transpile: prune_unwanted_decls only after setting prenamed_decls

Author: Rua

c2rust-transpile/src/c_ast/mod.rs

@@ -1153,6 +1153,14 @@ impl TypedAstContext {
             }
         }
 
+        // If a typedef names an anonymous decl, and that decl is wanted,
+        // then the typedef is also wanted.
+        for (&decl_id, &subdecl_id) in &self.prenamed_decls {
+            if wanted.contains(&subdecl_id) {
+                wanted.insert(decl_id);
+            }
+        }
+
         // Unset c_main if we are not retaining its declaration
         if let Some(main_id) = self.c_main {
             if !wanted.contains(&main_id) {

c2rust-transpile/src/translator/mod.rs

@@ -708,6 +708,10 @@ pub fn translate(
             None
         };
 
+        // Identify typedefs that name unnamed types and collapse the two declarations
+        // into a single name and declaration, eliminating the typedef altogether.
+        t.ast_context.set_prenamed_decls();
+
         // Headers often pull in declarations that are unused;
         // we simplify the translator output by omitting those.
         t.ast_context
@@ -737,10 +741,6 @@ pub fn translate(
             prefix_names(&mut t, prefix);
         }
 
-        // Identify typedefs that name unnamed types and collapse the two declarations
-        // into a single name and declaration, eliminating the typedef altogether.
-        t.ast_context.set_prenamed_decls();
-
         for (&decl_id, &subdecl_id) in &t.ast_context.prenamed_decls {
             if let CDeclKind::Typedef { ref name, .. } = t.ast_context[decl_id].kind {
                 t.type_converter