add extra indent spaces for rust-playground link

src/librustdoc/doctest.rs

@@ -40,6 +40,9 @@
 pub(crate) struct GlobalTestOptions {
     /// Whether to disable the default `extern crate my_crate;` when creating doctests.
     pub(crate) no_crate_inject: bool,
+    /// Whether inserting extra indent spaces in code block,
+    /// default is `false`, only `true` for generating code link of Rust playground
+    pub(crate) insert_indent_space: bool,
     /// Additional crate-level attributes to add to doctests.
     pub(crate) attrs: Vec<String>,
 }
@@ -221,7 +224,8 @@ pub(crate) fn run_tests(
 fn scrape_test_config(attrs: &[ast::Attribute]) -> GlobalTestOptions {
     use rustc_ast_pretty::pprust;
 
-    let mut opts = GlobalTestOptions { no_crate_inject: false, attrs: Vec::new() };
+    let mut opts =
+        GlobalTestOptions { no_crate_inject: false, attrs: Vec::new(), insert_indent_space: false };
 
     let test_attrs: Vec<_> = attrs
         .iter()
@@ -725,7 +729,17 @@ pub(crate) fn make_test(
         // /// ``` <- end of the inner main
         line_offset += 1;
 
-        prog.extend([&main_pre, everything_else, &main_post].iter().cloned());
+        // add extra 4 spaces for each line to offset the code block
+        let content = if opts.insert_indent_space {
+            everything_else
+                .lines()
+                .map(|line| format!("    {}", line))
+                .collect::<Vec<String>>()
+                .join("\n")
+        } else {
+            everything_else.to_string()
+        };
+        prog.extend([&main_pre, content.as_str(), &main_post].iter().cloned());
     }
 
     debug!("final doctest:\n{prog}");

src/librustdoc/doctest/tests.rs

@@ -53,7 +53,8 @@ fn main() {
 fn make_test_no_crate_inject() {
     // Even if you do use the crate within the test, setting `opts.no_crate_inject` will skip
     // adding it anyway.
-    let opts = GlobalTestOptions { no_crate_inject: true, attrs: vec![] };
+    let opts =
+        GlobalTestOptions { no_crate_inject: true, attrs: vec![], insert_indent_space: false };
     let input = "use asdf::qwop;
 assert_eq!(2+2, 4);";
     let expected = "#![allow(unused)]
@@ -302,3 +303,44 @@ fn main() { #[allow(non_snake_case)] fn _doctest_main__some_unique_name() {
         make_test(input, None, false, &opts, DEFAULT_EDITION, Some("_some_unique_name"));
     assert_eq!((output, len), (expected, 2));
 }
+
+#[test]
+fn make_test_insert_extra_space() {
+    // will insert indent spaces in the code block if `insert_indent_space` is true
+    let opts =
+        GlobalTestOptions { no_crate_inject: false, attrs: vec![], insert_indent_space: true };
+    let input = "use std::*;
+assert_eq!(2+2, 4);
+eprintln!(\"hello anan\");
+";
+    let expected = "#![allow(unused)]
+fn main() {
+    use std::*;
+    assert_eq!(2+2, 4);
+    eprintln!(\"hello anan\");
+}"
+    .to_string();
+    let (output, len, _) = make_test(input, None, false, &opts, DEFAULT_EDITION, None);
+    assert_eq!((output, len), (expected, 2));
+}
+
+#[test]
+fn make_test_insert_extra_space_fn_main() {
+    // if input already has a fn main, it should insert a space before it
+    let opts =
+        GlobalTestOptions { no_crate_inject: false, attrs: vec![], insert_indent_space: true };
+    let input = "use std::*;
+fn main() {
+    assert_eq!(2+2, 4);
+    eprintln!(\"hello anan\");
+}";
+    let expected = "#![allow(unused)]
+use std::*;
+fn main() {
+    assert_eq!(2+2, 4);
+    eprintln!(\"hello anan\");
+}"
+    .to_string();
+    let (output, len, _) = make_test(input, None, false, &opts, DEFAULT_EDITION, None);
+    assert_eq!((output, len), (expected, 1));
+}

src/librustdoc/html/markdown.rs

@@ -45,6 +45,7 @@
 
 use crate::clean::RenderedLink;
 use crate::doctest;
+use crate::doctest::GlobalTestOptions;
 use crate::html::escape::Escape;
 use crate::html::format::Buffer;
 use crate::html::highlight;
@@ -302,8 +303,10 @@ fn next(&mut self) -> Option<Self::Item> {
                 .intersperse("\n".into())
                 .collect::<String>();
             let krate = krate.as_ref().map(|s| s.as_str());
-            let (test, _, _) =
-                doctest::make_test(&test, krate, false, &Default::default(), edition, None);
+
+            let mut opts: GlobalTestOptions = Default::default();
+            opts.insert_indent_space = true;
+            let (test, _, _) = doctest::make_test(&test, krate, false, &opts, edition, None);
             let channel = if test.contains("#![feature(") { "&amp;version=nightly" } else { "" };
 
             let test_escaped = small_url_encode(test);

tests/rustdoc/playground-arg.rs

@@ -10,4 +10,4 @@
 pub fn dummy() {}
 
 // ensure that `extern crate foo;` was inserted into code snips automatically:
-// @matches foo/index.html '//a[@class="test-arrow"][@href="https://example.com/?code=%23!%5Ballow(unused)%5D%0A%23%5Ballow(unused_extern_crates)%5D%0Aextern+crate+r%23foo;%0Afn+main()+%7B%0Ause+foo::dummy;%0Adummy();%0A%7D&edition=2015"]' "Run"
+// @matches foo/index.html '//a[@class="test-arrow"][@href="https://example.com/?code=%23!%5Ballow(unused)%5D%0A%23%5Ballow(unused_extern_crates)%5D%0Aextern+crate+r%23foo;%0Afn+main()+%7B%0A++++use+foo::dummy;%0A++++dummy();%0A%7D&edition=2015"]' "Run"

tests/rustdoc/playground.rs

@@ -22,6 +22,6 @@
 //! }
 //! ```
 
-// @matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0Afn+main()+%7B%0Aprintln!(%22Hello,+world!%22);%0A%7D&edition=2015"]' "Run"
+// @matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&edition=2015"]' "Run"
 // @matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&edition=2015"]' "Run"
 // @matches foo/index.html '//a[@class="test-arrow"][@href="https://www.example.com/?code=%23!%5Ballow(unused)%5D%0A%23!%5Bfeature(something)%5D%0A%0Afn+main()+%7B%0A++++println!(%22Hello,+world!%22);%0A%7D&version=nightly&edition=2015"]' "Run"