fix(find): -mindepth N -maxdepth M with N>M now matches nothing

[MsfPablo]

Fixes #778.

Problem

find <dir> -mindepth N -maxdepth M with N > M printed entries at the smaller depth instead of nothing. Repro (against current main, commit 1f19cdd):

$ mkdir -p depth-repro/1/2/3 && touch depth-repro/1/f1 depth-repro/f0
$ ./target/debug/find depth-repro -mindepth 2 -maxdepth 1
depth-repro/1
depth-repro/f0

GNU/BSD find print nothing here (no depth is simultaneously >= N and <= M):

$ find depth-repro -mindepth 2 -maxdepth 1   # BSD find, macOS
$                                            # (no output, exit 0)

Root cause

process_dir builds the walker with walkdir's min_depth/max_depth setters (src/find/mod.rs). Those setters silently clamp the contradiction — whichever is set last wins (walkdir src/lib.rs):

pub fn min_depth(mut self, depth: usize) -> Self {
    self.opts.min_depth = depth;
    if self.opts.min_depth > self.opts.max_depth {
        self.opts.min_depth = self.opts.max_depth;   // clamps min DOWN
    }
    self
}
pub fn max_depth(mut self, depth: usize) -> Self {
    self.opts.max_depth = depth;
    if self.opts.max_depth < self.opts.min_depth {
        self.opts.max_depth = self.opts.min_depth;   // clamps max UP
    }
    self
}

uutils calls .max_depth() first, then .min_depth(), so with max_depth=1, min_depth=2 the second call clamps min_depth down to 1 → the walk yields exactly the depth-1 entries.

Fix

Add an explicit guard at the top of process_dir that returns early (no output) when config.min_depth > config.max_depth, matching GNU/BSD find. The walkdir builder is left untouched.

// GNU/BSD find semantics: `-mindepth N -maxdepth M` with N > M matches no
// depth (none is simultaneously >= N and <= M), so the walk yields nothing.
// We must short-circuit here because walkdir's `min_depth`/`max_depth`
// setters silently clamp to resolve the contradiction (whichever is set last
// wins), which would instead surface entries at the smaller depth. See #778.
if config.min_depth > config.max_depth {
    return 0;
}

Verification

• cargo build --bin find — clean
• cargo test — 228 lib tests + integration suites pass (0 failures), including two new regression tests:
  • find_mindepth_greater_than_maxdepth (-mindepth 2 -maxdepth 1)
  • find_mindepth_greater_than_maxdepth_reversed_order (-maxdepth 1 -mindepth 2, both orderings must yield nothing)
• cargo fmt --check — clean
• cargo clippy --lib -- -D warnings — clean
• Manual repro now matches GNU/BSD: find depth-repro -mindepth 2 -maxdepth 1 → no output, exit 0

The existing find_mindepth / find_maxdepth / find_zero_maxdepth tests continue to pass unchanged.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.97%. Comparing base (1f19cdd) to head (bf2d93f).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #821      +/-   ##
==========================================
+ Coverage   91.93%   91.97%   +0.03%     
==========================================
  Files          35       35              
  Lines        7251     7286      +35     
  Branches      378      379       +1     
==========================================
+ Hits         6666     6701      +35     
  Misses        443      443              
  Partials      142      142              

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[codspeed-hq]

Merging this PR will not alter performance

✅ 20 untouched benchmarks

---

_{Comparing MsfPablo:fix-mindepth-greater-than-maxdepth (bf2d93f) with main (1f19cdd)}

[github-actions]

Commit bf2d93f has test result changes:

GNU findutils testsuite:

Test results comparison:
  Current:   TOTAL: 495 / PASSED: 417 / FAILED: 77 / SKIPPED: 1
  Reference: TOTAL: 495 / PASSED: 416 / FAILED: 78 / SKIPPED: 1

Changes from main branch:
  TOTAL: +0
  PASSED: +1
  FAILED: -1

Test improvements (1):
  + tests/find/refuse-noop

bfs testsuite:

Test results comparison:
  Current:   TOTAL: 315 / PASSED: 267 / FAILED: 42 / SKIPPED: 6
  Reference: TOTAL: 313 / PASSED: 267 / FAILED: 40 / SKIPPED: 6

Changes from main branch:
  TOTAL: +2
  PASSED: +0
  FAILED: +2

New test failures (2):
  - gnu/files0_from_ok
  - gnu/okdir_path_empty