From b76faff1b281fdf199e5abe8ff0c8d6d2e2e2a85 Mon Sep 17 00:00:00 2001
From: Scott McMurray <scottmcm@users.noreply.github.com>
Date: Fri, 29 Mar 2024 00:37:31 -0700
Subject: [PATCH] Add a MIR pre-codegen test for Vec::deref

---
 tests/mir-opt/pre-codegen/vec_deref.rs             | 13 +++++++++++++
 ...deref_to_slice.PreCodegen.after.panic-abort.mir | 14 ++++++++++++++
 ...eref_to_slice.PreCodegen.after.panic-unwind.mir | 14 ++++++++++++++
 3 files changed, 41 insertions(+)
 create mode 100644 tests/mir-opt/pre-codegen/vec_deref.rs
 create mode 100644 tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir
 create mode 100644 tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir

diff --git a/tests/mir-opt/pre-codegen/vec_deref.rs b/tests/mir-opt/pre-codegen/vec_deref.rs
new file mode 100644
index 000000000000..3476e1760c0a
--- /dev/null
+++ b/tests/mir-opt/pre-codegen/vec_deref.rs
@@ -0,0 +1,13 @@
+// skip-filecheck
+//@ compile-flags: -O -Zmir-opt-level=2 -Cdebuginfo=2
+// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
+
+#![crate_type = "lib"]
+
+// Added after it stopped inlining in a nightly; see
+// <https://github.com/rust-lang/rust/issues/123174>
+
+// EMIT_MIR vec_deref.vec_deref_to_slice.PreCodegen.after.mir
+pub fn vec_deref_to_slice(v: &Vec<u8>) -> &[u8] {
+    v
+}
diff --git a/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir
new file mode 100644
index 000000000000..df8d5c3836f1
--- /dev/null
+++ b/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-abort.mir
@@ -0,0 +1,14 @@
+// MIR for `vec_deref_to_slice` after PreCodegen
+
+fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
+    debug v => _1;
+    let mut _0: &[u8];
+
+    bb0: {
+        _0 = <Vec<u8> as Deref>::deref(move _1) -> [return: bb1, unwind unreachable];
+    }
+
+    bb1: {
+        return;
+    }
+}
diff --git a/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir
new file mode 100644
index 000000000000..d26afef4653e
--- /dev/null
+++ b/tests/mir-opt/pre-codegen/vec_deref.vec_deref_to_slice.PreCodegen.after.panic-unwind.mir
@@ -0,0 +1,14 @@
+// MIR for `vec_deref_to_slice` after PreCodegen
+
+fn vec_deref_to_slice(_1: &Vec<u8>) -> &[u8] {
+    debug v => _1;
+    let mut _0: &[u8];
+
+    bb0: {
+        _0 = <Vec<u8> as Deref>::deref(move _1) -> [return: bb1, unwind continue];
+    }
+
+    bb1: {
+        return;
+    }
+}