Rollup merge of rust-lang#75580 - JulianKnodt:or_pattern, r=wesleywiser

Add test for checking duplicated branch or-patterns

This adds a regression test for checking `or-patterns` in MIR as shown in rust-lang#75439.
This doesn't introduce a fix as I'm not sure where it would go(I suspect maybe here: src/librustc_mir_build/build/matches/mod.rs), and I'm not particularly able to fix it.

cc: @lzutao

src/test/mir-opt/issues/issue-75439.rs

@@ -0,0 +1,21 @@
+// EMIT_MIR issue_75439.foo.MatchBranchSimplification.diff
+
+#![feature(const_fn_transmute)]
+#![feature(or_patterns)]
+
+use std::mem::transmute;
+
+pub fn foo(bytes: [u8; 16]) -> Option<[u8; 4]> {
+    // big endian `u32`s
+    let dwords: [u32; 4] = unsafe { transmute(bytes) };
+    const FF: u32 = 0x0000_ffff_u32.to_be();
+    if let [0, 0, 0 | FF, ip] = dwords {
+        Some(unsafe { transmute(ip) })
+    } else {
+        None
+    }
+}
+
+fn main() {
+  let _ = foo([0; 16]);
+}

src/test/mir-opt/issues/issue_75439.foo.MatchBranchSimplification.diff

@@ -0,0 +1,87 @@
+- // MIR for `foo` before MatchBranchSimplification
++ // MIR for `foo` after MatchBranchSimplification
+
+  fn foo(_1: [u8; 16]) -> std::option::Option<[u8; 4]> {
+      debug bytes => _1;                   // in scope 0 at $DIR/issue-75439.rs:8:12: 8:17
+      let mut _0: std::option::Option<[u8; 4]>; // return place in scope 0 at $DIR/issue-75439.rs:8:32: 8:47
+      let _2: [u32; 4];                    // in scope 0 at $DIR/issue-75439.rs:10:9: 10:15
+      let mut _3: [u8; 16];                // in scope 0 at $DIR/issue-75439.rs:10:47: 10:52
+      let mut _5: [u8; 4];                 // in scope 0 at $DIR/issue-75439.rs:13:14: 13:38
+      let mut _6: u32;                     // in scope 0 at $DIR/issue-75439.rs:13:33: 13:35
+      scope 1 {
+          debug dwords => _2;              // in scope 1 at $DIR/issue-75439.rs:10:9: 10:15
+          let _4: u32;                     // in scope 1 at $DIR/issue-75439.rs:12:27: 12:29
+          scope 3 {
+              debug ip => _4;              // in scope 3 at $DIR/issue-75439.rs:12:27: 12:29
+              scope 4 {
+              }
+          }
+      }
+      scope 2 {
+      }
+
+      bb0: {
+          StorageLive(_2);                 // scope 0 at $DIR/issue-75439.rs:10:9: 10:15
+          StorageLive(_3);                 // scope 2 at $DIR/issue-75439.rs:10:47: 10:52
+          _3 = _1;                         // scope 2 at $DIR/issue-75439.rs:10:47: 10:52
+          _2 = std::intrinsics::transmute::<[u8; 16], [u32; 4]>(move _3) -> bb1; // scope 2 at $DIR/issue-75439.rs:10:37: 10:53
+                                           // mir::Constant
+                                           // + span: $DIR/issue-75439.rs:10:37: 10:46
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn([u8; 16]) -> [u32; 4] {std::intrinsics::transmute::<[u8; 16], [u32; 4]>}, val: Value(Scalar(<ZST>)) }
+      }
+
+      bb1: {
+          StorageDead(_3);                 // scope 2 at $DIR/issue-75439.rs:10:52: 10:53
+          switchInt(_2[0 of 4]) -> [0_u32: bb2, otherwise: bb4]; // scope 1 at $DIR/issue-75439.rs:12:13: 12:14
+      }
+
+      bb2: {
+          switchInt(_2[1 of 4]) -> [0_u32: bb3, otherwise: bb4]; // scope 1 at $DIR/issue-75439.rs:12:16: 12:17
+      }
+
+      bb3: {
+          switchInt(_2[2 of 4]) -> [0_u32: bb6, 4294901760_u32: bb7, otherwise: bb4]; // scope 1 at $DIR/issue-75439.rs:12:19: 12:20
+      }
+
+      bb4: {
+          discriminant(_0) = 0;            // scope 1 at $DIR/issue-75439.rs:15:9: 15:13
+          goto -> bb9;                     // scope 1 at $DIR/issue-75439.rs:12:5: 16:6
+      }
+
+      bb5: {
+          StorageLive(_5);                 // scope 3 at $DIR/issue-75439.rs:13:14: 13:38
+          StorageLive(_6);                 // scope 4 at $DIR/issue-75439.rs:13:33: 13:35
+          _6 = _4;                         // scope 4 at $DIR/issue-75439.rs:13:33: 13:35
+          _5 = std::intrinsics::transmute::<u32, [u8; 4]>(move _6) -> bb8; // scope 4 at $DIR/issue-75439.rs:13:23: 13:36
+                                           // mir::Constant
+                                           // + span: $DIR/issue-75439.rs:13:23: 13:32
+                                           // + literal: Const { ty: unsafe extern "rust-intrinsic" fn(u32) -> [u8; 4] {std::intrinsics::transmute::<u32, [u8; 4]>}, val: Value(Scalar(<ZST>)) }
+      }
+
+      bb6: {
+          StorageLive(_4);                 // scope 1 at $DIR/issue-75439.rs:12:27: 12:29
+          _4 = _2[3 of 4];                 // scope 1 at $DIR/issue-75439.rs:12:27: 12:29
+          goto -> bb5;                     // scope 1 at $DIR/issue-75439.rs:12:5: 16:6
+      }
+
+      bb7: {
+          StorageLive(_4);                 // scope 1 at $DIR/issue-75439.rs:12:27: 12:29
+          _4 = _2[3 of 4];                 // scope 1 at $DIR/issue-75439.rs:12:27: 12:29
+          goto -> bb5;                     // scope 1 at $DIR/issue-75439.rs:12:5: 16:6
+      }
+
+      bb8: {
+          StorageDead(_6);                 // scope 4 at $DIR/issue-75439.rs:13:35: 13:36
+          ((_0 as Some).0: [u8; 4]) = move _5; // scope 3 at $DIR/issue-75439.rs:13:9: 13:39
+          discriminant(_0) = 1;            // scope 3 at $DIR/issue-75439.rs:13:9: 13:39
+          StorageDead(_5);                 // scope 3 at $DIR/issue-75439.rs:13:38: 13:39
+          StorageDead(_4);                 // scope 1 at $DIR/issue-75439.rs:14:5: 14:6
+          goto -> bb9;                     // scope 1 at $DIR/issue-75439.rs:12:5: 16:6
+      }
+
+      bb9: {
+          StorageDead(_2);                 // scope 0 at $DIR/issue-75439.rs:17:1: 17:2
+          return;                          // scope 0 at $DIR/issue-75439.rs:17:2: 17:2
+      }
+  }
+