Add nonstring attribute to fix Clang build errors#282
Merged
mutability merged 1 commit intoflightaware:devfrom Mar 25, 2026
Merged
Add nonstring attribute to fix Clang build errors#282mutability merged 1 commit intoflightaware:devfrom
mutability merged 1 commit intoflightaware:devfrom
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These character arrays are intentionally sized to exactly fit their contents without a null terminator - they are used as lookup tables, not C strings. Modern Clang fails to build with -Werror due to -Wunterminated-string-initialization. The nonstring attribute documents the intent and silences the error without requiring global compiler flag changes.
This was referenced Mar 25, 2026
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Thanks, & sorry it took so long to get to this! |
This was referenced Mar 25, 2026
Closed
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This actually fails on clang-20, do you know the minimum clang version to support the attribute? https://github.com/flightaware/dump1090/actions/runs/23574105571/job/68642789458 (I'll put together some conditional compilation) |
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Mar 26, 2026
clang-20 complains by default about unrecognized attributes, so only include nonstring for >= 21 Do the same for gcc <10, since we don't do any testing on those older versions. This should fix some clang fallout from merging #282
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Could you check that the dev branch including 34ecd43 works okay on clang-21? (I don't have a clang-21 readily accessible) |
Author
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@mutability i checked llvm21/clang21 at commit 34ecd43 and it compiles successfully. i checked clang22 also and it works as well. you're all good now. |
Author
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nice macro. copied for my project https://github.com/zfogg/ascii-chat/blob/master/include/ascii-chat/common.h#L94-L99 |
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Summary
__attribute__((nonstring))to two character arrays that are intentionally sized without room for a null terminator-Werroris enabledDetails
The
ais_charset(64-char AIS lookup table) andspinner(4-char animation) arrays are used as raw byte lookup tables, not C strings. Clang's-Wunterminated-string-initializationwarning (promoted to error by-Werror) causes the build to fail.The
nonstringattribute is the idiomatic fix—it documents intent and is more targeted than disabling the warning globally via compiler flags.Test plan