/from_form_field.rs b/core/codegen/src/derive/from_form_field.rs
index 5fc5e4d6..a2bcba4e 100644
--- a/core/codegen/src/derive/from_form_field.rs
+++ b/core/codegen/src/derive/from_form_field.rs
@@ -1,7 +1,7 @@
 use devise::{*, ext::SpanDiagnosticExt};
+use proc_macro2::TokenStream;
 
 use crate::exports::*;
-use crate::proc_macro2::TokenStream;
 use crate::derive::form_field::{VariantExt, first_duplicate};
 
 pub fn derive_from_form_field(input: proc_macro::TokenStream) -> TokenStream {
diff --git a/core/codegen/src/derive/responder.rs b/core/codegen/src/derive/responder.rs
index 06d74150..d5b3a01d 100644
--- a/core/codegen/src/derive/responder.rs
+++ b/core/codegen/src/derive/responder.rs
@@ -1,8 +1,8 @@
 use quote::ToTokens;
 use devise::{*, ext::{TypeExt, SpanDiagnosticExt}};
+use proc_macro2::TokenStream;
 
 use crate::exports::*;
-use crate::proc_macro2::TokenStream;
 use crate::http_codegen::{ContentType, Status};
 
 #[derive(Debug, Default, FromMeta)]
diff --git a/core/codegen/src/derive/uri_display.rs b/core/codegen/src/derive/uri_display.rs
index 671b54dc..7dbe5e28 100644
--- a/core/codegen/src/derive/uri_display.rs
+++ b/core/codegen/src/derive/uri_display.rs
@@ -1,9 +1,8 @@
-
+use proc_macro2::TokenStream;
 use devise::{*, ext::SpanDiagnosticExt};
 
 use crate::exports::*;
 use crate::derive::form_field::{FieldExt, VariantExt};
-use crate::proc_macro2::TokenStream;
 use crate::http::uri::fmt;
 
 const NO_EMPTY_FIELDS: &str = "fieldless structs are not supported";
diff --git a/core/codegen/src/exports.rs b/core/codegen/src/exports.rs
index 4aa292fb..d6c1f4d9 100644
--- a/core/codegen/src/exports.rs
+++ b/core/codegen/src/exports.rs
@@ -1,6 +1,5 @@
-use crate::syn;
-use crate::proc_macro2::{Span, TokenStream};
-use crate::quote::{ToTokens, TokenStreamExt};
+use proc_macro2::{Span, TokenStream};
+use quote::{ToTokens, TokenStreamExt};
 
 #[derive(Debug, Copy, Clone)]
 pub struct StaticPath(pub Option<Span>, pub &'static str);
diff --git a/core/codegen/src/http_codegen.rs b/core/codegen/src/http_codegen.rs
index adb3a6c3..28418f59 100644
--- a/core/codegen/src/http_codegen.rs
+++ b/core/codegen/src/http_codegen.rs
@@ -1,8 +1,8 @@
 use quote::ToTokens;
 use devise::{FromMeta, MetaItem, Result, ext::{Split2, PathExt, SpanDiagnosticExt}};
+use proc_macro2::{TokenStream, Span};
 
 use crate::http;
-use crate::proc_macro2::{TokenStream, Span};
 
 #[derive(Debug)]
 pub struct ContentType(pub http::ContentType);
diff --git a/core/codegen/src/lib.rs b/core/codegen/src/lib.rs
index f55e2ed5..10d70a92 100644
--- a/core/codegen/src/lib.rs
+++ b/core/codegen/src/lib.rs
@@ -70,7 +70,6 @@ mod name;
 
 use crate::http::Method;
 use proc_macro::TokenStream;
-use devise::{proc_macro2, syn};
 
 static URI_MACRO_PREFIX: &str = "rocket_uri_macro_";
 static ROCKET_IDENT_PREFIX: &str = "__rocket_";
diff --git a/core/codegen/src/name.rs b/core/codegen/src/name.rs
index c478df01..d4902429 100644
--- a/core/codegen/src/name.rs
+++ b/core/codegen/src/name.rs
@@ -1,6 +1,7 @@
-use crate::syn::{self, Ident, ext::IdentExt};
 use crate::http::uncased::UncasedStr;
-use crate::proc_macro2::Span;
+
+use syn::{self, Ident, ext::IdentExt};
+use proc_macro2::{Span, TokenStream};
 
 /// A "name" read by codegen, which may or may not be an identifier. A `Name` is
 /// typically constructed indirectly via FromMeta, or From<Ident> or directly
@@ -55,7 +56,7 @@ impl devise::FromMeta for Name {
 }
 
 impl quote::ToTokens for Name {
-    fn to_tokens(&self, tokens: &mut devise::proc_macro2::TokenStream) {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
         syn::LitStr::new(self.as_str(), self.span()).to_tokens(tokens)
     }
 }
diff --git a/core/codegen/src/proc_macro_ext.rs b/core/codegen/src/proc_macro_ext.rs
index 32c13365..f5d4f85b 100644
--- a/core/codegen/src/proc_macro_ext.rs
+++ b/core/codegen/src/proc_macro_ext.rs
@@ -1,8 +1,7 @@
 use std::ops::RangeBounds;
 
 use devise::Diagnostic;
-
-use crate::proc_macro2::{Span, Literal};
+use proc_macro2::{Span, Literal};
 
 // An experiment.
 pub struct Diagnostics(Vec<Diagnostic>);
@@ -70,9 +69,9 @@ impl StringLit {
     }
 }
 
-impl crate::syn::parse::Parse for StringLit {
-    fn parse(input: devise::syn::parse::ParseStream<'_>) -> devise::syn::Result<Self> {
-        let lit = input.parse::<crate::syn::LitStr>()?;
+impl syn::parse::Parse for StringLit {
+    fn parse(input: syn::parse::ParseStream<'_>) -> syn::Result<Self> {
+        let lit = input.parse::<syn::LitStr>()?;
         Ok(StringLit::new(lit.value(), lit.span()))
     }
 }
diff --git a/core/codegen/src/syn_ext.rs b/core/codegen/src/syn_ext.rs
index 5e700cd2..41265581 100644
--- a/core/codegen/src/syn_ext.rs
+++ b/core/codegen/src/syn_ext.rs
@@ -3,8 +3,8 @@
 use std::ops::Deref;
 use std::hash::{Hash, Hasher};
 
-use crate::syn::{self, Ident, ext::IdentExt as _, visit::Visit};
-use crate::proc_macro2::Span;
+use syn::{self, Ident, ext::IdentExt as _, visit::Visit};
+use proc_macro2::{Span, TokenStream};
 
 pub trait IdentExt {
     fn prepend(&self, string: &str) -> syn::Ident;
@@ -19,7 +19,7 @@ pub trait ReturnTypeExt {
 }
 
 pub trait TokenStreamExt {
-    fn respanned(&self, span: crate::proc_macro2::Span) -> Self;
+    fn respanned(&self, span: Span) -> Self;
 }
 
 pub trait FnArgExt {
@@ -91,8 +91,8 @@ impl ReturnTypeExt for syn::ReturnType {
     }
 }
 
-impl TokenStreamExt for crate::proc_macro2::TokenStream {
-    fn respanned(&self, span: crate::proc_macro2::Span) -> Self {
+impl TokenStreamExt for TokenStream {
+    fn respanned(&self, span: Span) -> Self {
         self.clone().into_iter().map(|mut token| {
             token.set_span(span);
             token