Windows: backslashes are not supported in other "rc" files

[Fantasime]

Description of the bug:

Steps to reproduce the problem

Create a new workspace with the following structure:

workspace
├ main
| ├ BUILD
| └ hello_world.cc
├ .bazelrc
├ MODULE.bazel
└ user.bazelrc

In .bazelrc:

try-import user.bazelrc

In user.bazelrc:

startup --output_user_root="D:\Users\username\_bazel_username"

Then run:

bazel build

Problem description

OS: Windows

Bazel Version: 9.0.1

Error message:

[INFO 02:24:53.779 src/main/cpp/rc_file.cc:94] Parsing the RcFile ******/.bazelrc
[INFO 02:24:53.779 src/main/cpp/rc_file.cc:94] Parsing the RcFile user.bazelrc
[FATAL 02:24:53.780 src/main/cpp/util/path_windows.cc:85] MakeAbsolute(D:Usersusername_bazel_username): AsAbsoluteWindowsPath failed: working-directory relative paths are unsupported

Temporary solution

Modify user.bazelrc:

startup --output_user_root="D:/Users/username/_bazel_username"

[Fantasime]

I have corrected the title and content. A 100% reproducible way is presented.

[Fantasime]

It's not a bug. Bazel treats '\' as an escape character on all platforms.

Comment in src/main/cpp/rc_file.cc:

// This will treat "#" as a comment, and properly
// quote single and double quotes, and treat '\'
// as an escape character.
blaze_util::Tokenize(line, '#', &words);

The correct path seperator in the "rc" file is \\, so user.bazelrc in Steps to reproduce the problem should be modified:

startup --output_user_root="D:\\Users\\username\\_bazel_username"