Is returning a value != '0' or '1' as jboolean from a JNI function legal? (original) (raw)
Andrew Haley aph at redhat.com
Mon Aug 20 17:23:49 UTC 2018
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On 08/20/2018 04:14 PM, Jason Greene wrote:
IMO departing from C semantics (non-zero = TRUE, zero = false) offers little gain and will likely just lead to hard to catch bugs. Even if the JNI developer knows the rules, it will be quite easy for surprises to show up. For example, a developer might assume a library call always returns 1, and wire it straight to a boolean. If this assumption is broken (a condition not taken into account, or future behavioral differences), then it could quickly turn into a lot of wasted time and effort.
It's tricky, though: a C implementation could silently truncate a value of 0xff00_0000 to (jboolean) 0x00, and there's not a damn thing that a JVM can do about it: there's literally no way to know. It's pretty much unfixable from our end.
-- Andrew Haley Java Platform Lead Engineer Red Hat UK Ltd. <https://www.redhat.com> EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671
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