119 lines
4.7 KiB
Rust
119 lines
4.7 KiB
Rust
use rustc::lint::*;
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use std::collections::HashMap;
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use syntax::ast::*;
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use syntax::codemap::Span;
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use syntax::visit::FnKind;
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use utils::{span_lint, span_help_and_lint};
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/// **What it does:** This lint `Warn`s on struct field patterns bound to wildcards.
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///
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/// **Why is this bad?** Using `..` instead is shorter and leaves the focus on the fields that are actually bound.
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///
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/// **Known problems:** None.
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///
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/// **Example:** `let { a: _, b: ref b, c: _ } = ..`
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declare_lint!(pub UNNEEDED_FIELD_PATTERN, Warn,
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"Struct fields are bound to a wildcard instead of using `..`");
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/// **What it does:** This lint `Warn`s on function arguments having the similar names differing by an underscore
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///
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/// **Why is this bad?** It affects code readability
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///
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/// **Known problems:** None.
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///
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/// **Example:** `fn foo(a: i32, _a: i32) {}`
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declare_lint!(pub DUPLICATE_UNDERSCORE_ARGUMENT, Warn,
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"Function arguments having names which only differ by an underscore");
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#[derive(Copy, Clone)]
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pub struct MiscEarly;
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impl LintPass for MiscEarly {
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fn get_lints(&self) -> LintArray {
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lint_array!(UNNEEDED_FIELD_PATTERN, DUPLICATE_UNDERSCORE_ARGUMENT)
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}
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}
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impl EarlyLintPass for MiscEarly {
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fn check_pat(&mut self, cx: &EarlyContext, pat: &Pat) {
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if let PatStruct(ref npat, ref pfields, _) = pat.node {
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let mut wilds = 0;
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let type_name = match npat.segments.last() {
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Some(elem) => format!("{}", elem.identifier.name),
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None => String::new(),
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};
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for field in pfields {
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if field.node.pat.node == PatWild {
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wilds += 1;
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}
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}
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if !pfields.is_empty() && wilds == pfields.len() {
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span_help_and_lint(cx,
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UNNEEDED_FIELD_PATTERN,
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pat.span,
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"All the struct fields are matched to a wildcard pattern, consider using `..`.",
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&format!("Try with `{} {{ .. }}` instead", type_name));
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return;
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}
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if wilds > 0 {
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let mut normal = vec![];
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for field in pfields {
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if field.node.pat.node != PatWild {
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if let Ok(n) = cx.sess().codemap().span_to_snippet(field.span) {
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normal.push(n);
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}
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}
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}
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for field in pfields {
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if field.node.pat.node == PatWild {
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wilds -= 1;
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if wilds > 0 {
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span_lint(cx,
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UNNEEDED_FIELD_PATTERN,
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field.span,
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"You matched a field with a wildcard pattern. Consider using `..` instead");
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} else {
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span_help_and_lint(cx,
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UNNEEDED_FIELD_PATTERN,
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field.span,
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"You matched a field with a wildcard pattern. Consider using `..` \
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instead",
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&format!("Try with `{} {{ {}, .. }}`",
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type_name,
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normal[..].join(", ")));
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}
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}
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}
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}
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}
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}
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fn check_fn(&mut self, cx: &EarlyContext, _: FnKind, decl: &FnDecl, _: &Block, _: Span, _: NodeId) {
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let mut registered_names: HashMap<String, Span> = HashMap::new();
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for ref arg in &decl.inputs {
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if let PatIdent(_, sp_ident, None) = arg.pat.node {
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let arg_name = sp_ident.node.to_string();
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if arg_name.starts_with("_") {
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if let Some(correspondance) = registered_names.get(&arg_name[1..]) {
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span_lint(cx,
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DUPLICATE_UNDERSCORE_ARGUMENT,
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*correspondance,
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&format!("`{}` already exists, having another argument having almost the same \
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name makes code comprehension and documentation more difficult",
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arg_name[1..].to_owned()));
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}
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} else {
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registered_names.insert(arg_name, arg.pat.span);
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}
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}
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}
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}
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}
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