From 3d559d8b4149b94db612520998a97876ac0a4c00 Mon Sep 17 00:00:00 2001
From: Michael Sproul <michael@sigmaprime.io>
Date: Sat, 28 Sep 2019 14:29:14 +1000
Subject: [PATCH] Robustify derive macro attribute parsing (#544)

Missing whitespace in the implementation of `TokenStream::to_string` on
beta and nightly was breaking our parsing of derive macro attributes.

This change makes the parser ignore whitespace, and should make the beta
and nightly builds succeed again.
---
 eth2/utils/compare_fields_derive/src/lib.rs | 10 ++++------
 eth2/utils/ssz_derive/src/lib.rs            | 18 ++++++------------
 eth2/utils/test_random_derive/src/lib.rs    |  9 +++------
 eth2/utils/tree_hash_derive/src/lib.rs      |  7 +++----
 4 files changed, 16 insertions(+), 28 deletions(-)

diff --git a/eth2/utils/compare_fields_derive/src/lib.rs b/eth2/utils/compare_fields_derive/src/lib.rs
index c4ca3d64c..15137efa3 100644
--- a/eth2/utils/compare_fields_derive/src/lib.rs
+++ b/eth2/utils/compare_fields_derive/src/lib.rs
@@ -6,12 +6,10 @@ use quote::quote;
 use syn::{parse_macro_input, DeriveInput};
 
 fn is_slice(field: &syn::Field) -> bool {
-    for attr in &field.attrs {
-        if attr.tts.to_string() == "( as_slice )" {
-            return true;
-        }
-    }
-    false
+    field.attrs.iter().any(|attr| {
+        attr.path.is_ident("compare_fields")
+            && attr.tts.to_string().replace(" ", "") == "(as_slice)"
+    })
 }
 
 #[proc_macro_derive(CompareFields, attributes(compare_fields))]
diff --git a/eth2/utils/ssz_derive/src/lib.rs b/eth2/utils/ssz_derive/src/lib.rs
index 5bdb9ca9d..bd367e039 100644
--- a/eth2/utils/ssz_derive/src/lib.rs
+++ b/eth2/utils/ssz_derive/src/lib.rs
@@ -53,12 +53,9 @@ fn get_serializable_field_types<'a>(struct_data: &'a syn::DataStruct) -> Vec<&'a
 ///
 /// The field attribute is: `#[ssz(skip_serializing)]`
 fn should_skip_serializing(field: &syn::Field) -> bool {
-    for attr in &field.attrs {
-        if attr.tts.to_string() == "( skip_serializing )" {
-            return true;
-        }
-    }
-    false
+    field.attrs.iter().any(|attr| {
+        attr.path.is_ident("ssz") && attr.tts.to_string().replace(" ", "") == "(skip_serializing)"
+    })
 }
 
 /// Implements `ssz::Encode` for some `struct`.
@@ -149,12 +146,9 @@ pub fn ssz_encode_derive(input: TokenStream) -> TokenStream {
 ///
 /// The field attribute is: `#[ssz(skip_deserializing)]`
 fn should_skip_deserializing(field: &syn::Field) -> bool {
-    for attr in &field.attrs {
-        if attr.tts.to_string() == "( skip_deserializing )" {
-            return true;
-        }
-    }
-    false
+    field.attrs.iter().any(|attr| {
+        attr.path.is_ident("ssz") && attr.tts.to_string().replace(" ", "") == "(skip_deserializing)"
+    })
 }
 
 /// Implements `ssz::Decode` for some `struct`.
diff --git a/eth2/utils/test_random_derive/src/lib.rs b/eth2/utils/test_random_derive/src/lib.rs
index a268161dd..d6e3a0f95 100644
--- a/eth2/utils/test_random_derive/src/lib.rs
+++ b/eth2/utils/test_random_derive/src/lib.rs
@@ -9,12 +9,9 @@ use syn::{parse_macro_input, DeriveInput};
 ///
 /// The field attribute is: `#[test_random(default)]`
 fn should_use_default(field: &syn::Field) -> bool {
-    for attr in &field.attrs {
-        if attr.tts.to_string() == "( default )" {
-            return true;
-        }
-    }
-    false
+    field.attrs.iter().any(|attr| {
+        attr.path.is_ident("test_random") && attr.tts.to_string().replace(" ", "") == "(default)"
+    })
 }
 
 #[proc_macro_derive(TestRandom, attributes(test_random))]
diff --git a/eth2/utils/tree_hash_derive/src/lib.rs b/eth2/utils/tree_hash_derive/src/lib.rs
index c92595818..1e702c53c 100644
--- a/eth2/utils/tree_hash_derive/src/lib.rs
+++ b/eth2/utils/tree_hash_derive/src/lib.rs
@@ -31,10 +31,9 @@ fn get_hashable_named_field_idents<'a>(struct_data: &'a syn::DataStruct) -> Vec<
 ///
 /// The field attribute is: `#[tree_hash(skip_hashing)]`
 fn should_skip_hashing(field: &syn::Field) -> bool {
-    field
-        .attrs
-        .iter()
-        .any(|attr| attr.into_token_stream().to_string() == "# [ tree_hash ( skip_hashing ) ]")
+    field.attrs.iter().any(|attr| {
+        attr.path.is_ident("tree_hash") && attr.tts.to_string().replace(" ", "") == "(skip_hashing)"
+    })
 }
 
 /// Implements `tree_hash::TreeHash` for some `struct`.