From ea408f7ab617cd210c3704bdb75b064722f13c57 Mon Sep 17 00:00:00 2001
From: Diggory Blake <diggsey@googlemail.com>
Date: Fri, 22 Oct 2021 15:01:40 +0100
Subject: [PATCH] Avoid parsing function bodies for a better rust-analyzer
 experience.

---
 Cargo.toml               |  4 ++--
 sqlxmq_macros/Cargo.toml |  7 +++---
 sqlxmq_macros/src/lib.rs | 48 ++++++++++++++++++++++++++++++++++++----
 3 files changed, 50 insertions(+), 9 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 6740ce3..763ff00 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "sqlxmq"
-version = "0.3.2"
+version = "0.3.3"
 authors = ["Diggory Blake <diggsey@googlemail.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -23,7 +23,7 @@ uuid = { version = "0.8.2", features = ["v4"] }
 log = "0.4.14"
 serde_json = "1.0.64"
 serde = "1.0.124"
-sqlxmq_macros = { version = "0.3.2", path = "sqlxmq_macros" }
+sqlxmq_macros = { version = "0.3.3", path = "sqlxmq_macros" }
 anymap2 = "0.13.0"
 
 [features]
diff --git a/sqlxmq_macros/Cargo.toml b/sqlxmq_macros/Cargo.toml
index 6b904e5..c53035e 100644
--- a/sqlxmq_macros/Cargo.toml
+++ b/sqlxmq_macros/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "sqlxmq_macros"
-version = "0.3.2"
+version = "0.3.3"
 authors = ["Diggory Blake <diggsey@googlemail.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -14,5 +14,6 @@ documentation = "https://docs.rs/sqlxmq"
 proc-macro = true
 
 [dependencies]
-syn = { version = "1.0.64", features = ["full"] }
-quote = "1.0.9"
+syn = { version = "1.0.80", features = ["full"] }
+quote = "1.0.10"
+proc-macro2 = "1.0.30"
diff --git a/sqlxmq_macros/src/lib.rs b/sqlxmq_macros/src/lib.rs
index f21071a..b0452ad 100644
--- a/sqlxmq_macros/src/lib.rs
+++ b/sqlxmq_macros/src/lib.rs
@@ -6,10 +6,12 @@
 use std::mem;
 
 use proc_macro::TokenStream;
-use quote::quote;
+use proc_macro2::TokenStream as TokenStream2;
+use quote::{quote, ToTokens, TokenStreamExt};
 use syn::{
-    parse_macro_input, parse_quote, AttributeArgs, Error, ItemFn, Lit, Meta, NestedMeta, Path,
-    Result, Visibility,
+    parse::{Parse, ParseStream},
+    parse_macro_input, parse_quote, AttrStyle, Attribute, AttributeArgs, Error, Lit, Meta,
+    NestedMeta, Path, Result, Signature, Visibility,
 };
 
 #[derive(Default)]
@@ -90,6 +92,44 @@ fn interpret_job_arg(options: &mut JobOptions, arg: NestedMeta) -> Result<()> {
     Ok(())
 }
 
+#[derive(Clone)]
+struct MaybeItemFn {
+    attrs: Vec<Attribute>,
+    vis: Visibility,
+    sig: Signature,
+    block: TokenStream2,
+}
+
+/// This parses a `TokenStream` into a `MaybeItemFn`
+/// (just like `ItemFn`, but skips parsing the body).
+impl Parse for MaybeItemFn {
+    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+        let attrs = input.call(syn::Attribute::parse_outer)?;
+        let vis: Visibility = input.parse()?;
+        let sig: Signature = input.parse()?;
+        let block: TokenStream2 = input.parse()?;
+        Ok(Self {
+            attrs,
+            vis,
+            sig,
+            block,
+        })
+    }
+}
+
+impl ToTokens for MaybeItemFn {
+    fn to_tokens(&self, tokens: &mut TokenStream2) {
+        tokens.append_all(
+            self.attrs
+                .iter()
+                .filter(|attr| matches!(attr.style, AttrStyle::Outer)),
+        );
+        self.vis.to_tokens(tokens);
+        self.sig.to_tokens(tokens);
+        self.block.to_tokens(tokens);
+    }
+}
+
 /// Marks a function as being a background job.
 ///
 /// The first argument to the function must have type `CurrentJob`.
@@ -181,7 +221,7 @@ fn interpret_job_arg(options: &mut JobOptions, arg: NestedMeta) -> Result<()> {
 #[proc_macro_attribute]
 pub fn job(attr: TokenStream, item: TokenStream) -> TokenStream {
     let args = parse_macro_input!(attr as AttributeArgs);
-    let mut inner_fn = parse_macro_input!(item as ItemFn);
+    let mut inner_fn = parse_macro_input!(item as MaybeItemFn);
 
     let mut options = JobOptions::default();
     let mut errors = Vec::new();