feat: protect external calls with `await` keyword

[charles-cooper]

What I did

implement https://github.com/vyperlang/vyper/issues/2856

(note: wait until after v0.3.4)

How I did it

How to verify it

tbd new tests note to self:

interface Foo:
    def foo(): nonpayable

@internal
def bar():
    pass

@external
def foo():
    await Foo(msg.sender).foo()

# bad:
#Foo(msg.sender).foo()
#await self.bar()
#await 1 + 1

Commit message

Commit message for the final, squashed PR. (Optional, but reviewers will appreciate it! Please see our commit message style guide for what we would ideally like to see in a commit message.)

Description for the changelog

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 97.16312% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 85.36%. Comparing base (45c6b6a) to head (b625c04).

Files	Patch %	Lines
vyper/codegen/expr.py	91.89%	1 Missing and 2 partials :warning:
vyper/ast/parse.py	92.30%	0 Missing and 1 partial :warning:

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2938      +/-   ##
==========================================
+ Coverage   85.23%   85.36%   +0.12%     
==========================================
  Files          92       92              
  Lines       13949    14031      +82     
  Branches     3130     3141      +11     
==========================================
+ Hits        11889    11977      +88     
+ Misses       1565     1560       -5     
+ Partials      495      494       -1     

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[fubuloubu]

breaking change, wait until 0.4.0

[charles-cooper]

for now i'm putting in the behavior as warning instead of an exception

[cyberthirst]

compiling

@external
def foo():
    s: String[2] = staticcall staticcall concat('a', 'b')
    return

yields:

  File "<unknown>", line 4
    s: String[2] = await      await      concat('a', 'b')
                              ^^^^^
SyntaxError: invalid syntax

The above exception was the direct cause of the following exception:

vyper.exceptions.SyntaxException: invalid syntax (<unknown>, line 4)

  line 4:31 
       3 def foo():
  ---> 4     s: String[2] = staticcall staticcall concat('a', 'b')
  --------------------------------------^
       5     return

see: s: String[2] = await await concat('a', 'b') also: File "<unknown>", line 4

[cyberthirst]

I assume this is the type of err that the description is alluding to:

interface I:
    def foo() -> uint256: view
    def bar(a: uint256): payable

event E:
    a: uint256

@external
@payable
def foo(_target: address) -> uint256:
    log E(staticcall I(_target).foo())
    return 1

yields:

    IndexError: list index out of rang

[cyberthirst]

compiling:

d: DynArray[uint256, 10]

interface I:
    def foo() -> DynArray[uint256, 10]: view


@external
def bar(t: address) -> uint256:
    for i: uint256 in staticcall I(t).foo():
        self.d.append(i)
    return 1

yields:

Error compiling: tests/custom/test5.vy
AssertionError: non-unique symbols {'I(t).foo()2'}

[cyberthirst]

compiling:

d: DynArray[uint256, 10]

interface I:
    def foo() -> DynArray[uint256, 10]: view
    def bar() -> uint256: payable


@external
def bar(t: address) -> uint256:
    for i: uint256 in range(extcall I(t).bar(), bound=10):
        self.d.append(i)
    return 1

yields:

Error compiling: tests/custom/test5.vy
vyper.exceptions.CodegenPanic: unhandled exception typechecker missed this, parse_ExtCall

  contract "tests/custom/test5.vy:10", function "bar", line 10:28 
        9 def bar(t: address) -> uint256:
  ---> 10     for i: uint256 in range(extcall I(t).bar(), bound=10):
  ------------------------------------^
       11         self.d.append(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

[cyberthirst]

compiling:

d: DynArray[uint256, 10]

interface I:
    def foo() -> DynArray[uint256, 10]: view


@external
def bar(t: address) -> uint256:
    for i: uint256 in staticcall I(t).foo():
        self.d.append(i)
    return 1

yields:

Error compiling: tests/custom/test5.vy
AssertionError: non-unique symbols {'I(t).foo()2'}

related:

interface I:
        def ohfak() -> decimal: view

@external
def bar(t: address):
    k: decimal = sqrt(staticcall I(t).ohfak())
    return

yields:

Error compiling: tests/custom/test4.vy
AssertionError: non-unique symbols {'I(t).ohfak()18'}

[charles-cooper]

see: s: String[2] = await await concat('a', 'b') also: File "<unknown>", line 4

seems unrelated -- there's a raise SyntaxException(...) from e in vyper/ast/parse.py; we could remove the from e

[charles-cooper]

compiling:

d: DynArray[uint256, 10]

interface I:
    def foo() -> DynArray[uint256, 10]: view
    def bar() -> uint256: payable


@external
def bar(t: address) -> uint256:
    for i: uint256 in range(extcall I(t).bar(), bound=10):
        self.d.append(i)
    return 1

yields:

Error compiling: tests/custom/test5.vy
vyper.exceptions.CodegenPanic: unhandled exception typechecker missed this, parse_ExtCall

  contract "tests/custom/test5.vy:10", function "bar", line 10:28 
        9 def bar(t: address) -> uint256:
  ---> 10     for i: uint256 in range(extcall I(t).bar(), bound=10):
  ------------------------------------^
       11         self.d.append(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

this is a bug on master too, not a regression in this PR

[charles-cooper]

the non-unique symbol panics are related to known bugs i think, not regressions