[rustdoc] Give more information into extracted doctest information

src/librustdoc/doctest.rs

@@ -1044,14 +1044,14 @@ fn doctest_run_fn(
     let report_unused_externs = |uext| {
         unused_externs.lock().unwrap().push(uext);
     };
-    let (full_test_code, full_test_line_offset) = doctest.generate_unique_doctest(
+    let (wrapper, full_test_line_offset) = doctest.generate_unique_doctest(
         &scraped_test.text,
         scraped_test.langstr.test_harness,
         &global_opts,
         Some(&global_opts.crate_name),
     );
     let runnable_test = RunnableDocTest {
-        full_test_code,
+        full_test_code: wrapper.to_string(),
         full_test_line_offset,
         test_opts,
         global_opts,

src/librustdoc/doctest/extracted.rs

@@ -5,6 +5,7 @@
 
 use serde::Serialize;
 
+use super::make::DocTestWrapResult;
 use super::{BuildDocTestBuilder, ScrapedDocTest};
 use crate::config::Options as RustdocOptions;
 use crate::html::markdown;
@@ -14,7 +15,7 @@ use crate::html::markdown;
 /// This integer is incremented with every breaking change to the API,
 /// and is returned along with the JSON blob into the `format_version` root field.
 /// Consuming code should assert that this value matches the format version(s) that it supports.
-const FORMAT_VERSION: u32 = 1;
+const FORMAT_VERSION: u32 = 2;
 
 #[derive(Serialize)]
 pub(crate) struct ExtractedDocTests {
@@ -42,7 +43,7 @@ impl ExtractedDocTests {
             .edition(edition)
             .lang_str(&langstr)
             .build(None);
-        let (full_test_code, size) = doctest.generate_unique_doctest(
+        let (wrapper, _size) = doctest.generate_unique_doctest(
             &text,
             langstr.test_harness,
             opts,
@@ -52,21 +53,46 @@ impl ExtractedDocTests {
             file: filename.prefer_remapped_unconditionaly().to_string(),
             line,
             doctest_attributes: langstr.into(),
-            doctest_code: if size != 0 { Some(full_test_code) } else { None },
+            doctest_code: match wrapper {
+                DocTestWrapResult::Valid { crate_level_code, wrapper, code } => Some(DocTest {
+                    crate_level: crate_level_code,
+                    code,
+                    wrapper: wrapper.map(
+                        |super::make::WrapperInfo { before, after, returns_result, .. }| {
+                            WrapperInfo { before, after, returns_result }
+                        },
+                    ),
+                }),
+                DocTestWrapResult::SyntaxError { .. } => None,
+            },
             original_code: text,
             name,
         });
     }
 }
 
+#[derive(Serialize)]
+pub(crate) struct WrapperInfo {
+    before: String,
+    after: String,
+    returns_result: bool,
+}
+
+#[derive(Serialize)]
+pub(crate) struct DocTest {
+    crate_level: String,
+    code: String,
+    wrapper: Option<WrapperInfo>,
+}
+
 #[derive(Serialize)]
 pub(crate) struct ExtractedDocTest {
     file: String,
     line: usize,
     doctest_attributes: LangString,
     original_code: String,
     /// `None` if the code syntax is invalid.
-    doctest_code: Option<String>,
+    doctest_code: Option<DocTest>,
     name: String,
 }
 

src/librustdoc/doctest/make.rs

@@ -184,6 +184,73 @@ pub(crate) struct DocTestBuilder {
     pub(crate) can_be_merged: bool,
 }
 
