Wrong `if_same_then_else` lint error when having two different integer

[YouKnow-sys]

Summary

if we call a trait method on two different integer type in a if else condition and specify the types like 0_u8, 0u16 and... this lint will give us a error about both if and else are the same, when they're not...

Lint Name

if_same_then_else

Reproducer

I tried this code:

let test = if true { 0_u16.is_power_of_two() } else { 0_u8.is_power_of_two() };

I saw this happen:

error: this `if` has identical blocks
  --> src.rs:44:28
   |
44 |         let test = if true { 0_u16.is_power_of_two() } else { 0_u8.is_power_of_two() };
   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
note: same as this
  --> src.rs:44:61
   |
44 |         let test = if true { 0_u16.is_power_of_two() } else { 0_u8.is_power_of_two() };
   |                                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^                                                                           

I didn't expected to see any lint error here because I'm calling this trait method on two different type.

Version

rustc 1.71.0 (8ede3aae2 2023-07-12)
binary: rustc
commit-hash: 8ede3aae28fe6e4d52b38157d7bfe0d3bceef225
commit-date: 2023-07-12
host: x86_64-pc-windows-msvc
release: 1.71.0
LLVM version: 16.0.5

Additional Labels

No response

[y21]

From a quick look, it seems like SpanlessEq's way of checking if two integer literal expressions are equal is wrong because it disregards the types.

rust-clippy/clippy_utils/src/hir_utils.rs

Lines 255 to 264 in 43577d5

	if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
	if let (Some(l), Some(r)) = (
	constant_simple(self.inner.cx, typeck_lhs, left),
	constant_simple(self.inner.cx, typeck_rhs, right),
	) {
	if l == r {
	return true;
	}
	}
	}

Looks like it folds 0_u8 and 0_u16 to the constant 0 and concludes that the expressions must be equal

[YouKnow-sys]

From a quick look, it seems like SpanlessEq's way of checking if two integer literal expressions are equal is wrong because it disregards the types.

rust-clippy/clippy_utils/src/hir_utils.rs

Lines 255 to 264 in 43577d5

	if let Some((typeck_lhs, typeck_rhs)) = self.inner.maybe_typeck_results {
	if let (Some(l), Some(r)) = (
	constant_simple(self.inner.cx, typeck_lhs, left),
	constant_simple(self.inner.cx, typeck_rhs, right),
	) {
	if l == r {
	return true;
	}
	}
	}

Looks like it folds 0_u8 and 0_u16 to the constant 0 and concludes that the expressions must be equal

Well that only make sense if we are returning just a single integer literal (and even in that case returning different type from each arm is a error)
So by default it should check the type as well
Thanks for finding the problem