From ca4cf356157282f07c6a33e57bed78a55a53f2e7 Mon Sep 17 00:00:00 2001
From: jeff-k <jeff_k@fastmail.com>
Date: Sat, 14 Sep 2024 18:45:24 +0100
Subject: [PATCH] spanned compiler error when cfg features disable enum
 variants

---
 pyo3-macros-backend/src/pyclass.rs   |  7 +++++--
 tests/ui/invalid_pyclass_enum.stderr | 10 ++++------
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/pyo3-macros-backend/src/pyclass.rs b/pyo3-macros-backend/src/pyclass.rs
index e89435aaf0d..291aeb0125a 100644
--- a/pyo3-macros-backend/src/pyclass.rs
+++ b/pyo3-macros-backend/src/pyclass.rs
@@ -2444,6 +2444,8 @@ fn generate_cfg_check(variants: &[PyClassEnumUnitVariant<'_>], cls: &syn::Ident)
         let cfg_attrs = &variant.cfg_attrs;
 
         if cfg_attrs.is_empty() {
+            // There's at least one variant of the enum without cfg attributes,
+            // so the check is not necessary
             return quote! {};
         }
 
@@ -2455,9 +2457,10 @@ fn generate_cfg_check(variants: &[PyClassEnumUnitVariant<'_>], cls: &syn::Ident)
         }
     }
 
-    quote! {
+    quote_spanned! {
+        cls.span() =>
         #[cfg(all(#(#conditions),*))]
-        ::core::compile_error!(concat!("All variants of enum `", stringify!(#cls), "` have been disabled by cfg attributes"));
+        ::core::compile_error!(concat!("#[pyclass] can't be used on enums without any variants - all variants of enum `", stringify!(#cls), "` have been configured out by cfg attributes"));
     }
 }
 
diff --git a/tests/ui/invalid_pyclass_enum.stderr b/tests/ui/invalid_pyclass_enum.stderr
index 51e246cb812..80dc9539748 100644
--- a/tests/ui/invalid_pyclass_enum.stderr
+++ b/tests/ui/invalid_pyclass_enum.stderr
@@ -66,13 +66,11 @@ error: The `ord` option requires the `eq` option.
 83 | #[pyclass(ord)]
    |           ^^^
 
-error: All variants of enum `AllEnumVariantsDisabled` have been disabled by cfg attributes
-  --> tests/ui/invalid_pyclass_enum.rs:96:1
+error: #[pyclass] can't be used on enums without any variants - all variants of enum `AllEnumVariantsDisabled` have been configured out by cfg attributes
+  --> tests/ui/invalid_pyclass_enum.rs:98:6
    |
-96 | #[pyclass(eq)]
-   | ^^^^^^^^^^^^^^
-   |
-   = note: this error originates in the attribute macro `pyclass` (in Nightly builds, run with -Z macro-backtrace for more info)
+98 | enum AllEnumVariantsDisabled {
+   |      ^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0369]: binary operation `==` cannot be applied to type `&SimpleEqOptRequiresPartialEq`
   --> tests/ui/invalid_pyclass_enum.rs:31:11