Otherwise, we would strip away the `-o`, leaving the command line without any output path option and thus not able to generate a unit file (which requires an output path).
If a source file is part of multiple targets, we should index it in the context of all of those targets because the different targets may produce different USRs since they might use different build settings to interpret the file.
Do not apply the standardized file normalization to the source file itself. Otherwise we would get the following behavior:
- We have a build system that uses standardized file paths and index a file as /tmp/test.c
- We are asking for the main files of /private/tmp/test.c
- Since indexstore-db uses realpath for everything, we find the unit for /tmp/test.c as a unit containing /private/tmp/test.c, which has /private/tmp/test.c as the main file.
- If we applied the path normalization, we would normalize /private/tmp/test.c to /tmp/test.c, thus reporting that /tmp/test.c is a main file containing /private/tmp/test.c,
But that doesn't make sense (it would, in fact cause us to treat /private/tmp/test.c as a header file that we should index using /tmp/test.c as a main file.
This allows us to more easily test behavior for build servers that have different behavior than SwiftPM and compile commands without having to implement the build server in Python.