+/// Contains needed information for doctest to be correctly generated with expected "wrapping".
+pub(crate) struct WrapperInfo {
+    pub(crate) before: String,
+    pub(crate) after: String,
+    pub(crate) returns_result: bool,
+    insert_indent_space: bool,
+}
+
+impl WrapperInfo {
+    fn len(&self) -> usize {
+        self.before.len() + self.after.len()
+    }
+}
+
+/// Contains a doctest information. Can be converted into code with the `to_string()` method.
+pub(crate) enum DocTestWrapResult {
+    Valid {
+        crate_level_code: String,
+        wrapper: Option<WrapperInfo>,
+        code: String,
+    },
+    /// Contains the original source code.
+    SyntaxError(String),
+}
+
+impl std::string::ToString for DocTestWrapResult {
+    fn to_string(&self) -> String {
+        match self {
+            Self::SyntaxError(s) => s.clone(),
+            Self::Valid { crate_level_code, wrapper, code } => {
+                let mut prog_len = code.len() + crate_level_code.len();
+                if let Some(wrapper) = wrapper {
+                    prog_len += wrapper.len();
+                    if wrapper.insert_indent_space {
+                        prog_len += code.lines().count() * 4;
+                    }
+                }
+                let mut prog = String::with_capacity(prog_len);
+
+                prog.push_str(crate_level_code);
+                if let Some(wrapper) = wrapper {
+                    prog.push_str(&wrapper.before);
+
+                    // add extra 4 spaces for each line to offset the code block
+                    if wrapper.insert_indent_space {
+                        write!(
+                            prog,
+                            "{}",
+                            fmt::from_fn(|f| code
+                                .lines()
+                                .map(|line| fmt::from_fn(move |f| write!(f, "    {line}")))
+                                .joined("\n", f))
+                        )
+                        .unwrap();
+                    } else {
+                        prog.push_str(code);
+                    }
+                    prog.push_str(&wrapper.after);
+                } else {
+                    prog.push_str(code);
+                }
+                prog
+            }
+        }
+    }
+}
+
 impl DocTestBuilder {
     fn invalid(
         crate_attrs: String,
@@ -210,53 +277,53 @@ impl DocTestBuilder {
     /// lines before the test code begins.
     pub(crate) fn generate_unique_doctest(
         &self,
-        test_code: &str,
+        doctest_code: &str,
         dont_insert_main: bool,
         opts: &GlobalTestOptions,
         crate_name: Option<&str>,
-    ) -> (String, usize) {
+    ) -> (DocTestWrapResult, usize) {
         if self.invalid_ast {
             // If the AST failed to compile, no need to go generate a complete doctest, the error
             // will be better this way.
-            debug!("invalid AST:\n{test_code}");
-            return (test_code.to_string(), 0);
+            debug!("invalid AST:\n{doctest_code}");
+            return (DocTestWrapResult::SyntaxError(doctest_code.to_string()), 0);
         }
         let mut line_offset = 0;
-        let mut prog = String::new();
-        let everything_else = self.everything_else.trim();
+        let mut crate_level_code = String::new();
+        let processed_code = self.everything_else.trim().to_string();
         if opts.attrs.is_empty() {
             // If there aren't any attributes supplied by #![doc(test(attr(...)))], then allow some
             // lints that are commonly triggered in doctests. The crate-level test attributes are
             // commonly used to make tests fail in case they trigger warnings, so having this there in
             // that case may cause some tests to pass when they shouldn't have.
-            prog.push_str("#![allow(unused)]\n");
+            crate_level_code.push_str("#![allow(unused)]\n");
             line_offset += 1;
         }
 
         // Next, any attributes that came from the crate root via #![doc(test(attr(...)))].
         for attr in &opts.attrs {
-            prog.push_str(&format!("#![{attr}]\n"));
+            crate_level_code.push_str(&format!("#![{attr}]\n"));
             line_offset += 1;
         }
 
