fix: Fix comptime type formatting

compiler/noirc_frontend/src/hir/comptime/value.rs

@@ -101,8 +101,8 @@
         Value::Expr(ExprValue::Statement(statement))
     }
 
     pub(crate) fn lvalue(lvaue: LValue) -> Self {
         Value::Expr(ExprValue::LValue(lvaue))
     }
 
     pub(crate) fn pattern(pattern: Pattern) -> Self {
@@ -682,7 +682,7 @@
                 }
             }
             Value::Zeroed(typ) => write!(f, "(zeroed {typ})"),
-            Value::Type(typ) => write!(f, "{:?}", typ),
+            Value::Type(typ) => write!(f, "{}", typ),
             Value::Expr(ExprValue::Expression(expr)) => {
                 write!(f, "{}", remove_interned_in_expression_kind(self.interner, expr.clone()))
             }

test_programs/compile_success_empty/regression_6077/Nargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "regression_6077"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.30.0"
+
+[dependencies]

test_programs/compile_success_empty/regression_6077/Prover.toml

@@ -0,0 +1 @@
+a = 0

test_programs/compile_success_empty/regression_6077/src/main.nr

@@ -0,0 +1,28 @@
+struct WeirdStruct<T, U> {
+    a: T,
+    b: U,
+}
+
+#[mangle_fn]
+pub fn my_fn() -> [u8; 3] {
+    [0; 3]
+}
+
+comptime fn mangle_fn(f: FunctionDefinition) {
+    let return_type = f.return_type();
+
+    // This relies on how types are displayed
+    let generics = f"Field,{return_type}".quoted_contents();
+    let new_return_type = quote { WeirdStruct<$generics>}.as_type();
+
+    let new_body = quote {
+        {
+            WeirdStruct { a: 1, b: [0;3] }
+        }
+    }.as_expr().unwrap();
+
+    f.set_return_type(new_return_type);
+    f.set_body(new_body);
+}
+
+fn main() {}