[clang-tools-extra] [clangd] Introduce --skip-preamble-build command line option (PR #189284)

[Chuanqi Xu via cfe-commits]

================
@@ -1005,6 +1013,16 @@ clangd accepts flags on the commandline, and in the CLANGD_FLAGS environment var
   }
   Opts.UseDirtyHeaders = UseDirtyHeaders;
   Opts.PreambleParseForwardingFunctions = PreambleParseForwardingFunctions;
+  if (ExperimentalModulesSupport &&
+      SkipPreambleBuild.getNumOccurrences() == 0) {
----------------
ChuanqiXu9 wrote:

Yeah, it is expected. A module unit doesn't contain import should be fine.

https://github.com/llvm/llvm-project/pull/189284