Fix unsafetyck disabling for custom MIR

Author: JakobDegen

compiler/rustc_middle/src/mir/mod.rs

@@ -533,6 +533,11 @@ impl<'tcx> Body<'tcx> {
         };
         injection_phase > self.phase
     }
+
+    #[inline]
+    pub fn is_custom_mir(&self) -> bool {
+        self.injection_phase.is_some()
+    }
 }
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]

compiler/rustc_mir_transform/src/check_unsafety.rs

@@ -500,7 +500,7 @@ fn unsafety_check_result<'tcx>(
     // `mir_built` force this.
     let body = &tcx.mir_built(def).borrow();
 
-    if body.should_skip() {
+    if body.is_custom_mir() {
         return tcx.arena.alloc(UnsafetyCheckResult {
             violations: Vec::new(),
             used_unsafe_blocks: FxHashSet::default(),

src/test/mir-opt/building/custom/references.raw_pointer.built.after.mir

@@ -0,0 +1,10 @@
+// MIR for `raw_pointer` after built
+
+fn raw_pointer(_1: *const i32) -> *const i32 {
+    let mut _0: *const i32;              // return place in scope 0 at $DIR/references.rs:+0:38: +0:48
+
+    bb0: {
+        _0 = &raw const (*_1);           // scope 0 at $DIR/references.rs:+4:9: +4:27
+        return;                          // scope 0 at $DIR/references.rs:+5:9: +5:17
+    }
+}

src/test/mir-opt/building/custom/references.rs

@@ -36,8 +36,22 @@ pub fn immut_ref(x: &i32) -> &i32 {
     )
 }
 
+// EMIT_MIR references.raw_pointer.built.after.mir
+#[custom_mir(dialect = "built")]
+pub fn raw_pointer(x: *const i32) -> *const i32 {
+    // Regression test for a bug in which unsafetyck was not correctly turned off for
+    // `dialect = "built"`
+    mir!({
+        RET = addr_of!(*x);
+        Return()
+    })
+}
+
 fn main() {
     let mut x = 5;
     assert_eq!(*mut_ref(&mut x), 5);
     assert_eq!(*immut_ref(&x), 5);
+    unsafe {
+        assert_eq!(*raw_pointer(addr_of!(x)), 5);
+    }
 }