From 772292fa5180516f34fdcbe704c16203f7f38202 Mon Sep 17 00:00:00 2001
From: Aaron Hill <aa1ronham@gmail.com>
Date: Fri, 27 Nov 2020 09:36:59 -0500
Subject: [PATCH] Don't lint on redundant semicolons after item statements

This preserves the current lint behavior for now.

Linting after item statements currently prevents the compiler from bootstrapping.
Fixing this is blocked on fixing this upstream in Cargo, and bumping the Cargo
submodule.
---
 .../rustc_lint/src/redundant_semicolon.rs     | 21 ++++++++++++++++---
 .../redundant-semicolon/item-stmt-semi.rs     | 10 +++++++++
 2 files changed, 28 insertions(+), 3 deletions(-)
 create mode 100644 src/test/ui/lint/redundant-semicolon/item-stmt-semi.rs

diff --git a/compiler/rustc_lint/src/redundant_semicolon.rs b/compiler/rustc_lint/src/redundant_semicolon.rs
index 84cc7b68d4ca9..428198cae8917 100644
--- a/compiler/rustc_lint/src/redundant_semicolon.rs
+++ b/compiler/rustc_lint/src/redundant_semicolon.rs
@@ -28,25 +28,40 @@ declare_lint_pass!(RedundantSemicolons => [REDUNDANT_SEMICOLONS]);
 
 impl EarlyLintPass for RedundantSemicolons {
     fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
+        let mut after_item_stmt = false;
         let mut seq = None;
         for stmt in block.stmts.iter() {
             match (&stmt.kind, &mut seq) {
                 (StmtKind::Empty, None) => seq = Some((stmt.span, false)),
                 (StmtKind::Empty, Some(seq)) => *seq = (seq.0.to(stmt.span), true),
-                (_, seq) => maybe_lint_redundant_semis(cx, seq),
+                (_, seq) => {
+                    maybe_lint_redundant_semis(cx, seq, after_item_stmt);
+                    after_item_stmt = matches!(stmt.kind, StmtKind::Item(_));
+                }
             }
         }
-        maybe_lint_redundant_semis(cx, &mut seq);
+        maybe_lint_redundant_semis(cx, &mut seq, after_item_stmt);
     }
 }
 
-fn maybe_lint_redundant_semis(cx: &EarlyContext<'_>, seq: &mut Option<(Span, bool)>) {
+fn maybe_lint_redundant_semis(
+    cx: &EarlyContext<'_>,
+    seq: &mut Option<(Span, bool)>,
+    after_item_stmt: bool,
+) {
     if let Some((span, multiple)) = seq.take() {
         // FIXME: Find a better way of ignoring the trailing
         // semicolon from macro expansion
         if span == rustc_span::DUMMY_SP {
             return;
         }
+
+        // FIXME: Lint on semicolons after item statements
+        // once doing so doesn't break bootstrapping
+        if after_item_stmt {
+            return;
+        }
+
         cx.struct_span_lint(REDUNDANT_SEMICOLONS, span, |lint| {
             let (msg, rem) = if multiple {
                 ("unnecessary trailing semicolons", "remove these semicolons")
diff --git a/src/test/ui/lint/redundant-semicolon/item-stmt-semi.rs b/src/test/ui/lint/redundant-semicolon/item-stmt-semi.rs
new file mode 100644
index 0000000000000..4592bc31a3976
--- /dev/null
+++ b/src/test/ui/lint/redundant-semicolon/item-stmt-semi.rs
@@ -0,0 +1,10 @@
+// check-pass
+// This test should stop compiling
+// we decide to enable this lint for item statements.
+
+#![deny(redundant_semicolons)]
+
+fn main() {
+    fn inner() {};
+    struct Bar {};
+}