feat[lang]: add module.__at__() to cast to interface

[charles-cooper]

What I did

fixes #3943, #3959

How I did it

How to verify it

Commit message

add `module.__at__`, a new `MemberFunctionT`, which allows the user to
cast addresses to a module's interface.

additionally, fix a bug where interfaces defined inline could not
be exported. this is simultaneously fixed as a related bug because
previously, interfaces could come up in export analysis as `InterfaceT`
or `TYPE_T` depending on their provenance. this commit fixes the bug by
making them `TYPE_T` in both imported and inlined provenance.

this also allows `module.__interface__` to be used in export position
by adding it to `ModuleT`'s members. note this has an unwanted side
effect of allowing `module.__interface__` in call position; in other
words, `module.__interface__(<address>)` has the same behavior as
`module.__at__(<address>)` when use as an expression. this can be
addressed in a later refactor.

refactor:
- wrap interfaces in `TYPE_T`
- streamline an `isinstance(t, (VyperType, TYPE_T))` check. TYPE_T` now
  inherits from `VyperType`, so it doesn't need to be listed separately

Description for the changelog

Cute Animal Picture

[cyberthirst]

we allow for exporting a module with no external functions - i think we should raise in such case:

# main.vy
import lib1

def f(x: Bytes[32*5]) -> uint256:
     k: uint256 = lib1.foo()
     return k


exports: lib1.__interface__

# lib1.vy
@internal
def foo() -> uint256:
    return 1

[cyberthirst]

import lib1

uses: lib1

@deploy
def __init__():
    lib1.__interface__(self).__init__()


exports: lib1.__interface__

#lib1.vy
k: uint256

@external
def bar():
    pass

@deploy
def __init__():
    self.k = 10

AttributeError: 'NoneType' object has no attribute 'module_t'

[cyberthirst]

__interface__ can be used in "weird positions:

main.vy
import lib1

#uses: lib1

@deploy
def __init__():
    log lib1.__interface__.Foo(1)
    s: lib1.Structt = lib1.__interface__.Structt(i=1)


exports: lib1.__interface__

#lib1.vy
event Foo:
    i: uint256

struct Structt:
    i: uint256

k: uint256

@external
def bar():
    pass

@deploy
def __init__():
    self.k = 10

[cyberthirst]

should address #3943, right?

[cyberthirst]

with -f annotated_ast i get:

AttributeError: 'FunctionDef' object has no attribute 'node_id'

# main.vy
import lib1

@external
def foo() -> uint256:
    return staticcall lib1.__interface__(self).d()
# lib1.vy
d: public(uint256)

[fubuloubu]

would it be too much to ask for implicit cast of mod to mod.__interface__? For either v: Mod in argument (convert to Interface to use like v.method(...)) or extcall Mod(v).method(...)

.__interface__ is a little awkward to specify

[charles-cooper]

with -f annotated_ast i get:

AttributeError: 'FunctionDef' object has no attribute 'node_id'

# main.vy
import lib1

@external
def foo() -> uint256:
    return staticcall lib1.__interface__(self).d()
# lib1.vy
d: public(uint256)

on latest (9621397) we get:

vyper.exceptions.UnknownAttribute: tmp/lib1.vy has no member 'd'.

  contract "tmp/main.vy:6", function "foo", line 6:22 
       5 def foo() -> uint256:
  ---> 6     return staticcall lib1.__interface__(self).d()
  -----------------------------^
       7

[charles-cooper]

would it be too much to ask for implicit cast of mod to mod.__interface__? For either v: Mod in argument (convert to Interface to use like v.method(...)) or extcall Mod(v).method(...)

.__interface__ is a little awkward to specify

yes but it's a bit hairy. it will feel ambiguous once we add deploy Mod(...) syntax

[charles-cooper]

we allow for exporting a module with no external functions - i think we should raise in such case:

# main.vy
import lib1

def f(x: Bytes[32*5]) -> uint256:
     k: uint256 = lib1.foo()
     return k


exports: lib1.__interface__

# lib1.vy
@internal
def foo() -> uint256:
    return 1

24ac428

[charles-cooper]

should address #3943, right?

yes. updated the PR description

[codecov]

Codecov Report

Attention: Patch coverage is 32.50000% with 27 lines in your changes missing coverage. Please review.

Project coverage is 47.70%. Comparing base (b3ea663) to head (9bac423).
Report is 10 commits behind head on master.

Files with missing lines	Patch %	Lines
vyper/semantics/analysis/module.py	10.00%	9 Missing ⚠️
vyper/codegen/expr.py	20.00%	8 Missing ⚠️
vyper/semantics/types/module.py	54.54%	5 Missing ⚠️
vyper/compiler/output.py	0.00%	1 Missing and 1 partial ⚠️
vyper/semantics/analysis/utils.py	0.00%	0 Missing and 1 partial ⚠️
vyper/semantics/types/base.py	66.66%	1 Missing ⚠️
vyper/semantics/types/function.py	0.00%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (b3ea663) and HEAD (9bac423). Click for more details.

HEAD has 137 uploads less than BASE

Flag	BASE (b3ea663)	HEAD (9bac423)
	138	1

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4090       +/-   ##
===========================================
- Coverage   91.40%   47.70%   -43.71%     
===========================================
  Files         112      112               
  Lines       15927    16028      +101     
  Branches     2694     2699        +5     
===========================================
- Hits        14558     7646     -6912     
- Misses        935     7749     +6814     
- Partials      434      633      +199     

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---

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[cyberthirst]

# lib1.vy
def doo():
    pass

# main.vy
import lib1

i: public(lib1.__interface__)

@external
def boo():
    pass

exports: self.i

Error compiling: tests/custom/test.vy
AttributeError: 'NoneType' object has no attribute '_metadata'

During handling of the above exception, another exception occurred:

vyper.exceptions.CompilerPanic: unhandled exception 'NoneType' object has no attribute '_metadata'

  contract "tests/custom/test.vy:9", line 9:0 
       8
  ---> 9 exports: self.i
  -------^


This is an unhandled internal compiler error. Please create an issue on Github to notify the developers!
https://github.com/vyperlang/vyper/issues/new?template=bug.md