add Int::(unsafe)_to_char

[bobzhang]

• add Int::to_char safe API
• add Int::unsafe_to_char

[peter-jerry-ye-code-review]

The test 'Int::to_char - Invalid values' is duplicated

Category
Correctness
Code Snippet
test 'Int::to_char - Invalid values' appears twice in intrinsics_test.mbt
Recommendation
Remove one of the duplicate test blocks or rename them to be more specific about what they're testing
Reasoning
Having duplicate test names can cause confusion and makes it harder to reference specific tests. The two test blocks test different invalid cases, so they should have distinct names.

Missing documentation for unsafe_to_char and to_char functions

Category
Maintainability
Code Snippet
///|
pub fn Int::unsafe_to_char(self : Int) -> Char = "%char_from_int"

///|
pub fn Int::to_char(self : Int) -> Char?
Recommendation
Add detailed documentation explaining the valid range of inputs, the purpose of each function, and why/when to use the unsafe version
Reasoning
Functions dealing with character encoding and unsafe operations should be well-documented to prevent misuse and make the API more user-friendly. The documentation should explain the valid Unicode ranges and the risks of using unsafe_to_char.

Missing symbolic constants for Unicode range values

Category
Maintainability
Code Snippet
if self is (0..=0xD7FF) || self is (0xE000..=0x10FFFF)
Recommendation
Define named constants for these Unicode range boundaries:

const UNICODE_HIGH_SURROGATE_START : Int = 0xD800
const UNICODE_LOW_SURROGATE_END : Int = 0xDFFF
const UNICODE_MAX : Int = 0x10FFFF

Reasoning
Using magic numbers makes the code harder to maintain and understand. Named constants would make the code more readable and ensure consistency if these values need to be referenced elsewhere.

[coveralls]

Pull Request Test Coverage Report for Build 6449

Details

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 92.686%

---

Totals
Change from base Build 6448:	0.003%
Covered Lines:	6121
Relevant Lines:	6604

---

💛 - Coveralls

[bobzhang]

cc @peter-jerry-ye we will use x.(unsafe)_to_char to replace Char::from_int since the former provide a better auto-completion experience