Make mir dumps more readable

Author: oli-obk

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -1740,6 +1740,10 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
                     " as ",
                 )?;
             }
+            ty::Pat(base_ty, pat) => {
+                self.pretty_print_const_scalar_int(int, *base_ty, print_ty)?;
+                p!(write(" is {pat:?}"));
+            }
             // Nontrivial types with scalar bit representation
             _ => {
                 let print = |this: &mut Self| {

tests/mir-opt/pattern_types.main.PreCodegen.after.mir

@@ -3,9 +3,9 @@
 fn main() -> () {
     let mut _0: ();
     scope 1 {
-        debug x => const {transmute(0x00000002): (u32) is 1..=};
+        debug x => const 2_u32 is 1..=;
         scope 2 {
-            debug y => const {transmute(0x00000000): (u32) is 1..=};
+            debug y => const 0_u32 is 1..=;
         }
     }
 

tests/mir-opt/pattern_types.rs

@@ -5,8 +5,8 @@ use std::pat::pattern_type;
 
 // EMIT_MIR pattern_types.main.PreCodegen.after.mir
 fn main() {
-    // CHECK: debug x => const {transmute(0x00000002): (u32) is 1..=}
+    // CHECK: debug x => const 2_u32 is 1..=
     let x: pattern_type!(u32 is 1..) = unsafe { std::mem::transmute(2) };
-    // CHECK: debug y => const {transmute(0x00000000): (u32) is 1..=}
+    // CHECK: debug y => const 0_u32 is 1..=
     let y: pattern_type!(u32 is 1..) = unsafe { std::mem::transmute(0) };
 }