harn-lint 0.10.122

Linter for the Harn programming language
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93

//! Post-walk handling for positional parameters that are not referenced.

use std::collections::HashSet;

use harn_parser::DiagnosticCode as Code;

use super::Linter;
use crate::diagnostic::{LintDiagnostic, LintSeverity};
use crate::fixes::replace_identifier_text_fix;

impl Linter<'_> {
    pub(super) fn finalize_unused_parameters(&mut self) {
        let removable_parameters: HashSet<_> = self
            .param_declarations
            .iter()
            .filter_map(|declaration| {
                let candidate = declaration.removable_pipeline.as_ref()?;
                (!self.references.contains(&declaration.name)
                    && !self.function_references.contains(&candidate.owner))
                .then(|| (candidate.owner.clone(), declaration.name.clone()))
            })
            .collect();

        for decl in &self.param_declarations {
            if (decl.name.starts_with('_') && decl.removable_pipeline.is_none())
                || self.references.contains(&decl.name)
            {
                continue;
            }
            if decl
                .removable_pipeline
                .as_ref()
                .is_some_and(|candidate| self.function_references.contains(&candidate.owner))
            {
                // The underscore already records that this retained caller-
                // owned positional slot is intentionally unused.
                continue;
            }
            let removable = decl
                .removable_pipeline
                .as_ref()
                .filter(|candidate| !self.function_references.contains(&candidate.owner));
            let (code, rule, suggestion, fix) = if let Some(candidate) = removable {
                let previous_will_be_removed =
                    candidate.previous_name.as_ref().is_some_and(|previous| {
                        removable_parameters.contains(&(candidate.owner.clone(), previous.clone()))
                    });
                let fix = if previous_will_be_removed {
                    candidate
                        .fix_after_removed_previous
                        .as_ref()
                        .unwrap_or(&candidate.fix)
                } else {
                    &candidate.fix
                };
                (
                    Code::LintUnusedPipelineInput,
                    "unused-pipeline-input",
                    "remove the unused test pipeline input; tests declare only the inputs they use"
                        .to_string(),
                    Some(fix.clone()),
                )
            } else {
                // Functions, closures, table-driven tests, fixtures, extended
                // pipelines, and referenced pipelines keep their positional
                // contract. A name prefix declares the slot unused.
                (
                    Code::LintUnusedParameter,
                    "unused-parameter",
                    format!(
                        "rename the parameter to `_{}` to preserve positional arity",
                        decl.name
                    ),
                    replace_identifier_text_fix(
                        self.source,
                        decl.span,
                        &decl.name,
                        &format!("_{}", decl.name),
                    ),
                )
            };
            self.diagnostics.push(LintDiagnostic {
                code,
                rule: rule.into(),
                message: format!("parameter `{}` is declared but never used", decl.name),
                span: decl.span,
                severity: LintSeverity::Warning,
                suggestion: Some(suggestion),
                fix,
            });
        }
    }
}