The clang-scan-deps CLI tool invokes the compiler with -print-resource-dir in case the -resource-dir argument is missing from the compilation command line. This is to enable running the tool on compilation databases that use compiler from a different toolchain than clang-scan-deps itself. While this doesn't make sense when scanning modular builds (due to the -cc1 arguments the tool generates), the tool can can be used to efficiently scan for file dependencies of non-modular builds too.
This patch stops deducing the resource directory by invoking the compiler by default. This mode can still be enabled by invoking clang-scan-deps with --resource-dir-recipe invoke-compiler. The new default is --resource-dir-recipe modify-compiler-path which relies on the resource directory deduction taking place in Driver::Driver which is based on the compiler path. This makes the default more aligned with the intended usage of the tool while still allowing it to serve other use-cases.
Note that this functionality was also influenced by D108979, where the dependency scanner stopped going through ClangTool::run. The function tried to deduce the resource directory based on the current executable path, which might not be what the users expect when invoked from within a shared library.
Depends on D108979.