Produces empty LCOV files since v0.9.0

[Minoru]

On Linux x86_64, I am getting the following LCOV file instead of the usual 920K of content:

TN:

Bisect results:

There are only 'skip'ped commits left to test.
The first bad commit could be any of:
ea325bdcffd4ccfd2692a5781b758d637202e4bf
16ee717f0e136cf3dea16649ad41c8485309cf8a
We cannot bisect more!

I had to git bisect skip the ea325bd because it panicked:

20:15:36 [ERROR] A panic occurred at src/llvm_tools.rs:94: called `Result::unwrap()` on an `Err` value: Error { kind: UnexpectedEof, message: "failed to fill whole buffer" }

I guess it was running into a file that's smaller than 128 bytes (in that commit, grcov used read_exact()).

The command line is:

grcov . --source-dir . --binary-path . --ignore-not-existing --ignore='/*' --ignore='3rd-party/*' --ignore='doc/*' --ignore='test/*' --ignore='target/*' --ignore='newsboat.cpp' --ignore='podboat.cpp' -t lcov -o coverage.lcov

I don't have a minimal reproducer yet (ran out of screen time for today), but it looks like the switch to infer crate broke some logic in grcov.

[marco-c]

@Minoru could you check with/without the two commits to figure out exactly which of the two is causing this?
If you can also have a minimal reproducer it would be ideal.

[tugtugtug]

Seeing the similar issue, empty outputs. I think it has to do with the silent auto inclusion of the gitignore file, which is intended to not allow submitting suff, but auto ignoring contents in that file makes no sense, as the binaries produced are obviously excluded from git submissions. deleting the .gitignore works. This is certainly a regression, .gitignore should not be automatically loaded.

0.8.24

$ ./grcov . --source-dir src --ignore "*cargo/registry/*" --ignore "/rustc/*" --branch --binary-path target/release/deps/ --output-types cobertura,html --output-path coverage --log-level DEBUG
03:43:42 [DEBUG] (1) globset: glob converted to regex: Glob { glob: "*cargo/registry/*", re: "(?-u)^.*cargo/registry/.*$", opts: GlobOptions { case_insensitive: false, literal_separator: false, backslash_escape: true, empty_alternates: false }, tokens: Tokens([ZeroOrMore, Literal('c'), Literal('a'), Literal('r'), Literal('g'), Literal('o'), Literal('/'), Literal('r'), Literal('e'), Literal('g'), Literal('i'), Literal('s'), Literal('t'), Literal('r'), Literal('y'), Literal('/'), ZeroOrMore]) }
03:43:42 [DEBUG] (1) globset: built glob set; 0 literals, 0 basenames, 0 extensions, 1 prefixes, 0 suffixes, 0 required extensions, 1 regexes

0.9.0

$ ./grcov . --source-dir src --ignore "*cargo/registry/*" --ignore "/rustc/*" --branch --binary-path target/release/deps/ --output-types cobertura,html --output-path coverage --log-level DEBUG
03:44:55 [DEBUG] (6) ignore::gitignore: opened gitignore file: /test/.gitignore
03:44:55 [DEBUG] (6) globset: glob converted to regex: Glob { glob: "**/target/**/*", re: "(?-u)^(?:/?|.*/)target(?:/|/.*/)[^/]*$", opts: GlobOptions { case_insensitive: false, literal_separator: true, backslash_escape: true, empty_alternates: false }, tokens: Tokens([RecursivePrefix, Literal('t'), Literal('a'), Literal('r'), Literal('g'), Literal('e'), Literal('t'), RecursiveZeroOrMore, ZeroOrMore]) }
03:44:55 [DEBUG] (6) globset: glob converted to regex: Glob { glob: "istio-*/**/*", re: "(?-u)^istio\\-[^/]*(?:/|/.*/)[^/]*$", opts: GlobOptions { case_insensitive: false, literal_separator: true, backslash_escape: true, empty_alternates: false }, tokens: Tokens([Literal('i'), Literal('s'), Literal('t'), Literal('i'), Literal('o'), Literal('-'), ZeroOrMore, RecursiveZeroOrMore, ZeroOrMore]) }
03:44:55 [DEBUG] (6) globset: built glob set; 0 literals, 2 basenames, 0 extensions, 0 prefixes, 0 suffixes, 0 required extensions, 2 regexes
03:44:55 [DEBUG] (6) ignore::gitignore: opened gitignore file: /test/.git/info/exclude
03:44:55 [DEBUG] (6) ignore::walk: ignoring target/release/deps/memchr-d3c92593497a8663.d: Ignore(IgnoreMatch(Gitignore(Glob { from: Some("/test/.gitignore"), original: "**/target/**", actual: "**/target/**/*", is_whitelist: false, is_only_dir: false })))
...

$ cat coverage/cobertura.xml
<?xml version="1.0"?><!DOCTYPE  coverage SYSTEM 'http://cobertura.sourceforge.net/xml/coverage-04.dtd'><coverage lines-covered="0" lines-valid="0" line-rate="0" branches-covered="0" branches-valid="0" branch-rate="0" complexity="0" version="1.9" timestamp="1748058295"><sources><source>/test/transform-filter/src</source></sources><packages></packages></coverage

[tugtugtug]

@marco-c it is 16ee717, which introduced the ignore dependency.

[marco-c]

@tugtugtug thanks for investigating. It should just be a matter of calling https://docs.rs/ignore/latest/ignore/struct.WalkBuilder.html#method.standard_filters on the WalkBuilder to set them to false.
It'd be great if you could test that and submit a PR!

[tugtugtug]

@tugtugtug thanks for investigating. It should just be a matter of calling https://docs.rs/ignore/latest/ignore/struct.WalkBuilder.html#method.standard_filters on the WalkBuilder to set them to false. It'd be great if you could test that and submit a PR!

I'm a bit confused tho, @marco-c so we end up with the standard filters disabled for the WalkBuilder, and do not really ignore anything? So isn't the ignore dependency overkill for what we need? which is probably achievable already with rayon (which is part of the dependencies already)?

[marco-c]

The only reason for using ignore is to have parallel walk of directories. We could implement it manually, but it would be quite some effort compared to just using ignore.

[marco-c]

I mean, I'd likely* accept a PR to implement parallel walking directly in grcov without ignore, but we can just fix this bug quickly for now by setting that option to false.

* unless it is too much code and too complex code

[tugtugtug]

@marco-c hopefully, this change fits in the not "too much code" category. The walker implementation is less than 150 lines. All tests passed in the PR, and I verified with the benchmarks on my mac, it performs slightly better than the original ignore lib with the standard filter disabled.