Type of integer constant is ignored during folding of literal ops

[tserg]

Version Information

• vyper Version (output of vyper --version): 0.3.3
• OS: Linux
• Python Version (output of python --version): 3.8.5

What's your issue about?

Please include information like:

This contract compiles when it should throw a typechecking error.

a: constant(uint16) = 200

@external
def foo() -> int16:
	return a - 201

How can it be fixed?

Annotate the folded nodes with the original type information.

[tserg]

This also compiles, when it should not:

a: constant(uint16) = 200
b: constant(int248) = 100

@external
def foo() -> int16:
    return a - b

[tserg]

This also compiles, when it should not:

a: constant(uint8) = 255
b: constant(uint8) = 1

@external
def foo() -> uint8:
	return a + b

[UPDATE - this now throws an InvalidType as of 0.3.7]

[tserg]

Another example:

a: constant(int8) = 25
b: constant(uint8) = 38

@external
def foo() -> bool:
	return a < b

[trocher]

Might be redundant with your examples, but I got this one which is compiling:

a:constant(uint256)=1
b:constant(uint16)=a+0

Where this one does not:

a:constant(uint256)=1
b:constant(uint16)=a

[tserg]

Might be redundant with your examples, but I got this one which is compiling:

a:constant(uint256)=1
b:constant(uint16)=a+0

Where this one does not:

a:constant(uint256)=1
b:constant(uint16)=a

Cool! I will add both examples as test cases to #3201.

[ToonVanHove]

As a side note, this also causes some funky stuff when used as array index:

CONST: constant(int128) = 1

@external
def foo():
    array: uint256[10] = empty(uint256[10])
    a: int128 = 1

    array[a + CONST] = 20

When compiled this results in an AssertionError that is supposed to be unreachable.

[trocher]

As a side note, this also causes some funky stuff when used as array index:

CONST: constant(int128) = 1

@external
def foo():
    array: uint256[10] = empty(uint256[10])
    a: int128 = 1

    array[a + CONST] = 20

When compiled this results in an AssertionError that is supposed to be unreachable.

Interesting, for this one it seems that the typechecker allows a + CONST to be any integer types but when annotating a + CONST is given type uint256, it annotate a with its int128 type but visit_Constant annotates CONST with the uint256 obtained from the subscript's value type and does not care about its annotation obtained from folding..

[charles-cooper]

i think this was solved during recent refactoring of constant folding (see #3669 and #3719). @ToonVanHove @trocher please reopen if there are still any issues.