Revert to use item_fn.span()

Signed-off-by: Jiahao XU <[email protected]>

Author: NobodyXu

gix-macros/src/momo.rs

@@ -14,7 +14,7 @@ pub(crate) fn inner(code: proc_macro2::TokenStream) -> proc_macro2::TokenStream
         let (has_conversion_in_effect, argtypes, argexprs, has_self) = convert(&item_fn.sig.inputs, &ty_conversions);
         if !has_conversion_in_effect {
             return Error::new(
-                proc_macro2::Span::call_site(),
+                item_fn.span(),
                 "Couldn't apply a single conversion - momo is ineffective here",
             )
             .to_compile_error();

gix-macros/tests/momo/ux/error_if_ineffective.stderr

@@ -1,10 +1,8 @@
 error: Couldn't apply a single conversion - momo is ineffective here
- --> tests/momo/ux/error_if_ineffective.rs:2:1
+ --> tests/momo/ux/error_if_ineffective.rs:1:1
   |
-2 | #[gix_macros::momo]
-  | ^^^^^^^^^^^^^^^^^^^
-  |
-  = note: this error originates in the attribute macro `gix_macros::momo` (in Nightly builds, run with -Z macro-backtrace for more info)
+1 | /// If nothing is done, momo should fail.
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0601]: `main` function not found in crate `$CRATE`
  --> tests/momo/ux/error_if_ineffective.rs:3:13