[clang] [clang][modules-driver] Add dependency scan and dependency graph (PR #152770)

[Michael Spencer via cfe-commits]

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@@ -99,5 +100,6 @@ add_clang_library(clangDriver
   LINK_LIBS
   clangBasic
   clangLex
+  clangDependencyScanning
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Bigcheese wrote:

As mentioned in my previous comment, this causes a cycle because clangDependencyScanning depends on clangDriver. This is fine when statically linking, but will fail with dynamic linking which we support.

This is only used by `DependencyScanningWorker::scanDependencies` to handle driver commands. To fix this I think it would be best to remove this dependency and instead have `scanDependencies` only work on frontend commands. I would then add a function to `clangDriver` that takes a `DependencyScanningWorker` and runs the scanner on all of frontend jobs, this would then be used to replace calls to `scanDependencies`.

This will need to be handled before this PR lands to avoid build issues.

https://github.com/llvm/llvm-project/pull/152770