polish the rendering a bit, add a macro

teleprof-macros/src/lib.rs

@@ -66,7 +66,22 @@ pub fn instrument_calls(_args: TokenStream, input: TokenStream) -> TokenStream {
     let mut visitor = CallInstrumenter;
     visitor.visit_block_mut(&mut input_fn.block);
 
-    TokenStream::from(quote! { #input_fn })
+    // Add an outer span for the function itself
+    let fn_name = input_fn.sig.ident.to_string();
+    let fn_vis = &input_fn.vis;
+    let fn_sig = &input_fn.sig;
+    let fn_block = &input_fn.block;
+    let fn_attrs = &input_fn.attrs;
+
+    let instrumented = quote! {
+        #(#fn_attrs)*
+        #fn_vis #fn_sig {
+            let _guard = ::teleprof::SpanGuard::new(#fn_name);
+            #fn_block
+        }
+    };
+
+    TokenStream::from(instrumented)
 }
 
 struct CallInstrumenter;