fix: derivation of struct body span lo

Author: calebcartwright

src/formatting/items.rs

@@ -1388,7 +1388,12 @@ pub(crate) fn format_struct_struct(
     result.push_str(&header_str);
 
     let header_hi = struct_parts.ident.span.hi();
-    let body_lo = context.snippet_provider.span_after_last(span, "{");
+    let after_generics_span = struct_parts.generics.map_or(span, |generics| {
+        mk_sp(generics.where_clause.span.hi(), span.hi())
+    });
+    let body_lo = context
+        .snippet_provider
+        .span_after(after_generics_span, "{");
 
     let generics_str = match struct_parts.generics {
         Some(g) => format_generics(

tests/source/issue_4724.rs

@@ -0,0 +1 @@
+struct x{/** */#[x="{"]x:x}

tests/target/issue_4724.rs

@@ -0,0 +1,5 @@
+struct x {
+    /** */
+    #[x = "{"]
+    x: x,
+}