Lints and suggestions for the Nix programming language
refactor(useless_has_attr): let-else and try-expression
+45
-39
+45
-39
lib/src/lints/useless_has_attr.rs
+45
-39
lib/src/lints/useless_has_attr.rs
···
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impl Rule for UselessHasAttr {
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fn validate(&self, node: &SyntaxElement, _sess: &SessionInfo) -> Option<Report> {
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if let NodeOrToken::Node(node) = node
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&& let Some(if_else_expr) = IfElse::cast(node.clone())
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&& let Some(condition_expr) = if_else_expr.condition()
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&& let Some(default_expr) = if_else_expr.else_body()
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&& let Some(cond_bin_expr) = BinOp::cast(condition_expr)
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&& let Some(BinOpKind::IsSet) = cond_bin_expr.operator()
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let NodeOrToken::Node(node) = node else {
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return None;
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};
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// set ? attr_path
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// ^^^--------------- lhs
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// ^^^^^^^^^^--- rhs
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&& let Some(set) = cond_bin_expr.lhs()
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&& let Some(attr_path) = cond_bin_expr.rhs()
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let if_else_expr = IfElse::cast(node.clone())?;
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let condition_expr = if_else_expr.condition()?;
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let default_expr = if_else_expr.else_body()?;
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let cond_bin_expr = BinOp::cast(condition_expr)?;
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let Some(BinOpKind::IsSet) = cond_bin_expr.operator() else {
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return None;
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};
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// check if body of the `if` expression is of the form `set.attr_path`
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&& let Some(body_expr) = if_else_expr.body()
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&& let Some(body_select_expr) = Select::cast(body_expr)
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&&let expected_body = make::select(&set, &attr_path)
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// set ? attr_path
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// ^^^--------------- lhs
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// ^^^^^^^^^^--- rhs
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let set = cond_bin_expr.lhs()?;
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let attr_path = cond_bin_expr.rhs()?;
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// text comparison will do for now
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&& body_select_expr.node().text() == expected_body.node().text()
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{
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let at = node.text_range();
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// `or` is tightly binding, we need to parenthesize non-literal exprs
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let default_with_parens = match default_expr.kind() {
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SyntaxKind::NODE_LIST
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| SyntaxKind::NODE_PAREN
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| SyntaxKind::NODE_STRING
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| SyntaxKind::NODE_ATTR_SET
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| SyntaxKind::NODE_IDENT
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| SyntaxKind::NODE_SELECT => default_expr,
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_ => make::parenthesize(&default_expr).node().clone(),
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};
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let replacement = make::or_default(&set, &attr_path, &default_with_parens)
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.node()
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.clone();
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let message = format!("Consider using `{replacement}` instead of this `if` expression");
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Some(
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self.report()
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.suggest(at, message, Suggestion::new(at, replacement)),
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)
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} else {
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None
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// check if body of the `if` expression is of the form `set.attr_path`
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let body_expr = if_else_expr.body()?;
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let body_select_expr = Select::cast(body_expr)?;
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let expected_body = make::select(&set, &attr_path);
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+
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// text comparison will do for now
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if body_select_expr.node().text() != expected_body.node().text() {
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return None;
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}
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+
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let at = node.text_range();
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+
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// `or` is tightly binding, we need to parenthesize non-literal exprs
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let default_with_parens = match default_expr.kind() {
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SyntaxKind::NODE_LIST
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| SyntaxKind::NODE_PAREN
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| SyntaxKind::NODE_STRING
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| SyntaxKind::NODE_ATTR_SET
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| SyntaxKind::NODE_IDENT
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| SyntaxKind::NODE_SELECT => default_expr,
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_ => make::parenthesize(&default_expr).node().clone(),
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};
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+
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let replacement = make::or_default(&set, &attr_path, &default_with_parens)
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.node()
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.clone();
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let message = format!("Consider using `{replacement}` instead of this `if` expression");
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Some(
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self.report()
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.suggest(at, message, Suggestion::new(at, replacement)),
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)
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}
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}