Add helper for getting an int out of a Scalar

Author: oli-obk

compiler/rustc_middle/src/mir/interpret/value.rs

@@ -357,6 +357,14 @@ impl<'tcx, Tag> Scalar<Tag> {
         self.to_bits(target_size).expect("expected Raw bits but got a Pointer")
     }
 
+    #[inline]
+    pub fn assert_int(self) -> ScalarInt {
+        match self {
+            Scalar::Ptr(_) => bug!("expected an int but got an abstract pointer"),
+            Scalar::Int(int) => int,
+        }
+    }
+
     #[inline]
     pub fn assert_ptr(self) -> Pointer<Tag> {
         match self {

compiler/rustc_mir/src/interpret/operand.rs

@@ -211,10 +211,7 @@ impl<'tcx, Tag: Copy> ImmTy<'tcx, Tag> {
     #[inline]
     pub fn to_const_int(self) -> ConstInt {
         assert!(self.layout.ty.is_integral());
-        let int = match self.to_scalar().expect("to_const_int doesn't work on scalar pairs") {
-            Scalar::Int(int) => int,
-            Scalar::Ptr(_) => bug!("to_const_int doesn't work on pointers"),
-        };
+        let int = self.to_scalar().expect("to_const_int doesn't work on scalar pairs").assert_int();
         ConstInt::new(int, self.layout.ty.is_signed(), self.layout.ty.is_ptr_sized_integral())
     }
 }