if you click on the OUTPUT tab, then on "V Language Server", make sure that you see something similar, i.e. that vscode uses VLS that is from /full/vls_path/bin/vls
> Building VLS... v -gc boehm -keepc -cg -cc gcc cmd/vls -o /home/den/wrk/lang/v/src/vls/git/vls/bin/vls builder error: Header file <gc.h>, needed for module builtin was not found. Please install the corresponding development headers. Failed building VLS