[clang-tools-extra] [clangd] Expand response files before CDB interpolation (PR #75753)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

@twmht To my knowledge, clang and clangd have only ever supported the `@file.rsp` response file syntax.

The commands in the linked thread use the `--options-file file.rsp` syntax, which clang and clangd do not support. https://github.com/clangd/vscode-clangd/issues/592 is on file about this, but please note that clangd is unlikely to add support for this syntax without the clang driver itself adding support first.

https://github.com/llvm/llvm-project/pull/75753