From 4731d4b6d321e15f64e794ca4d95144bc29ca751 Mon Sep 17 00:00:00 2001
From: Martin Nordholts <enselic@gmail.com>
Date: Sat, 25 Jun 2022 21:36:52 +0200
Subject: [PATCH] rustc_passes: De-duplicate more code with `fn
 throw_attr_err()`

So we can re-use the code for other attributes later.
---
 compiler/rustc_passes/src/entry.rs | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/compiler/rustc_passes/src/entry.rs b/compiler/rustc_passes/src/entry.rs
index f9e67310452..1add91fc9c5 100644
--- a/compiler/rustc_passes/src/entry.rs
+++ b/compiler/rustc_passes/src/entry.rs
@@ -1,4 +1,4 @@
-use rustc_ast::entry::EntryPointType;
+use rustc_ast::{entry::EntryPointType, Attribute};
 use rustc_errors::struct_span_err;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
@@ -7,9 +7,8 @@
 use rustc_middle::ty::{DefIdTree, TyCtxt};
 use rustc_session::config::{CrateType, EntryFnType};
 use rustc_session::parse::feature_err;
-use rustc_session::Session;
 use rustc_span::symbol::sym;
-use rustc_span::{Span, DUMMY_SP};
+use rustc_span::{Span, Symbol, DUMMY_SP};
 
 struct EntryContext<'tcx> {
     tcx: TyCtxt<'tcx>,
@@ -72,9 +71,16 @@ fn entry_point_type(ctxt: &EntryContext<'_>, id: ItemId, at_root: bool) -> Entry
     }
 }
 
-fn throw_attr_err(sess: &Session, span: Span, attr: &str) {
-    sess.struct_span_err(span, &format!("`{}` attribute can only be used on functions", attr))
-        .emit();
+fn err_if_attr_found(ctxt: &EntryContext<'_>, attrs: &[Attribute], sym: Symbol) {
+    if let Some(attr) = ctxt.tcx.sess.find_by_name(attrs, sym) {
+        ctxt.tcx
+            .sess
+            .struct_span_err(
+                attr.span,
+                &format!("`{}` attribute can only be used on functions", sym.as_str()),
+            )
+            .emit();
+    }
 }
 
 fn find_item(id: ItemId, ctxt: &mut EntryContext<'_>) {
@@ -84,12 +90,8 @@ fn find_item(id: ItemId, ctxt: &mut EntryContext<'_>) {
         EntryPointType::None => (),
         _ if !matches!(ctxt.tcx.def_kind(id.def_id), DefKind::Fn) => {
             let attrs = ctxt.tcx.hir().attrs(id.hir_id());
-            if let Some(attr) = ctxt.tcx.sess.find_by_name(attrs, sym::start) {
-                throw_attr_err(&ctxt.tcx.sess, attr.span, "start");
-            }
-            if let Some(attr) = ctxt.tcx.sess.find_by_name(attrs, sym::rustc_main) {
-                throw_attr_err(&ctxt.tcx.sess, attr.span, "rustc_main");
-            }
+            err_if_attr_found(ctxt, attrs, sym::start);
+            err_if_attr_found(ctxt, attrs, sym::rustc_main);
         }
         EntryPointType::MainNamed => (),
         EntryPointType::OtherMain => {