Disallow interpretation of arbitrary calls in parameters

[nicolasstucki]

Only the macro call should be interpreted. The code within the parameters should only contain quoted code and literal constants.

inline def f(x: Expr[X]) = ${ impl('x) }
inline def f(x: Expr[X]) = ${ impl(doSomethong('x)) } // error

In the future, we could support having arbitrary code in the macros, but it should be done the right way. The code within the top-level splice should be precompiled and that code would be executed when calling the macro.

Migration

- inline def f(x: Expr[X]) = ${ impl(doSomethong('x)) } // error
+ inline def f(x: Expr[X]) = ${ impl0('x) } // interpreted code
+ private def impl0[X: Type](x: Expr[X])(using QuoteContext) = impl(doSomethong(x)) // compiled code

Future

Now that we have compilation unit suspension we could auto-generate the intermediary implementation and place it in a global object that gets compiled first. This is not a priority as it does not provide any extra functionality, it can always be written down explicitly.

[liufengyun]

LGTM