Fix #11885: Disable ANSI colors when stdout is piped on JDK 22+#11887
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… JDK 22+ Change ForcedSysOut to SysOut so that JLine properly checks whether stdout is a TTY before creating a system terminal. ForcedSysOut bypasses this check, which causes JLine to create a non-dumb terminal even when stdout is piped (since stdin is still a TTY), resulting in ANSI escape codes appearing in piped output on JDK 22+ where the FFM provider successfully creates a terminal from stdin alone. With SysOut, JLine detects that stdout is not a TTY and falls back to a dumb terminal, correctly disabling ANSI colors. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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…ted on JDK 22+ (apache#11887) Change ForcedSysOut to SysOut so that JLine properly checks whether stdout is a TTY before creating a system terminal. ForcedSysOut bypasses this check, which causes JLine to create a non-dumb terminal even when stdout is piped (since stdin is still a TTY), resulting in ANSI escape codes appearing in piped output on JDK 22+ where the FFM provider successfully creates a terminal from stdin alone. With SysOut, JLine detects that stdout is not a TTY and falls back to a dumb terminal, correctly disabling ANSI colors. Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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… JDK 22+ (#11887) (#12111) Change ForcedSysOut to SysOut so that JLine properly checks whether stdout is a TTY before creating a system terminal. ForcedSysOut bypasses this check, which causes JLine to create a non-dumb terminal even when stdout is piped (since stdin is still a TTY), resulting in ANSI escape codes appearing in piped output on JDK 22+ where the FFM provider successfully creates a terminal from stdin alone. With SysOut, JLine detects that stdout is not a TTY and falls back to a dumb terminal, correctly disabling ANSI colors. Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
ForcedSysOuttoSysOutin JLine'sTerminalBuilderconfiguration so that JLine properly checks whether stdout is a TTY before creating a system terminalForcedSysOutbypasses TTY detection, causing a non-dumb terminal to be created even when stdout is piped (because stdin is still a TTY), resulting in ANSI escape codes in piped output on JDK 22+ where the FFM provider creates a terminal from stdin aloneRoot Cause
JLine's
SystemOutput.ForcedSysOutalways returnsSystemStream.Outputinselect()without checking if stdout is actually a TTY. On JDK 21, the exec/JNI providers would fail to create a system terminal when stdout was piped, falling back to dumb. On JDK 22+ with the FFM provider, the terminal is created successfully (stdin is a TTY), producing a non-dumb terminal with colors enabled even when piped.SystemOutput.SysOutdoes the right thing: it checks if stdout is a TTY first. If not,systemStreamis null, and JLine falls back to a dumb terminal — exactly the correct behavior.Test plan
mvn help:help -X | lessshould show plain text (no ANSI codes) on JDK 25+mvn help:help -X > /tmp/out.txtshould produce plain text on JDK 25+mvn help:help -Xshould still show colored output on a real terminalmvn --color=always help:help -X | lessshould still show ANSI codes (forced)mvn --color=never help:help -Xshould show plain textFixes #11885
Claude Code on behalf of Guillaume Nodet
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