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fix(toolset): handle underflow in version_sub function #6389

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Merged
jdx merged 1 commit into from
Sep 23, 2025
Merged

fix(toolset): handle underflow in version_sub function #6389

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3 changes: 3 additions & 0 deletions e2e/plugins/test_version_range
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Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,6 @@ assert "mise current tiny" "2.1.0"

mise local tiny@sub-0.1:3.1
assert "mise current tiny" "3.0.1"

mise local tiny@sub-0.0.1:3.0.0
assert "mise current tiny" "2.1.0"
32 changes: 30 additions & 2 deletions src/toolset/tool_request.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -303,15 +303,31 @@ impl ToolRequest {
/// subtracts sub from orig and removes suffix
/// e.g. version_sub("18.2.3", "2") -> "16"
/// e.g. version_sub("18.2.3", "0.1") -> "18.1"
/// e.g. version_sub("2.79.0", "0.0.1") -> "2.78" (underflow, returns prefix)
pub fn version_sub(orig: &str, sub: &str) -> String {
let mut orig = Version::new(orig).unwrap();
let sub = Version::new(sub).unwrap();
while orig.chunks.0.len() > sub.chunks.0.len() {
orig.chunks.0.pop();
}
for (i, orig_chunk) in orig.clone().chunks.0.iter().enumerate() {
for i in 0..orig.chunks.0.len() {
let m = sub.nth(i).unwrap();
orig.chunks.0[i] = Chunk::Numeric(orig_chunk.single_digit().unwrap() - m);
let orig_val = orig.chunks.0[i].single_digit().unwrap();

if orig_val < m {
// Handle underflow with borrowing from higher digits
for j in (0..i).rev() {
let prev_val = orig.chunks.0[j].single_digit().unwrap();
if prev_val > 0 {
orig.chunks.0[j] = Chunk::Numeric(prev_val - 1);
orig.chunks.0.truncate(j + 1);
return orig.to_string();
}
}
return "0".to_string();
Comment on lines +319 to +327

Copilot AI Sep 23, 2025

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The borrowing logic is incomplete. When a digit at position j has value 0, the algorithm should continue borrowing from higher digits (j-1, j-2, etc.) and set intermediate digits to their maximum borrowable value. Currently, it skips over zero digits without proper carry propagation, which could lead to incorrect results in cases like version_sub('1.0.0.1', '0.0.0.2').

Suggested change
for j in (0..i).rev() {
let prev_val = orig.chunks.0[j].single_digit().unwrap();
if prev_val > 0 {
orig.chunks.0[j] = Chunk::Numeric(prev_val - 1);
orig.chunks.0.truncate(j + 1);
return orig.to_string();
}
}
return "0".to_string();
// Propagate borrow through zeros and set intermediate digits to max value
let mut borrowed = false;
for j in (0..i).rev() {
let prev_val = orig.chunks.0[j].single_digit().unwrap();
if prev_val > 0 {
// Decrement the digit we borrow from
orig.chunks.0[j] = Chunk::Numeric(prev_val - 1);
// Set all digits between j+1 and i-1 to max value (9)
for k in (j+1)..i {
orig.chunks.0[k] = Chunk::Numeric(9);
}
borrowed = true;
break;
}
}
if !borrowed {
return "0".to_string();
}

Copilot uses AI. Check for mistakes.

@koh-sh koh-sh Sep 23, 2025

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The current implementation is actually correct. The algorithm properly handles the case you
mentioned:

For version_sub('1.0.0.1', '0.0.0.2'):

  1. Underflow occurs at position 3 (1 < 2)
  2. Loop searches backwards: j=2 (value=0, skip), j=1 (value=0, skip), j=0 (value=1, borrow)
  3. Borrows from position 0: decrements to 0, truncates to position 1
  4. Returns "0"

This behavior is intentional. Returning "0" allows the version resolution system to find the latest
available version within major version 0 (e.g., 0.9.x series), which is the expected behavior when
the subtraction would result in a negative version. This maintains consistency with mise's version
resolution logic where "0" acts as a fallback to resolve the latest version in the 0.x range.

If maintainers prefer different handling for such edge cases, I'm happy to adjust the implementation
accordingly.

}

orig.chunks.0[i] = Chunk::Numeric(orig_val - m);
}
orig.to_string()
}
Expand All @@ -332,5 +348,17 @@ mod tests {
fn test_version_sub() {
assert_str_eq!(version_sub("18.2.3", "2"), "16");
assert_str_eq!(version_sub("18.2.3", "0.1"), "18.1");
assert_str_eq!(version_sub("18.2.3", "0.0.1"), "18.2.2");
}

#[test]
fn test_version_sub_underflow() {
// Test cases that would cause underflow return prefix for higher digit
assert_str_eq!(version_sub("2.0.0", "0.0.1"), "1");
assert_str_eq!(version_sub("2.79.0", "0.0.1"), "2.78");
assert_str_eq!(version_sub("1.0.0", "0.1.0"), "0");
assert_str_eq!(version_sub("0.1.0", "1"), "0");
assert_str_eq!(version_sub("1.2.3", "0.2.4"), "0");
assert_str_eq!(version_sub("1.3.3", "0.2.4"), "1.0");
}
}
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