This change introduces a new informational message category to the
overall diagnostics infrastructure, and then wires up the resource
provider plugins stdout/stderr streams to it. In particular, a
write to stdout implies an informational message, whereas a write to
stderr implies an error. This is just a very simple and convenient
way for plugins to provide progress reporting; eventually we may
need something more complex, due to parallel evaluation of resource
graphs, however I hope we don't have to deviate too much from this.
This change redoes the way module exports are represented. The old
mechanism -- although laudible for its attempt at consistency -- was
wrong. For example, consider this case:
let v = 42;
export { v };
The old code would silently add *two* members, both with the name "v",
one of which would be dropped since the entries in the map collided.
It would be easy enough just to detect collisions, and update the
above to mark "v" as public, when the export was encountered. That
doesn't work either, as the following two examples demonstrate:
let v = 42;
export { v as w };
let x = w; // error!
This demonstrates:
* Exporting "v" with a different name, "w" to consumers of the
module. In particular, it should not be possible for module
consumers to access the member through the name "v".
* An inability to access the exported name "w" from within the
module itself. This is solely for external consumption.
Because of this, we will use an export table approach. The exports
live alongside the members, and we are smart about when to consult
the export table, versus the member table, during name binding.
This change revives some compiler tests that are still lingering around
from the old architecture, before our latest round of ship burning.
It also fixes up some bugs uncovered during this:
* Don't claim that a symbol's kind is incorrect in the binder error
message when it wasn't found. Instead, say that it was missing.
* Do not attempt to compile if an error was issued during workspace
resolution and/or loading of the Mufile. This leads to trying to
load an empty path and badness quickly ensues (crash).
* Issue an error if the Mufile wasn't found (this got lost apparently).
* Rename the ErrorMissingPackageName message to ErrorInvalidPackageName,
since missing names are now caught by our new fancy decoder that
understands required versus optional fields. We still need to guard
against illegal characters in the name, including the empty string "".
* During decoding, reject !src.IsValid elements. This represents the
zero value and should be treated equivalently to a missing field.
* Do not permit empty strings "" as Names or QNames. The old logic
accidentally permitted them because regexp.FindString("") == "", no
matter the regex!
* Move the TestDiagSink abstraction to a new pkg/util/testutil package,
allowing us to share this common code across multiple package tests.
* Fix up a few messages that needed tidying or to use Infof vs. Info.
The binder tests -- deleted in this -- are about to come back, however,
I am splitting up the changes, since this represents a passing fixed point.
