[llvm-dev] sancov reporting all locations as <invalid>:0

[Justin Bogner via llvm-dev]

I'm working on a fuzzer using libFuzzer and I wanted to take a look at
how my coverage was doing, as per the instructions here:

  http://llvm.org/docs/LibFuzzer.html#how-good-is-my-fuzzer

First of all, I suspect the instructions there are out of date, but
passing -dump_coverage=1 to the binary rather than setting ASAN_OPTIONS
generated a .sancov file for me.

However, when I inspect this with the sancov tool, all of the line
numbers it reports are "<invalid>:0". I can list the covered and
uncovered functions successfully, but without locations it's really hard
to do anything with that information.

I've built with -gline-tables-only, as is the default when building llvm
with sanitizers enabled.

Have you seen this before? Am I doing something obviously wrong?