use a feature flag rather than conditional compilation

Cargo.toml

@@ -12,6 +12,7 @@ license = "MIT"
 
 [features]
 default = []
+slow_function_warning = []
 
 [lib]
 proc-macro = true

README.md

@@ -30,47 +30,17 @@ fn example_function() {
 }
 ```
 
-## Debug Only Example
+The warning is not on by default and is only recommended for debugging purposes. To enable it use the `slow_function_warning` feature.
 
-```rust
-#[cfg_attr(debug_assertions, slow_function_warning(1000ms))]
-fn example_function() {
-    // Function implementation
-}
-```
-
-Or using the convenience proc macro:
-
-```rust
-#[debug_slow_function_warning(1000ms)]
-fn example_function() {
-    // Function implementation
-}
-```
-
-## Release Only Example
-
-```rust
-#[cfg_attr(not(debug_assertions), slow_function_warning(1000ms))]
-fn example_function() {
-    // Function implementation
-}
-```
-
-Or using the convenience proc macro:
-
-```rust
-#[release_slow_function_warning(1000ms)]
-fn example_function() {
-    // Function implementation
-}
-```
+~~~bash
+cargo run --features slow_function_warning
+~~~
 
 ## Custom Message Example
 
 ```rust
 // Warn if the function takes longer than a second with a custom message
-#[debug_slow_function_warning(1s, println!("Function {function} took too long!"))]
+#[slow_function_warning(1s, println!("Function {function} took too long!"))]
 fn example_function() {
     // Function implementation
 }

src/lib.rs

@@ -34,23 +34,10 @@ fn parse_time(expr: &Expr) -> Result<Duration> {
 }
 
 #[proc_macro_attribute]
-pub fn debug_slow_function_warning(args: TokenStream, input: TokenStream) -> TokenStream {
-    if !cfg!(debug_assertions) {
-        return input;
-    }
-    slow_function_warning(args, input)
-}
-
-#[proc_macro_attribute]
-pub fn release_slow_function_warning(args: TokenStream, input: TokenStream) -> TokenStream {
-    if cfg!(debug_assertions) {
+pub fn slow_function_warning(args: TokenStream, input: TokenStream) -> TokenStream {
+    if !cfg!(feature = "slow_function_warning") {
         return input;
     }
-    slow_function_warning(args, input)
-}
-
-#[proc_macro_attribute]
-pub fn slow_function_warning(args: TokenStream, input: TokenStream) -> TokenStream {
     let args: Punctuated<Expr, Token![,]> = if !args.is_empty() {
         parse_macro_input!(args with Punctuated::<Expr, Token![,]>::parse_separated_nonempty)
             .into_iter()