         // Now push any outer attributes from the example, assuming they
         // are intended to be crate attributes.
         if !self.crate_attrs.is_empty() {
-            prog.push_str(&self.crate_attrs);
+            crate_level_code.push_str(&self.crate_attrs);
             if !self.crate_attrs.ends_with('\n') {
-                prog.push('\n');
+                crate_level_code.push('\n');
             }
         }
         if !self.maybe_crate_attrs.is_empty() {
-            prog.push_str(&self.maybe_crate_attrs);
+            crate_level_code.push_str(&self.maybe_crate_attrs);
             if !self.maybe_crate_attrs.ends_with('\n') {
-                prog.push('\n');
+                crate_level_code.push('\n');
             }
         }
         if !self.crates.is_empty() {
-            prog.push_str(&self.crates);
+            crate_level_code.push_str(&self.crates);
             if !self.crates.ends_with('\n') {
-                prog.push('\n');
+                crate_level_code.push('\n');
             }
         }
 
@@ -270,21 +337,24 @@ impl DocTestBuilder {
             // NOTE: this is terribly inaccurate because it doesn't actually
             // parse the source, but only has false positives, not false
             // negatives.
-            test_code.contains(crate_name)
+            doctest_code.contains(crate_name)
         {
             // rustdoc implicitly inserts an `extern crate` item for the own crate
             // which may be unused, so we need to allow the lint.
-            prog.push_str("#[allow(unused_extern_crates)]\n");
+            crate_level_code.push_str("#[allow(unused_extern_crates)]\n");
 
-            prog.push_str(&format!("extern crate r#{crate_name};\n"));
+            crate_level_code.push_str(&format!("extern crate r#{crate_name};\n"));
             line_offset += 1;
         }
 
         // FIXME: This code cannot yet handle no_std test cases yet
-        if dont_insert_main || self.has_main_fn || prog.contains("![no_std]") {
-            prog.push_str(everything_else);
+        let wrapper = if dont_insert_main
+            || self.has_main_fn
+            || crate_level_code.contains("![no_std]")
+        {
+            None
         } else {
-            let returns_result = everything_else.ends_with("(())");
+            let returns_result = processed_code.ends_with("(())");
             // Give each doctest main function a unique name.
             // This is for example needed for the tooling around `-C instrument-coverage`.
             let inner_fn_name = if let Some(ref test_id) = self.test_id {
@@ -318,28 +388,15 @@ impl DocTestBuilder {
             // /// ``` <- end of the inner main
             line_offset += 1;
 
-            prog.push_str(&main_pre);
-
-            // add extra 4 spaces for each line to offset the code block
-            if opts.insert_indent_space {
-                write!(
-                    prog,
-                    "{}",
-                    fmt::from_fn(|f| everything_else
-                        .lines()
-                        .map(|line| fmt::from_fn(move |f| write!(f, "    {line}")))
-                        .joined("\n", f))
-                )
-                .unwrap();
-            } else {
-                prog.push_str(everything_else);
-            };
-            prog.push_str(&main_post);
-        }
-
-        debug!("final doctest:\n{prog}");
+            Some(WrapperInfo {
+                before: main_pre,
+                after: main_post,
+                returns_result,
+                insert_indent_space: opts.insert_indent_space,
+            })
+        };
 
-        (prog, line_offset)
+        (DocTestWrapResult::Valid { code: processed_code, wrapper, crate_level_code }, line_offset)
     }
 }
 

src/librustdoc/doctest/tests.rs

@@ -17,9 +17,9 @@ fn make_test(
         builder = builder.test_id(test_id.to_string());
     }
     let doctest = builder.build(None);
-    let (code, line_offset) =
+    let (wrapper, line_offset) =
         doctest.generate_unique_doctest(test_code, dont_insert_main, opts, crate_name);
-    (code, line_offset)
+    (wrapper.to_string(), line_offset)
 }
 
 /// Default [`GlobalTestOptions`] for these unit tests.

