[clang] [clang-tools-extra] [llvm] [clang-format] Add support for BasedOnStyle referencing an arbitrary file (PR #107312)

[via cfe-commits]

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@@ -39,6 +39,10 @@ IO::IO(void *Context) : Ctxt(Context) {}
 
 IO::~IO() = default;
 
+SourceMgr& IO::getSourceMgr() {
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mydeveloperday wrote:

This feels like an unrelated changes or change that could be done in isolation first

https://github.com/llvm/llvm-project/pull/107312