Rollup merge of #136176 - oli-obk:pattern-type-mir-opts, r=compiler-errors

Render pattern types nicely in mir dumps

avoid falling through to the fallback rendering that just does a hex dump

r? ``@scottmcm``

best reviewed commit by commit

Author: fmease

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

@@ -0,0 +1,15 @@
+// MIR for `main` after PreCodegen
+
+fn main() -> () {
+    let mut _0: ();
+    scope 1 {
+        debug x => const 2_u32 is 1..=;
+        scope 2 {
+            debug y => const 0_u32 is 1..=;
+        }
+    }
+
+    bb0: {
+        return;
+    }
+}

tests/mir-opt/pattern_types.rs

@@ -0,0 +1,12 @@
+#![feature(pattern_types)]
+#![feature(pattern_type_macro)]
+
+use std::pat::pattern_type;
+
+// EMIT_MIR pattern_types.main.PreCodegen.after.mir
+fn main() {
+    // CHECK: debug x => const 2_u32 is 1..=
+    let x: pattern_type!(u32 is 1..) = unsafe { std::mem::transmute(2) };
+    // CHECK: debug y => const 0_u32 is 1..=
+    let y: pattern_type!(u32 is 1..) = unsafe { std::mem::transmute(0) };
+}