Running on Windows is broken because of symlink usage

[EFanZh]

To reproduce, run the following code with cmd:

set CARGO_INCREMENTAL=0
set RUSTFLAGS=-Zprofile -Ccodegen-units=1 -Copt-level=0 -Clink-dead-code -Coverflow-checks=off -Zpanic_abort_tests -Cpanic=abort
set RUSTDOCFLAGS=-Cpanic=abort

cargo +nightly new test-coverage --lib
cd test-coverage
cargo +nightly test

cargo +nightly install grcov
grcov ./target/debug/ -s . -t html --llvm --branch --ignore-not-existing -o ./target/debug/coverage/

start target/debug/coverage/src/lib.rs.html

There is no coverage on the report. Also, I have noticed that if I use nightly-gnu instead of nightly, the result is correct. Maybe the -Zprofile is not supported for msvc target?

System informantion:

• Compiler: rustc 1.46.0-nightly (50fc24d8a 2020-06-25)
• OS: Windows 10 version 2004 (OS Build 19041.329)

[howardmoore]

I've seen the same issue. I initially wondered if it was due to the use of --llvm, as I was linking with the MSVC linker, but removing that flag resulted in grcov reporting errors. Eventually I found that removing the -Cpanic=abort rustflag solved the problem. I also found I had to turn off control flow guard or my instrumented application crashed with a stack buffer overflow.

[marco-c]

I'll try to get to this as soon as I get my hands on a Windows machine.

[lolo32]

I've got another error on my Windows 10.

Without Administrator rights, it ends with:

18:53:08 [ERROR] A panic occurred at C:\Users\User\.cargo\registry\src\github.com-1ecc6299db9ec823\grcov-0.7.1\src\producer.rs:297: Failed to create a symlink "D:\\Projets\\rust\\test_cover\\.\\your_name-8644-12395990519104456799_0.profraw" -> "C:\\Users\\User\\AppData\\Local\\Temp\\.tmpxic1nO\\your_name-8644-12395990519104456799_0_1.profraw"

If running with admin rights because grcov want to do symlinks:

set LLVM_PROFILE_FILE=your_name-%p-%m.profraw
set RUSTFLAGS=-Zinstrument-coverage
cargo +nightly build
cargo +nightly test
grcov . --source-dir . --llvm --binary-path .\target\debug\ --branch --ignore-not-existing --ignore "/*" --output-type html --output-path .\target\debug\coverage

19:04:29 [ERROR] Error while executing llvm tools: Failed to execute "C:\\Users\\User\\.rustup\\toolchains\\nightly-x86_64-pc-windows-msvc\\lib\\rustlib\\x86_64-pc-windows-msvc\\bin\\llvm-profdata.exe" "merge" "-sparse" "C:\\Users\\User\\AppData\\Local\\Temp\\.tmpVTufXj\\your_name-8644-12395990519104456799_0_1.profraw" "C:\\Users\\User\\AppData\\Local\\Temp\\.tmpVTufXj\\default_1.profraw" "-o" "C:\\Users\\User\\AppData\\Local\\Temp\\.tmpVTufXj\\1\\grcov.profdata"
Le fichier spécifié est introuvable. (os error 2)

Sorry, the error message is in french like my interface. It says that grcov cannot find a file.

Versions informations:

• rustup 1.23.1 (3df2264a9 2020-11-30)
• cargo 1.51.0-nightly (ab64d1393 2021-02-10)
• rustc 1.52.0-nightly (07194ffcd 2021-02-10)
• grcov 0.7.1

[lolo32]

Sorry, i'm replying to my previous report, I forget to install llvm-tools-preview.

rustup component add llvm-tools-preview

Solved my previous problem, but I got another erro with the same command as the previous one:

19:58:28 [ERROR] Execution count overflow detected.

[marco-c]

@lolo32 does the report look OK? That error can be ignored in most cases.

[marco-c]

#720 should fix this.