`createExpansionLocImpl` has an assert that checks if we ran out of
source locations. We have observed this happening on real code and in
release builds the assertion does not fire and the compiler just keeps
running indefinitely without giving any indication that something went
wrong.
Diagnose this problem and reliably crash to make sure the problem is
easy to detect.
I have also tried:
- returning invalid source locations,
- reporting sloc address space usage on error.
Both caused the compiler to run indefinitely. It would be nice to dig
further why that happens, but until then crashing seems like a better
alternative.
Summary:
As discussed in http://lists.llvm.org/pipermail/cfe-dev/2019-October/063459.html
the overflow of the souce locations (limited to 2^31 chars) can generate all sorts of
weird things (bogus warnings, hangs, crashes, miscompilation and correct compilation).
In debug mode this assert would fail. So it might be a good start, as in PR42301,
to detect the failure and exit with a proper error message.
Reviewers: rsmith, thakis, miyuki
Reviewed By: miyuki
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D70183
