11 files changed, 86 insertions, 1 deletions
diff --git a/src/doc/rustdoc/src/command-line-arguments.md b/src/doc/rustdoc/src/command-line-arguments.md
index 2e4016e24bc..c8af369a969 100644
--- a/src/doc/rustdoc/src/command-line-arguments.md
+++ b/src/doc/rustdoc/src/command-line-arguments.md
@@ -417,3 +417,10 @@ This flag is **deprecated** and **has no effect**.
 Rustdoc only supports Rust source code and Markdown input formats. If the
 file ends in `.md` or `.markdown`, `rustdoc` treats it as a Markdown file.
 Otherwise, it assumes that the input file is Rust.
+
+## `--nocapture`
+
+When this flag is used with `--test`, the output (stdout and stderr) of your tests won't be
+captured by rustdoc. Instead, the output will be directed to your terminal,
+as if you had run the test executable manually. This is especially useful
+for debugging your tests!
diff --git a/src/librustdoc/config.rs b/src/librustdoc/config.rs
index 4cf647a81ae..adbdde0d92c 100644
--- a/src/librustdoc/config.rs
+++ b/src/librustdoc/config.rs
@@ -156,6 +156,8 @@ crate struct Options {
     crate run_check: bool,
     /// Whether doctests should emit unused externs
     crate json_unused_externs: bool,
+    /// Whether to skip capturing stdout and stderr of tests.
+    crate nocapture: bool,
 }
 
 impl fmt::Debug for Options {
@@ -199,6 +201,7 @@ impl fmt::Debug for Options {
             .field("enable-per-target-ignores", &self.enable_per_target_ignores)
             .field("run_check", &self.run_check)
             .field("no_run", &self.no_run)
+            .field("nocapture", &self.nocapture)
             .finish()
     }
 }
@@ -627,6 +630,7 @@ impl Options {
         let run_check = matches.opt_present("check");
         let generate_redirect_map = matches.opt_present("generate-redirect-map");
         let show_type_layout = matches.opt_present("show-type-layout");
+        let nocapture = matches.opt_present("nocapture");
 
         let (lint_opts, describe_lints, lint_cap, _) =
             get_cmd_lint_options(matches, error_format, &debugging_opts);
@@ -665,6 +669,7 @@ impl Options {
             test_builder,
             run_check,
             no_run,
+            nocapture,
             render_options: RenderOptions {
                 output,
                 external_html,
diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
index c5ca396e720..5ce7c49278d 100644
--- a/src/librustdoc/doctest.rs
+++ b/src/librustdoc/doctest.rs
@@ -107,6 +107,7 @@ crate fn run(options: Options) -> Result<(), ErrorReported> {
 
     let mut test_args = options.test_args.clone();
     let display_warnings = options.display_warnings;
+    let nocapture = options.nocapture;
     let externs = options.externs.clone();
     let json_unused_externs = options.json_unused_externs;
 
@@ -166,6 +167,9 @@ crate fn run(options: Options) -> Result<(), ErrorReported> {
     };
 
     test_args.insert(0, "rustdoctest".to_string());
+    if nocapture {
+        test_args.push("--nocapture".to_string());
+    }
 
     test::test_main(&test_args, tests, Some(test::Options::new().display_output(display_warnings)));
 
@@ -456,7 +460,16 @@ fn run_test(
         cmd.current_dir(run_directory);
     }
 
-    match cmd.output() {
+    let result = if options.nocapture {
+        cmd.status().map(|status| process::Output {
+            status,
+            stdout: Vec::new(),
+            stderr: Vec::new(),
+        })
+    } else {
+        cmd.output()
+    };
+    match result {
         Err(e) => return Err(TestFailure::ExecutionError(e)),
         Ok(out) => {
             if should_panic && out.status.success() {
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index d4d87819c0d..19deaa11388 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -604,6 +604,9 @@ fn opts() -> Vec<RustcOptGroup> {
         unstable("show-type-layout", |o| {
             o.optflagmulti("", "show-type-layout", "Include the memory layout of types in the docs")
         }),
+        unstable("nocapture", |o| {
+            o.optflag("", "nocapture", "Don't capture stdout and stderr of tests")
+        }),
     ]
 }
 
