Commit `de23ccfad1`

Loris Cro <kappaloris@gmail.com>

2025-07-25 17:38:36

build system: print captured stderr on Run step failure

when a Run step that captures stderr fails, no output from it is visible by the user and, since the step failed, any downstream step that would process the captured stream will not run, making it impossible for the user to see the stderr output from the failed process invocation, which makes for a frustrating puzzle when this happens in CI.

master

1 parent eb1a497

Changed files (1)

lib

std

Build

Step

Run.zig

@@ -1391,6 +1391,16 @@ fn runCommand(
             }
         },
         else => {
+            // On failure, print stderr if captured.
+            const bad_exit = switch (result.term) {
+                .Exited => |code| code != 0,
+                .Signal, .Stopped, .Unknown => true,
+            };
+
+            if (bad_exit) if (result.stdio.stderr) |err| {
+                try step.addError("stderr:\n{s}", .{err});
+            };
+
             try step.handleChildProcessTerm(result.term, cwd, final_argv);
         },
     }

Commit de23ccfad1

Commit `de23ccfad1`