[meta] Add some Debug derives

cranelift/codegen/meta/src/cdsl/ast.rs

@@ -8,6 +8,7 @@ use cranelift_entity::{entity_impl, PrimaryMap};
 
 use std::fmt;
 
+#[derive(Debug)]
 pub enum Expr {
     Var(VarIndex),
     Literal(Literal),
@@ -363,6 +364,7 @@ impl VarPool {
 ///
 /// An `Apply` AST expression is created by using function call syntax on instructions. This
 /// applies to both bound and unbound polymorphic instructions.
+#[derive(Debug)]
 pub struct Apply {
     pub inst: Instruction,
     pub args: Vec<Expr>,

cranelift/codegen/meta/src/cdsl/instructions.rs

@@ -79,12 +79,14 @@ impl InstructionGroup {
     }
 }
 
+#[derive(Debug)]
 pub struct PolymorphicInfo {
     pub use_typevar_operand: bool,
     pub ctrl_typevar: TypeVar,
     pub other_typevars: Vec<TypeVar>,
 }
 
+#[derive(Debug)]
 pub struct InstructionContent {
     /// Instruction mnemonic, also becomes opcode name.
     pub name: String,
@@ -139,7 +141,7 @@ pub struct InstructionContent {
     pub writes_cpu_flags: bool,
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct Instruction {
     content: Rc<InstructionContent>,
 }

cranelift/codegen/meta/src/cdsl/type_inference.rs

@@ -4,7 +4,7 @@ use crate::cdsl::typevar::{DerivedFunc, TypeSet, TypeVar};
 use std::collections::{HashMap, HashSet};
 use std::iter::FromIterator;
 
-#[derive(Hash, PartialEq, Eq)]
+#[derive(Debug, Hash, PartialEq, Eq)]
 pub enum Constraint {
     /// Constraint specifying that a type var tv1 must be wider than or equal to type var tv2 at
     /// runtime. This requires that: