[clang-tools-extra] [clangd] Implement simple folding of preprocessor branches (rebased) (PR #121449)

[Nathan Ridge via cfe-commits]

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@@ -124,6 +124,9 @@ llvm::raw_ostream &operator<<(llvm::raw_ostream &,
 /// The choices are stored in Conditional::Taken nodes.
 void chooseConditionalBranches(DirectiveTree &, const TokenStream &Code);
 
+std::vector<Token::Range> pairDirectiveRanges(const DirectiveTree &Tree,
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HighCommander4 wrote:

Please add a documentation comment similar to other function declarations in this header

https://github.com/llvm/llvm-project/pull/121449