Do not require 'fn main()' in script files

Surround the script file with 'fn main() { .. }' if no line starts
with 'fn main()'.

src/manifest.rs

@@ -50,19 +50,24 @@ pub fn split_input(
             let (manifest, source) =
                 find_embedded_manifest(content).unwrap_or((Manifest::Toml(""), content));
 
+            let source = if source.lines().any(|line| line.starts_with("fn main()")) {
+                source.to_string()
+            } else {
+                format!("fn main() {{\n{}\n}}", source)
+            };
             (manifest, source, templates::get_template("file")?, false)
         }
         Input::Expr(content, template) => {
             template_buf = templates::get_template(template.unwrap_or("expr"))?;
             let (manifest, template_src) = find_embedded_manifest(&template_buf)
                 .unwrap_or((Manifest::Toml(""), &template_buf));
-            (manifest, content, template_src.into(), true)
+            (manifest, content.to_string(), template_src.into(), true)
         }
         Input::Loop(content, count) => {
             let templ = if count { "loop-count" } else { "loop" };
             (
                 Manifest::Toml(""),
-                content,
+                content.to_string(),
                 templates::get_template(templ)?,
                 true,
             )
@@ -71,6 +76,7 @@ pub fn split_input(
 
     let mut prelude_str;
     let mut subs = HashMap::with_capacity(2);
+
     subs.insert(consts::SCRIPT_BODY_SUB, &source[..]);
 
     if sub_prelude {

tests/data/script-full-block.rs

@@ -4,7 +4,6 @@
 //! [dependencies]
 //! boolinator = "=0.1.0"
 //! ```
-extern crate boolinator;
 use boolinator::Boolinator;
 fn main() {
     println!("--output--");

tests/data/script-full-line-without-main.rs

@@ -0,0 +1,13 @@
+#!/usr/bin/env rust-script
+/*!
+This is merged into a default manifest in order to form the full package manifest:
+
+```cargo
+[dependencies]
+boolinator = "=0.1.0"
+```
+*/
+use boolinator::Boolinator;
+
+println!("--output--");
+println!("{:?}", true.as_some(1));

tests/data/script-full-line.rs

@@ -6,7 +6,6 @@ This is merged into a default manifest in order to form the full package manifes
 boolinator = "=0.1.0"
 ```
 */
-extern crate boolinator;
 use boolinator::Boolinator;
 fn main() {
     println!("--output--");

tests/data/script-short-without-main.rs

@@ -0,0 +1,9 @@
+// cargo-deps: boolinator="=0.1.0"
+// You can also leave off the version number, in which case, it's assumed
+// to be "*".  Also, the `cargo-deps` comment *must* be a single-line
+// comment, and it *must* be the first thing in the file, after the
+// hashbang.
+use boolinator::Boolinator;
+
+println!("--output--");
+println!("{:?}", true.as_some(1));

tests/data/script-short.rs

@@ -3,7 +3,6 @@
 // to be "*".  Also, the `cargo-deps` comment *must* be a single-line
 // comment, and it *must* be the first thing in the file, after the
 // hashbang.
-extern crate boolinator;
 use boolinator::Boolinator;
 fn main() {
     println!("--output--");

tests/tests/script.rs

@@ -37,6 +37,15 @@ fn test_script_full_line() {
     .unwrap()
 }
 
+#[test]
+fn test_script_full_line_without_main() {
+    let out = cargo_script!("tests/data/script-full-line-without-main.rs").unwrap();
+    scan!(out.stdout_output();
+        ("Some(1)") => ()
+    )
+    .unwrap()
+}
+
 #[test]
 fn test_script_invalid_doc_comment() {
     let out = cargo_script!("tests/data/script-invalid-doc-comment.rs").unwrap();
@@ -64,6 +73,15 @@ fn test_script_short() {
     .unwrap()
 }
 
+#[test]
+fn test_script_short_without_main() {
+    let out = cargo_script!("tests/data/script-short-without-main.rs").unwrap();
+    scan!(out.stdout_output();
+        ("Some(1)") => ()
+    )
+    .unwrap()
+}
+
 #[test]
 fn test_script_test() {
     let out = cargo_script!("--test", "tests/data/script-test.rs").unwrap();