This is almost certainly related to the problem I encountered at Inline C: using stderr segfaults?. See the subthread starting at Re: Inline C: using stderr segfaults? that discovers that stderr is redefined to a complex macro expansion. stdout probably sufferes the same fate.

The most expedient and reliable solution I found was to use &_iob[2] for stderr and &_iob[1] for stdout when calling stdio routines from Inline C.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
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In reply to Re^5: Really, really suffering from buffering by BrowserUk
in thread Really, really suffering from buffering by syphilis

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