Restrict only Default::default and Foo::default

Author: WeiTheShinobi

clippy_lints/src/lib.rs

@@ -985,6 +985,6 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(move |_| Box::new(non_std_lazy_statics::NonStdLazyStatic::new(conf)));
     store.register_late_pass(|_| Box::new(manual_option_as_slice::ManualOptionAsSlice::new(conf)));
     store.register_late_pass(|_| Box::new(single_option_map::SingleOptionMap));
-    store.register_early_pass(|| Box::new(struct_fields_rest_default::StructFieldsDefault));
+    store.register_late_pass(|_| Box::new(struct_fields_rest_default::StructFieldsDefault));
     // add lints here, do not remove this comment, it's used in `new_lint`
 }

clippy_lints/src/struct_fields_rest_default.rs

@@ -1,16 +1,17 @@
 use clippy_utils::diagnostics::span_lint_and_help;
+use clippy_utils::path_def_id;
 use clippy_utils::source::snippet;
-use rustc_ast::Expr;
-use rustc_ast::ast::{ExprKind, StructRest};
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_hir::{ExprKind, StructTailExpr};
+use rustc_lint::{LateLintPass, LintContext};
 use rustc_session::declare_lint_pass;
+use rustc_span::sym;
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Check struct initialization uses `..base` pattern to skip rest of struct field initialization.
+    /// Check struct initialization uses `..*::default()` pattern to skip rest of struct field initialization.
     ///
     /// ### Why restrict this?
-    /// Using `..base` can hide field initialization when new fields are added to structs,
+    /// Using `..*::default()` can hide field initialization when new fields are added to structs,
     /// potentially leading to bugs where developers forget to explicitly set values for new fields.
     ///
     /// ### Example
@@ -54,11 +55,13 @@ declare_clippy_lint! {
 
 declare_lint_pass!(StructFieldsDefault => [STRUCT_FIELDS_REST_DEFAULT]);
 
-impl EarlyLintPass for StructFieldsDefault {
-    fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
+impl<'tcx> LateLintPass<'tcx> for StructFieldsDefault {
+    fn check_expr(&mut self, cx: &rustc_lint::LateContext<'tcx>, expr: &'tcx rustc_hir::Expr<'tcx>) {
         if !expr.span.in_external_macro(cx.sess().source_map())
-            && let ExprKind::Struct(struct_expr) = &expr.kind
-            && let StructRest::Base(base) = &struct_expr.rest
+            && let ExprKind::Struct(_, _, StructTailExpr::Base(base)) = &expr.kind
+            && let ExprKind::Call(func, _) = base.kind
+            && let Some(did) = path_def_id(cx, func)
+            && cx.tcx.is_diagnostic_item(sym::default_fn, did)
         {
             span_lint_and_help(
                 cx,

tests/ui/struct_fields_rest_default.rs

@@ -30,11 +30,11 @@ fn main() {
         //~^ struct_fields_rest_default
     };
 
+    // should not lint
     #[rustfmt::skip]
     let _ = Foo {
         a: 10,
         ..Foo::get_foo()
-        //~^ struct_fields_rest_default
     };
 
     // should not lint in external macro

tests/ui/struct_fields_rest_default.stderr

@@ -34,22 +34,5 @@ LL | |
 LL | |     };
    | |_____^
 
-error: should not use `..Foo::get_foo()` to omit rest of struct field initialization
-  --> tests/ui/struct_fields_rest_default.rs:36:11
-   |
-LL |         ..Foo::get_foo()
-   |           ^^^^^^^^^^^^^^
-   |
-help: each field's initial value should be explicitly specified
-  --> tests/ui/struct_fields_rest_default.rs:34:13
-   |
-LL |       let _ = Foo {
-   |  _____________^
-LL | |         a: 10,
-LL | |         ..Foo::get_foo()
-LL | |
-LL | |     };
-   | |_____^
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors