Add a method to pretty print decl ids to the DeclEngine.

sway-core/src/decl_engine/engine.rs

@@ -1,12 +1,13 @@
 use std::{
     collections::{HashMap, HashSet, VecDeque},
+    fmt::Write,
     sync::RwLock,
 };
 
 use sway_types::{Named, Spanned};
 
 use crate::{
-    concurrent_slab::ConcurrentSlab,
+    concurrent_slab::{ConcurrentSlab, ListDisplay},
     decl_engine::*,
     engine_threading::*,
     language::ty::{
@@ -321,4 +322,19 @@ impl DeclEngine {
     {
         self.get(index)
     }
+
+    /// Pretty print method for printing the [DeclEngine]. This method is
+    /// manually implemented to avoid implementation overhead regarding using
+    /// [DisplayWithEngines].
+    pub fn pretty_print(&self, engines: &Engines) -> String {
+        let mut builder = String::new();
+        self.function_slab.with_slice(|elems| {
+            let list = elems
+                .iter()
+                .map(|type_info| format!("{:?}", engines.help_out(type_info)));
+            let list = ListDisplay { list };
+            write!(builder, "DeclEngine {{\n{list}\n}}").unwrap();
+        });
+        builder
+    }
 }

sway-core/src/language/ty/declaration/function.rs

@@ -1,5 +1,6 @@
 use std::{
     collections::HashSet,
+    fmt,
     hash::{Hash, Hasher},
 };
 
@@ -41,6 +42,12 @@ pub struct TyFunctionDecl {
     pub is_trait_method_dummy: bool,
 }
 
+impl DebugWithEngines for TyFunctionDecl {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>, _engines: &Engines) -> fmt::Result {
+        write!(f, "{:?}", self.name,)
+    }
+}
+
 impl Named for TyFunctionDecl {
     fn name(&self) -> &Ident {
         &self.name