UBSan diagnostics should say the name of the sanitizer

[davidben]

When enabling UBSan, you get errors that look like:

...: runtime error: reference binding to address ... with insufficient space for an object of type '...'

But this doesn't say which sanitizer option triggered that message. You have to grep for the error message in LLVM source, which can be difficult with line breaks and different chunks being assembled from different places. Reasons you might want to know the precise name of the sanitizer:

• Temporarily adding a fine-grained suppression without suppressing every sanitizer
• Look up more information about this particularly check (e.g. how does it know the size? is it compile-time information or runtime information?)

When Clang emits a warning, it says the name of the warning flag. It would be nice for sanitizer warnings to do the same.

[firewave]

You need to specify report_error_type=1 via the environment variable UBSAN_OPTIONS. See also #72060 for some shortcomings related to this.

[vitalybuka]

For years internally we use with report_error_type=1.
Should we switch the default?

[firewave]

For years internally we use with report_error_type=1. Should we switch the default?

I also see no point having it disabled by default - actually the whole option seems unnecessary to me.

[vitalybuka]

For years internally we use with report_error_type=1. Should we switch the default?

I also see no point having it disabled by default - actually the whole option seems unnecessary to me.

I suspect some users parse messages, and it may break parsing. So the option can be a quick workaround before parser update.

[davidben]

Oh nice! I had no idea that existed. Yeah, I'd definitely be in favor of turning it on by default. Seems maybe we should flip it on in Chromium in the meantime.