Features to solve the problems with dll linking on Windows

Description of the problem / feature request:

Solving the problems with dll on Windows. If a package is dependent on 2 different dlls with the same name but different path, Bazel throw an error because it has to copy 2 dlls into the binary folder which causes name clash. The solution is renaming the dll to name-hash.dll and use a .lib file as an interface library and a .DEF file to actually point to the name-hash.dll

What operating system are you running Bazel on?

Windows 10

Have you found anything relevant by searching the web?

https://github.com/bazelbuild/bazel/issues/11482

Any other information, logs, or outputs that you want to share?

With the guidance of @meteorcloudy , I will implement this feature This is the progress tracker of this issue

• Add a build option to enable this features. --rename_dll
• Change the dll name on Windows to name-hash.dll, where hash will be calculated based on RepositoryName + the package path the DLL belongs to.
• Add the name to .DEF file by using LIBRARY name-hash
• Testing and document

[meteorcloudy]

You think it is better to make a PR for each progress or only one PR at the end.

Yes, I think you can implement it in one PR. But I’m not sure we should change CcBinary, because the target is defined explicitly by users, so they probably expect the DLL name to just be <name>.dll on Windows. However, the DLL built by cc_library is implicit when other cc_binary depends on it and specifies linkstatic = 0.

Does bazel use some kinds of linting ( clang-format, … ) ? I have not seen anything in the contributing guide

The code will be formatted when we import it into Google, but I don’t think the tools are available outside.

[vnghia]

And which version of Bazel were you using? It’s better to use newer version of Bazel. Old version may not be able to build the latest master branch.

Sorry, I use the bazel 2.0 to build. I use bazelisk and it fix the problem. Thank you