[clang] [CIR] Build out AST consumer patterns to reach the entry point into CIRGen (PR #91007)

[Aaron Ballman via cfe-commits]

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@@ -42,6 +47,14 @@ CreateFrontendBaseAction(CompilerInstance &CI) {
   StringRef Action("unknown");
   (void)Action;
 
+  auto UseCIR = CI.getFrontendOpts().UseClangIRPipeline;
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AaronBallman wrote:

Please follow the community conventions in this case because this is materially different from naming. With naming, it's about style and while it's quite distracting to have a unique style, it's doesn't really hurt understanding the code. With use of `auto`, it's about being able to understand the code for people not familiar with it; using `auto` in this way makes the code harder for the community to maintain in ways that naming conventions don't really have.

https://github.com/llvm/llvm-project/pull/91007