From c33cf02c9a6fffc6149fd7b59c63ad0d15d61432 Mon Sep 17 00:00:00 2001
From: HampusM <hampus@hampusmat.com>
Date: Wed, 3 Aug 2022 11:50:59 +0200
Subject: refactor: add Cargo feature for preventing circular dependencies

---
 Cargo.toml                    |  2 ++
 README.md                     |  2 +-
 macros/Cargo.toml             |  1 +
 macros/src/injectable_impl.rs | 40 ++++++++++++++++++++++++----------------
 4 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index ac1cee9..3fd751a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,7 +12,9 @@ edition = "2021"
 all-features = true
 
 [features]
+default = ["prevent-circular"]
 factory = ["syrette_macros/factory"]
+prevent-circular = ["syrette_macros/prevent-circular"]
 
 [[example]]
 name = "factory"
diff --git a/README.md b/README.md
index c244345..50dc5ac 100644
--- a/README.md
+++ b/README.md
@@ -19,10 +19,10 @@ From the [syrette Wikipedia article](https://en.wikipedia.org/wiki/Syrette).
 - Enforces the use of interface traits
 - Supports generic implementations & generic interface traits
 - Binding singletons
-- Detection and prevention of circular dependencies
 
 ## Optional features
 - `factory`. Binding factories (Rust nightly required)
+- `prevent-circular`. Detection and prevention of circular dependencies. (Enabled by default)
 
 To use these features, you must [enable it in Cargo](https://doc.rust-lang.org/cargo/reference/features.html#dependency-features).
 
diff --git a/macros/Cargo.toml b/macros/Cargo.toml
index 36cc8eb..73f583d 100644
--- a/macros/Cargo.toml
+++ b/macros/Cargo.toml
@@ -16,6 +16,7 @@ all-features = true
 
 [features]
 factory = []
+prevent-circular = []
 
 [dependencies]
 syn = { version = "1.0.96", features = ["full"] }
diff --git a/macros/src/injectable_impl.rs b/macros/src/injectable_impl.rs
index 3bd7113..29e0094 100644
--- a/macros/src/injectable_impl.rs
+++ b/macros/src/injectable_impl.rs
@@ -66,6 +66,29 @@ impl InjectableImpl
             }
         };
 
+        let maybe_prevent_circular_deps = if cfg!(feature = "prevent-circular") {
+            quote! {
+                if dependency_history.contains(&self_type_name) {
+                    dependency_history.push(self_type_name);
+
+                    return Err(
+                        report!(ResolveError)
+                            .attach_printable(format!(
+                                "Detected circular dependencies. {}",
+                                syrette::dependency_trace::create_dependency_trace(
+                                    dependency_history.as_slice(),
+                                    self_type_name
+                                )
+                            ))
+                    );
+                }
+
+                dependency_history.push(self_type_name);
+            }
+        } else {
+            quote! {}
+        };
+
         quote! {
             #original_impl
 
@@ -83,22 +106,7 @@ impl InjectableImpl
 
                     let self_type_name = std::any::type_name::<#self_type>();
 
-                    if dependency_history.contains(&self_type_name) {
-                        dependency_history.push(self_type_name);
-
-                        return Err(
-                            report!(ResolveError)
-                                .attach_printable(format!(
-                                    "Detected circular dependencies. {}",
-                                    syrette::dependency_trace::create_dependency_trace(
-                                        dependency_history.as_slice(),
-                                        self_type_name
-                                    )
-                                ))
-                        );
-                    }
-
-                    dependency_history.push(self_type_name);
+                    #maybe_prevent_circular_deps
 
                     return Ok(syrette::ptr::TransientPtr::new(Self::new(
                         #(#get_dependencies
-- 
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