Please describe the problem.
For hints on what information is helpful, see: https://clangd.llvm.org/troubleshooting.html

If you can, provide a minimal chunk of code that shows the problem (either inline, or attach it if larger).

As shown in the pictures above, clangd cannot recognize that the old references also adapt to the new function, when I append int parameter a with default value 1.

Logs

Please attach the clangd stderr log if you can. (Usually available from the editor)
If possible, run with --log=verbose - note that the logs will include the contents of open files!
If this is a crash, try to put llvm-symbolizer on your PATH per the troubleshooting instructions.

System information

Output of clangd --version:

Editor/LSP plugin:
vscode-clangd
Operating system:
mac intel