src/librustdoc/html/markdown.rs

@@ -308,7 +308,8 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'_, 'a, I> {
                 builder = builder.crate_name(krate);
             }
             let doctest = builder.build(None);
-            let (test, _) = doctest.generate_unique_doctest(&test, false, &opts, krate);
+            let (wrapped, _) = doctest.generate_unique_doctest(&test, false, &opts, krate);
+            let test = wrapped.to_string();
             let channel = if test.contains("#![feature(") { "&amp;version=nightly" } else { "" };
 
             let test_escaped = small_url_encode(test);

tests/rustdoc-ui/extract-doctests-result.rs

@@ -0,0 +1,11 @@
+// Test to ensure that it generates expected output for `--output-format=doctest` command-line
+// flag.
+
+//@ compile-flags:-Z unstable-options --output-format=doctest
+//@ normalize-stdout: "tests/rustdoc-ui" -> "$$DIR"
+//@ check-pass
+
+//! ```
+//! let x = 12;
+//! Ok(())
+//! ```

tests/rustdoc-ui/extract-doctests-result.stdout

@@ -0,0 +1 @@
+{"format_version":2,"doctests":[{"file":"$DIR/extract-doctests-result.rs","line":8,"doctest_attributes":{"original":"","should_panic":false,"no_run":false,"ignore":"None","rust":true,"test_harness":false,"compile_fail":false,"standalone_crate":false,"error_codes":[],"edition":null,"added_css_classes":[],"unknown":[]},"original_code":"let x = 12;\nOk(())","doctest_code":{"crate_level":"#![allow(unused)]\n","code":"let x = 12;\nOk(())","wrapper":{"before":"fn main() { fn _inner() -> core::result::Result<(), impl core::fmt::Debug> {\n","after":"\n} _inner().unwrap() }","returns_result":true}},"name":"$DIR/extract-doctests-result.rs - (line 8)"}]}

tests/rustdoc-ui/extract-doctests.stdout

@@ -1 +1 @@
-{"format_version":1,"doctests":[{"file":"$DIR/extract-doctests.rs","line":8,"doctest_attributes":{"original":"ignore (checking attributes)","should_panic":false,"no_run":false,"ignore":"All","rust":true,"test_harness":false,"compile_fail":false,"standalone_crate":false,"error_codes":[],"edition":null,"added_css_classes":[],"unknown":[]},"original_code":"let x = 12;\nlet y = 14;","doctest_code":"#![allow(unused)]\nfn main() {\nlet x = 12;\nlet y = 14;\n}","name":"$DIR/extract-doctests.rs - (line 8)"},{"file":"$DIR/extract-doctests.rs","line":13,"doctest_attributes":{"original":"edition2018,compile_fail","should_panic":false,"no_run":true,"ignore":"None","rust":true,"test_harness":false,"compile_fail":true,"standalone_crate":false,"error_codes":[],"edition":"2018","added_css_classes":[],"unknown":[]},"original_code":"let","doctest_code":null,"name":"$DIR/extract-doctests.rs - (line 13)"}]}
+{"format_version":2,"doctests":[{"file":"$DIR/extract-doctests.rs","line":8,"doctest_attributes":{"original":"ignore (checking attributes)","should_panic":false,"no_run":false,"ignore":"All","rust":true,"test_harness":false,"compile_fail":false,"standalone_crate":false,"error_codes":[],"edition":null,"added_css_classes":[],"unknown":[]},"original_code":"let x = 12;\nlet y = 14;","doctest_code":{"crate_level":"#![allow(unused)]\n","code":"let x = 12;\nlet y = 14;","wrapper":{"before":"fn main() {\n","after":"\n}","returns_result":false}},"name":"$DIR/extract-doctests.rs - (line 8)"},{"file":"$DIR/extract-doctests.rs","line":13,"doctest_attributes":{"original":"edition2018,compile_fail","should_panic":false,"no_run":true,"ignore":"None","rust":true,"test_harness":false,"compile_fail":true,"standalone_crate":false,"error_codes":[],"edition":"2018","added_css_classes":[],"unknown":[]},"original_code":"let","doctest_code":null,"name":"$DIR/extract-doctests.rs - (line 13)"}]}