Hi!
When I add precompilation statements from SnoopCompile, I start to see weird coverage results. Take a look here:
Everything seems fine when I remove those statements.
I saw that this can be improved if I run Julia with --inline=no when generating the coverage information. However, I am using the Github action julia-actions/julia-processcoverage@v1. Can anyone tell me what can I do to add this --inline=no option to that Github action?
That action actually just collects coverage files already generated by previous steps in your workflow, most likely from julia-actions/julia-runtest. To add --inline=no there, you change
- uses: julia-actions/julia-runtest@v1
to
- uses: julia-actions/julia-runtest@v1
with:
inline: no
Note: some code heavily depends on inlining for performance. I saw a test go from a few seconds to 300s+ with --inline=no! So you might want to be careful where you use it.
Thanks @ericphanson !
It does not have any time impact. However, the coverage did not improve 
I am still seeing things like this if I use precompilation directives:
I am wondering if I can remove the precompilation if I am running for coverage computation.
It is ugly, but seems to work:
First, I add the precompilation directive as follows:
if Base.VERSION >= v"1.4.2" && !haskey(ENV, "STRING_MANIPULATION_NO_PRECOMPILATION")
# This try/catch is necessary in case the precompilation statements do not
# exists. In this case, StringManipulation.jl will work correctly but
# without the optimizations.
try
include("../precompilation/precompile_StringManipulation.jl")
_precompile_()
catch
end
end
Then, I removed the coverage processing from the main GitHub action.
After that, I create another action for the coverage using the following file:
name: Coverage
on:
pull_request:
branches:
- main
push:
branches:
- main
tags: '*'
jobs:
test:
name: Julia ${{ matrix.version }} - ${{ matrix.os }} - ${{ matrix.arch }} - ${{ github.event_name }}
runs-on: ${{ matrix.os }}
strategy:
fail-fast: false
matrix:
version:
- '1' # This automatically expands to the latest stable 1.x release.
os:
- ubuntu-latest
arch:
- x64
env:
STRING_MANIPULATION_NO_PRECOMPILATION: ""
steps:
- uses: actions/checkout@v2
- uses: julia-actions/setup-julia@v1
with:
version: ${{ matrix.version }}
arch: ${{ matrix.arch }}
- uses: actions/cache@v1
env:
cache-name: cache-artifacts
with:
path: ~/.julia/artifacts
key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ hashFiles('**/Project.toml') }}
restore-keys: |
${{ runner.os }}-test-${{ env.cache-name }}-
${{ runner.os }}-test-
${{ runner.os }}-
- uses: julia-actions/julia-buildpkg@v1
- uses: julia-actions/julia-runtest@v1
- uses: julia-actions/julia-processcoverage@v1
- uses: codecov/codecov-action@v2
with:
file: lcov.info
And now everything works 
It would be interesting to know if this also happens on nightly, which has major changes to precompilation.
Off the top of my head, the most likely culprit may be constant-propagation, and if different code gets generated depending on whether you precompile.
