From df6e6a6d08f1ccd04e852896553e3fd7927dcdd6 Mon Sep 17 00:00:00 2001
From: mojave2 <chenchen145@huawei.com>
Date: Wed, 6 Sep 2023 10:51:28 +0800
Subject: [PATCH 1/2] fix #115348

---
 compiler/rustc_mir_transform/src/check_unsafety.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler/rustc_mir_transform/src/check_unsafety.rs b/compiler/rustc_mir_transform/src/check_unsafety.rs
index 0fce9cb19a8..d5af321d726 100644
--- a/compiler/rustc_mir_transform/src/check_unsafety.rs
+++ b/compiler/rustc_mir_transform/src/check_unsafety.rs
@@ -483,7 +483,7 @@ fn unsafety_check_result(tcx: TyCtxt<'_>, def: LocalDefId) -> &UnsafetyCheckResu
     // `mir_built` force this.
     let body = &tcx.mir_built(def).borrow();
 
-    if body.is_custom_mir() {
+    if body.is_custom_mir() || body.tainted_by_errors.is_some() {
         return tcx.arena.alloc(UnsafetyCheckResult {
             violations: Vec::new(),
             used_unsafe_blocks: Default::default(),

From cfa211956309a444371442c5956d59a12260dcee Mon Sep 17 00:00:00 2001
From: mojave2 <chenchen145@huawei.com>
Date: Wed, 6 Sep 2023 17:46:39 +0800
Subject: [PATCH 2/2] add a regression test

---
 ...-positive-warning-of-unnecessary-unsafe.rs | 16 ++++++++++++++
 ...itive-warning-of-unnecessary-unsafe.stderr | 21 +++++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 tests/ui/unsafe/issue-115348-false-positive-warning-of-unnecessary-unsafe.rs
 create mode 100644 tests/ui/unsafe/issue-115348-false-positive-warning-of-unnecessary-unsafe.stderr

diff --git a/tests/ui/unsafe/issue-115348-false-positive-warning-of-unnecessary-unsafe.rs b/tests/ui/unsafe/issue-115348-false-positive-warning-of-unnecessary-unsafe.rs
new file mode 100644
index 00000000000..68559338d49
--- /dev/null
+++ b/tests/ui/unsafe/issue-115348-false-positive-warning-of-unnecessary-unsafe.rs
@@ -0,0 +1,16 @@
+// Regression test for #115348.
+
+unsafe fn uwu() {}
+
+// Tests that the false-positive warning "unnecessary `unsafe` block"
+// should not be reported, when the error "non-exhaustive patterns"
+// appears.
+
+fn foo(x: Option<u32>) {
+    match x {
+        //~^ ERROR non-exhaustive patterns: `None` not covered
+        Some(_) => unsafe { uwu() },
+    }
+}
+
+fn main() {}
diff --git a/tests/ui/unsafe/issue-115348-false-positive-warning-of-unnecessary-unsafe.stderr b/tests/ui/unsafe/issue-115348-false-positive-warning-of-unnecessary-unsafe.stderr
new file mode 100644
index 00000000000..7384899b978
--- /dev/null
+++ b/tests/ui/unsafe/issue-115348-false-positive-warning-of-unnecessary-unsafe.stderr
@@ -0,0 +1,21 @@
+error[E0004]: non-exhaustive patterns: `None` not covered
+  --> $DIR/issue-115348-false-positive-warning-of-unnecessary-unsafe.rs:10:11
+   |
+LL |     match x {
+   |           ^ pattern `None` not covered
+   |
+note: `Option<u32>` defined here
+  --> $SRC_DIR/core/src/option.rs:LL:COL
+  ::: $SRC_DIR/core/src/option.rs:LL:COL
+   |
+   = note: not covered
+   = note: the matched value is of type `Option<u32>`
+help: ensure that all possible cases are being handled by adding a match arm with a wildcard pattern or an explicit pattern as shown
+   |
+LL ~         Some(_) => unsafe { uwu() },
+LL ~         None => todo!(),
+   |
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0004`.