Use eprint! instead of eprintln!

src/librustdoc/doctest/runner.rs

@@ -131,7 +131,7 @@ mod __doctest_mod {{
             .output()
             .expect(\"failed to run command\");
         if !out.status.success() {{
-            eprintln!(\"{{}}\", String::from_utf8_lossy(&out.stderr));
+            eprint!(\"{{}}\", String::from_utf8_lossy(&out.stderr));
             ExitCode::FAILURE
         }} else {{
             ExitCode::SUCCESS

tests/rustdoc-ui/doctest/edition-2024-error-output.rs

@@ -4,7 +4,9 @@
 //@ edition: 2024
 //@ compile-flags: --test
 //@ normalize-stdout: "tests/rustdoc-ui/doctest" -> "$$DIR"
+//@ normalize-stdout: "panicked at .+rs:" -> "panicked at $$TMP:"
 //@ normalize-stdout: "finished in \d+\.\d+s" -> "finished in $$TIME"
+//@ rustc-env:RUST_BACKTRACE=0
 //@ failure-status: 101
 
 //! ```rust

tests/rustdoc-ui/doctest/edition-2024-error-output.stdout

@@ -0,0 +1,20 @@
+
+running 1 test
+test $DIR/edition-2024-error-output.rs - (line 12) ... FAILED
+
+failures:
+
+---- $DIR/edition-2024-error-output.rs - (line 12) stdout ----
+
+thread 'main' panicked at $TMP:6:1:
+assertion `left == right` failed
+  left: 4
+ right: 5
+note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
+
+
+failures:
+    $DIR/edition-2024-error-output.rs - (line 12)
+
+test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
+

tests/rustdoc-ui/edition-2024-doctest-error-output.stdout

@@ -1,32 +0,0 @@
-
-running 1 test
-test tests/rustdoc-ui/edition-2024-doctest-error-output.rs - (line 10) ... FAILED
-
-failures:
-
----- tests/rustdoc-ui/edition-2024-doctest-error-output.rs - (line 10) stdout ----
-
-thread 'main' panicked at /tmp/rustdoctestSZq9aS/doctest_bundle_2024.rs:6:1:
-assertion `left == right` failed
-  left: 4
- right: 5
-stack backtrace:
-   0: __rustc::rust_begin_unwind
-   1: core::panicking::panic_fmt
-   2: core::panicking::assert_failed_inner
-   3: core::panicking::assert_failed
-   4: doctest_bundle_2024::__doctest_0::main
-   5: doctest_bundle_2024::__doctest_0::__main_fn
-   6: doctest_runner_2024::__doctest_0::TEST::{{closure}}
-   7: core::ops::function::FnOnce::call_once
-   8: doctest_runner_2024::main
-   9: core::ops::function::FnOnce::call_once
-note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
-
-
-
-failures:
-    tests/rustdoc-ui/edition-2024-doctest-error-output.rs - (line 10)
-
-test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0 filtered out; finished in $TIME
-