Want to turn off "note" level messages in GCC

Question

When I compile a C (no pluses) program using GCC, there are several levels of messages possible, like warning, error, and note. The note messages are useless and distracting. How do I make them go away using the command line? (I don't use any sort of IDE.)

Example: /home/user/src9/AllBack3.c:129:9: note: each undeclared identifier is reported only once for each function it appears in.

@mosvy, the man page makes `-fcompare-debug-second` sound a bit scary though: "When this option is passed to the compiler driver, it causes the first compilation to be skipped, which makes it useful for little other than debugging the compiler proper." — ilkkachu, Oct 19 '19 at 16:10
@mosvy I guess -fcompare-debug-second will have to do, if there's nothing else. If you put that in the form of an answer, I'll accept it. — Jennifer, Oct 20 '19 at 14:31
@ilkkachu notice that the second run of the compiler done by `-fcompare-debug` has nothing to do with the multiple compilation or optimization passes gcc may do -- as far as I can gather (I haven't used it myself), it's just a feature to debug the compiler itself (and create actionable bug reports). — , Oct 25 '19 at 22:02

score 7 · Accepted Answer · edited Jun 11 '20 at 14:16

7

Pass the -fcompare-debug-second option to gcc.

gcc's internal API has a diagnostic_inhibit_note() function which turns any "note:" messages off, but that is only serviceable via the unexpected -fcompare-debug-second command line switch, defined here.

Fortunately, turning notes off is its only effect, unless the -fcompare-debug or the -fdump-final-insns options are also used, which afaik are only for debugging the compiler itself.

edited Jun 11 '20 at 14:16

Community

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answered Oct 25 '19 at 21:58

`-fcompare-debug-second` also inhibits messages coming from `#pragma message`. How to keep `#pragma message` messages? – pmor Nov 04 '20 at 22:04
`#pragma message` generates a note message. Consider using `#warning` instead. – Nov 06 '20 at 01:13

score -3 · Answer 2 · answered Oct 26 '19 at 01:01

-3

You can use -w which also suppresses warnings.

For GCC, -w will not suppress the note you mentioned, probably because it is shown instead of another error. clang's -w on the other hand suppresses that too.

answered Oct 26 '19 at 01:01

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But I don't want to suppress warnings. – Jennifer Oct 30 '19 at 04:13

Want to turn off "note" level messages in GCC

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