[clang] Support custom crash/bug report messages #158203
Description
This bug carries over the discussion from #157536
Currently, when Clang crashes, it outputs the following message before emitting the stacktrace:
PLEASE submit a bug report to BUG_REPORT_URL and include the crash backtrace, preprocessed source, and associated run script.
However, some vendors may wish to modify this default message; for example, a vendor may wish to ask the user for additional information to reproduce the crash.
#157536 is an initial attempt; it works by simply allowing the user to set the entire contents of the error message in a macro. However, discussions on that PR suggests that this should be a downstream driven effort to create something flexible for everyone. Therefore, I created this bug to track improving Clang crash diagnostics for vendors.