Example of an error when lifetime not specified

.gitignore

@@ -0,0 +1 @@
+/target

Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "lifetimes"
+version = "0.1.0"

Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "lifetimes"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/main.rs

@@ -0,0 +1,15 @@
+fn main() {
+    let s1 = "Hello worlc";
+    let s2 = "Hello";
+
+    let result: &str = longest(s1, s2);
+    println!("The longest string is {result}");
+}
+
+fn longest(a: &str, b: &str) -> &str {
+    if a.len() > b.len() {
+        a
+    } else {
+        b
+    }
+}