It's helpful for stability to not have the path in the repo reflected in
test files, something I'm separately running into. So to reduce this,
align INCLUDE-FILE with other split behavior:
- Use the filename (with a "include_files/" subdir to disambiguate),
rather than the full path.
- Note if we eventually want to support splits in these, the same
approach could be extended.
- Only provide as an arg if the user requests files as args.
Factoring AddFile back because it's hard to share; I'm also advocating
to remove the prelude manifest, which would mean the remaining call
could be removed.
The INCLUDE-FILE option is only used in the toolchain tests for now. If
specified in a file test, the given file path is added to the test's
arguments. For toolchain tests this makes the file's package available
to the test. The `--custom-core` command line flag is added to the
driver, which avoids adding the production `Core` package to the command
line. Together, these allow a test to provide their own minimal `Core`
package.
For example, this would replace `Core` with the package and prelude in
`facet_types.carbon`.
```
// INCLUDE-FILE: toolchain/testing/min_prelude/facet_types.carbon
// EXTRA-ARGS: --custom-core
```
To support this:
* //testing knows how to parse INCLUDE-FILE out of the header of a test
file.
* //testing adds the file to the virtual file system, and includes it in
the test's arguments.
* //toolchain/driver grows the --custom-core command line flag to avoid
loading the production `Core` package.
Tests that were creating their own minimal prelude to define BitAnd on
types are now pointed to
toolchain/testing/min_prelude/facet_types.carbon as the prelude. They no
longer need to `import Core` in each test as a result.
Such tests are no longer `no_prelude`, but instead have their own
prelude. So they are moved to a `min_prelude` subdirectory.
Closes#5076
Jon Ross-Perkins
Dana Jansens