diff --git a/src/librustdoc/markdown.rs b/src/librustdoc/markdown.rs
index 45966c0058d..6c8b95c04c9 100644
--- a/src/librustdoc/markdown.rs
+++ b/src/librustdoc/markdown.rs
@@ -136,6 +136,9 @@ crate fn test(mut options: Options) -> Result<(), String> {
     find_testable_code(&input_str, &mut collector, codes, options.enable_per_target_ignores, None);
 
     options.test_args.insert(0, "rustdoctest".to_string());
+    if options.nocapture {
+        options.test_args.push("--nocapture".to_string());
+    }
     test::test_main(
         &options.test_args,
         collector.tests,
diff --git a/src/test/rustdoc-ui/nocapture-fail.rs b/src/test/rustdoc-ui/nocapture-fail.rs
new file mode 100644
index 00000000000..7706bd1f3e3
--- /dev/null
+++ b/src/test/rustdoc-ui/nocapture-fail.rs
@@ -0,0 +1,12 @@
+// check-pass
+// compile-flags:--test -Zunstable-options --nocapture
+// normalize-stderr-test: "src/test/rustdoc-ui" -> "$$DIR"
+// normalize-stdout-test: "src/test/rustdoc-ui" -> "$$DIR"
+// normalize-stdout-test "finished in \d+\.\d+s" -> "finished in $$TIME"
+
+/// ```compile_fail
+/// fn foo() {
+///     Input: 123
+/// }
+/// ```
+pub struct Foo;
diff --git a/src/test/rustdoc-ui/nocapture-fail.stderr b/src/test/rustdoc-ui/nocapture-fail.stderr
new file mode 100644
index 00000000000..16a5ac47cd2
--- /dev/null
+++ b/src/test/rustdoc-ui/nocapture-fail.stderr
@@ -0,0 +1,18 @@
+error: struct literal body without path
+  --> $DIR/nocapture-fail.rs:8:10
+   |
+LL |   fn foo() {
+   |  __________^
+LL | |     Input: 123
+LL | | }
+   | |_^
+   |
+help: you might have forgotten to add the struct literal inside the block
+   |
+LL | fn foo() { SomeStruct {
+LL |     Input: 123
+LL | } }
+   |
+
+error: aborting due to previous error
+
diff --git a/src/test/rustdoc-ui/nocapture-fail.stdout b/src/test/rustdoc-ui/nocapture-fail.stdout
new file mode 100644
index 00000000000..754f77db53c
--- /dev/null
+++ b/src/test/rustdoc-ui/nocapture-fail.stdout
@@ -0,0 +1,6 @@
+
+running 1 test
+test $DIR/nocapture-fail.rs - Foo (line 7) - compile fail ... ok
+
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
+
diff --git a/src/test/rustdoc-ui/nocapture.rs b/src/test/rustdoc-ui/nocapture.rs
new file mode 100644
index 00000000000..321f5ca08ed
--- /dev/null
+++ b/src/test/rustdoc-ui/nocapture.rs
@@ -0,0 +1,10 @@
+// check-pass
+// compile-flags:--test -Zunstable-options --nocapture
+// normalize-stdout-test: "src/test/rustdoc-ui" -> "$$DIR"
+// normalize-stdout-test "finished in \d+\.\d+s" -> "finished in $$TIME"
+
+/// ```
+/// println!("hello!");
+/// eprintln!("stderr");
+/// ```
+pub struct Foo;
diff --git a/src/test/rustdoc-ui/nocapture.stderr b/src/test/rustdoc-ui/nocapture.stderr
new file mode 100644
index 00000000000..af6415db3c7
--- /dev/null
+++ b/src/test/rustdoc-ui/nocapture.stderr
@@ -0,0 +1 @@
+stderr
diff --git a/src/test/rustdoc-ui/nocapture.stdout b/src/test/rustdoc-ui/nocapture.stdout
new file mode 100644
index 00000000000..4880e75da70
--- /dev/null
+++ b/src/test/rustdoc-ui/nocapture.stdout
@@ -0,0 +1,7 @@
+
+running 1 test
+hello!
+test $DIR/nocapture.rs - Foo (line 6) ... ok
+
+test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
+