fix: don't drop leading comments in extern

Author: calebcartwright

src/items.rs

@@ -161,14 +161,6 @@ enum BodyElement<'a> {
     ForeignItem(&'a ast::ForeignItem),
 }
 
-impl BodyElement<'_> {
-    pub(crate) fn span(&self) -> Span {
-        match self {
-            BodyElement::ForeignItem(fi) => fi.span(),
-        }
-    }
-}
-
 /// Represents a fn's signature.
 pub(crate) struct FnSig<'a> {
     decl: &'a ast::FnDecl,
@@ -277,9 +269,6 @@ impl<'a> FmtVisitor<'a> {
             self.block_indent = self.block_indent.block_indent(self.config);
 
             if !item.body.is_empty() {
-                // Advance to first item (statement or inner attribute)
-                // within the block.
-                self.last_pos = item.body[0].span().lo();
                 for item in &item.body {
                     self.format_body_element(item);
                 }

tests/source/issue_4528.rs

@@ -0,0 +1,8 @@
+#![allow(clippy::no_effect)]
+ 
+extern "C" {
+ // N.B., mutability can be easily incorrect in FFI calls -- as
+     // in C, the default is mutable pointers.
+    fn ffi(c: *mut u8);
+     fn int_ffi(c: *mut i32);
+}

tests/target/issue_4528.rs

@@ -0,0 +1,8 @@
+#![allow(clippy::no_effect)]
+
+extern "C" {
+    // N.B., mutability can be easily incorrect in FFI calls -- as
+    // in C, the default is mutable pointers.
+    fn ffi(c: *mut u8);
+    fn int_ffi(c: *mut i32);
+}