only check main.rs and lib.rs

Author: lengyijun

clippy_lints/src/use_crate_prefix_for_self_imports.rs

@@ -4,8 +4,9 @@ use def_id::LOCAL_CRATE;
 use rustc_errors::Applicability;
 use rustc_hir::def::Res;
 use rustc_hir::*;
-use rustc_lint::{LateContext, LateLintPass};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::declare_lint_pass;
+use rustc_span::{FileName, RealFileName};
 
 declare_clippy_lint! {
     /// ### What it does
@@ -53,6 +54,17 @@ declare_lint_pass!(UseCratePrefixForSelfImports => [USE_CRATE_PREFIX_FOR_SELF_IM
 
 impl LateLintPass<'_> for UseCratePrefixForSelfImports {
     fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
+        let FileName::Real(RealFileName::LocalPath(p)) = cx.sess().source_map().span_to_filename(item.span) else {
+            return;
+        };
+        let Some(file_name) = p.file_name() else {
+            return;
+        };
+        // only check `main.rs` and `lib.rs`
+        if !(file_name == "main.rs" || file_name == "lib.rs") {
+            return;
+        }
+
         if let ItemKind::Use(use_path, _) = &item.kind {
             if let Some(segment) = use_path.segments.first()
                 && let Res::Def(_, def_id) = segment.res