This commit removes a panic and replaces it with a proper source
location. The message still isn't very helpful, but at least it points
to a location in the source code.
I'm not very happy with all the `err.Error()` calls, but that's the way
to fit this in a `scanner.Error`. Eventually we should make a
replacement for `scanner.Error` that does proper wrapping of the
original error message.
This kind of code might be generated by the switch implementation of
func values. The func value is represented as a ptrtoint, and before
calling it, it is compared against 0.
This interpreter currently complements the Go SSA level interpreter. It
may stay complementary or may be the only interpreter in the future.
This interpreter is experimental and not yet finished (there are known
bugs!) so it is disabled by default. It can be enabled by passing the
-initinterp flag.
The goal is to be able to run all initializations at compile time except
for the ones having side effects. This mostly works except perhaps for a
few edge cases.
In the future, this interpeter may be used to actually run regular Go
code, perhaps in a shell.
