From: Santiago Pastorino <spastorino@gmail.com>
Date: Thu, 18 Mar 2021 20:35:46 +0000 (-0300)
Subject: Mark early otherwise optimization unsound
X-Git-Url: https://git.lizzy.rs/?a=commitdiff_plain;h=778e1978d5ad67b1e4f69622b86237b1f4732f0f;hp=1705a7d64b833d1c4b69958b0627bd054e6d764b;p=rust.git

Mark early otherwise optimization unsound
---

diff --git a/compiler/rustc_mir/src/transform/early_otherwise_branch.rs b/compiler/rustc_mir/src/transform/early_otherwise_branch.rs
index e64a539c7f8..f7ea9faec47 100644
--- a/compiler/rustc_mir/src/transform/early_otherwise_branch.rs
+++ b/compiler/rustc_mir/src/transform/early_otherwise_branch.rs
@@ -26,6 +26,11 @@
 
 impl<'tcx> MirPass<'tcx> for EarlyOtherwiseBranch {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
+        //  FIXME(#78496)
+        if !tcx.sess.opts.debugging_opts.unsound_mir_opts {
+            return;
+        }
+
         if tcx.sess.mir_opt_level() < 3 {
             return;
         }
diff --git a/src/test/mir-opt/early_otherwise_branch.rs b/src/test/mir-opt/early_otherwise_branch.rs
index 548213ab83c..b2caf7d7b8f 100644
--- a/src/test/mir-opt/early_otherwise_branch.rs
+++ b/src/test/mir-opt/early_otherwise_branch.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=4
+// compile-flags: -Z mir-opt-level=4 -Z unsound-mir-opts
 // EMIT_MIR early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff
 fn opt1(x: Option<u32>, y: Option<u32>) -> u32 {
     match (x, y) {
diff --git a/src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs b/src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs
index aa304f747f7..8527c01d756 100644
--- a/src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs
+++ b/src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=4
+// compile-flags: -Z mir-opt-level=4 -Z unsound-mir-opts
 
 // EMIT_MIR early_otherwise_branch_3_element_tuple.opt1.EarlyOtherwiseBranch.diff
 fn opt1(x: Option<u32>, y: Option<u32>, z: Option<u32>) -> u32 {