Use eprint! instead of eprintln!

Author: GuillaumeGomez

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/edition-2024-doctest-error-output.rs renamed to 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
+