From 7cec716420b0f0bfbec8a827955d810b0f9804ab Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 19 Oct 2023 10:42:06 -0700
Subject: [PATCH] Remove reliance on Spanned for Member

---
 impl/src/expand.rs | 18 +++++++++---------
 impl/src/lib.rs    |  1 +
 impl/src/prop.rs   |  3 ++-
 impl/src/span.rs   | 15 +++++++++++++++
 4 files changed, 27 insertions(+), 10 deletions(-)
 create mode 100644 impl/src/span.rs

diff --git a/impl/src/expand.rs b/impl/src/expand.rs
index 394aafb..9124ca3 100644
--- a/impl/src/expand.rs
+++ b/impl/src/expand.rs
@@ -1,10 +1,10 @@
 use crate::ast::{Enum, Field, Input, Struct};
 use crate::attr::Trait;
 use crate::generics::InferredBounds;
+use crate::span::MemberSpan;
 use proc_macro2::TokenStream;
 use quote::{format_ident, quote, quote_spanned, ToTokens};
 use std::collections::BTreeSet as Set;
-use syn::spanned::Spanned;
 use syn::{
     Data, DeriveInput, GenericArgument, Member, PathArguments, Result, Token, Type, Visibility,
 };
@@ -39,7 +39,7 @@ fn impl_struct(input: Struct) -> TokenStream {
             error_inferred_bounds.insert(ty, quote!(std::error::Error + 'static));
         }
         let asref = if type_is_option(source_field.ty) {
-            Some(quote_spanned!(source.span()=> .as_ref()?))
+            Some(quote_spanned!(source.member_span()=> .as_ref()?))
         } else {
             None
         };
@@ -67,13 +67,13 @@ fn impl_struct(input: Struct) -> TokenStream {
         let body = if let Some(source_field) = input.source_field() {
             let source = &source_field.member;
             let source_provide = if type_is_option(source_field.ty) {
-                quote_spanned! {source.span()=>
+                quote_spanned! {source.member_span()=>
                     if let ::core::option::Option::Some(source) = &self.#source {
                         source.thiserror_provide(#request);
                     }
                 }
             } else {
-                quote_spanned! {source.span()=>
+                quote_spanned! {source.member_span()=>
                     self.#source.thiserror_provide(#request);
                 }
             };
@@ -214,7 +214,7 @@ fn impl_enum(input: Enum) -> TokenStream {
                     error_inferred_bounds.insert(ty, quote!(std::error::Error + 'static));
                 }
                 let asref = if type_is_option(source_field.ty) {
-                    Some(quote_spanned!(source.span()=> .as_ref()?))
+                    Some(quote_spanned!(source.member_span()=> .as_ref()?))
                 } else {
                     None
                 };
@@ -256,13 +256,13 @@ fn impl_enum(input: Enum) -> TokenStream {
                     let source = &source_field.member;
                     let varsource = quote!(source);
                     let source_provide = if type_is_option(source_field.ty) {
-                        quote_spanned! {source.span()=>
+                        quote_spanned! {source.member_span()=>
                             if let ::core::option::Option::Some(source) = #varsource {
                                 source.thiserror_provide(#request);
                             }
                         }
                     } else {
-                        quote_spanned! {source.span()=>
+                        quote_spanned! {source.member_span()=>
                             #varsource.thiserror_provide(#request);
                         }
                     };
@@ -295,13 +295,13 @@ fn impl_enum(input: Enum) -> TokenStream {
                     let backtrace = &backtrace_field.member;
                     let varsource = quote!(source);
                     let source_provide = if type_is_option(source_field.ty) {
-                        quote_spanned! {backtrace.span()=>
+                        quote_spanned! {backtrace.member_span()=>
                             if let ::core::option::Option::Some(source) = #varsource {
                                 source.thiserror_provide(#request);
                             }
                         }
                     } else {
-                        quote_spanned! {backtrace.span()=>
+                        quote_spanned! {backtrace.member_span()=>
                             #varsource.thiserror_provide(#request);
                         }
                     };
diff --git a/impl/src/lib.rs b/impl/src/lib.rs
index c5dab93..683c8fb 100644
--- a/impl/src/lib.rs
+++ b/impl/src/lib.rs
@@ -22,6 +22,7 @@ mod expand;
 mod fmt;
 mod generics;
 mod prop;
+mod span;
 mod valid;
 
 use proc_macro::TokenStream;
diff --git a/impl/src/prop.rs b/impl/src/prop.rs
index e4d2f18..5a6a6bc 100644
--- a/impl/src/prop.rs
+++ b/impl/src/prop.rs
@@ -1,4 +1,5 @@
 use crate::ast::{Enum, Field, Struct, Variant};
+use crate::span::MemberSpan;
 use proc_macro2::Span;
 use syn::spanned::Spanned;
 use syn::{Member, Type};
@@ -79,7 +80,7 @@ impl Field<'_> {
         } else if let Some(from_attr) = &self.attrs.from {
             from_attr.path().span()
         } else {
-            self.member.span()
+            self.member.member_span()
         }
     }
 }
diff --git a/impl/src/span.rs b/impl/src/span.rs
new file mode 100644
index 0000000..c1237dd
--- /dev/null
+++ b/impl/src/span.rs
@@ -0,0 +1,15 @@
+use proc_macro2::Span;
+use syn::Member;
+
+pub trait MemberSpan {
+    fn member_span(&self) -> Span;
+}
+
+impl MemberSpan for Member {
+    fn member_span(&self) -> Span {
+        match self {
+            Member::Named(ident) => ident.span(),
+            Member::Unnamed(index) => index.span,
+        }
+    }
+}