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https://github.com/rust-lang/rust-clippy
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Add a lint about suspiciously formatted else if
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810de56079
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4 changed files with 158 additions and 2 deletions
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@ -113,6 +113,7 @@ name
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[string_lit_as_bytes](https://github.com/Manishearth/rust-clippy/wiki#string_lit_as_bytes) | warn | calling `as_bytes` on a string literal; suggests using a byte string literal instead
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[string_to_string](https://github.com/Manishearth/rust-clippy/wiki#string_to_string) | warn | calling `String::to_string` which is inefficient
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[suspicious_assignment_formatting](https://github.com/Manishearth/rust-clippy/wiki#suspicious_assignment_formatting) | warn | suspicious formatting of `*=`, `-=` or `!=`
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[suspicious_else_formatting](https://github.com/Manishearth/rust-clippy/wiki#suspicious_else_formatting) | warn | suspicious formatting of `else if`
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[temporary_assignment](https://github.com/Manishearth/rust-clippy/wiki#temporary_assignment) | warn | assignments to temporaries
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[toplevel_ref_arg](https://github.com/Manishearth/rust-clippy/wiki#toplevel_ref_arg) | warn | An entire binding was declared as `ref`, in a function argument (`fn foo(ref x: Bar)`), or a `let` statement (`let ref x = foo()`). In such cases, it is preferred to take references with `&`.
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[trivial_regex](https://github.com/Manishearth/rust-clippy/wiki#trivial_regex) | warn | finds trivial regular expressions in `Regex::new(_)` invocations
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@ -6,7 +6,7 @@ use syntax::ptr::P;
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/// **What it does:** This lint looks for use of the non-existent `=*`, `=!` and `=-` operators.
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///
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/// **Why is this bad?** This either a typo of `*=`, `!=` or `-=` or confusing.
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/// **Why is this bad?** This is either a typo of `*=`, `!=` or `-=` or confusing.
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///
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/// **Known problems:** None.
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///
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@ -20,18 +20,65 @@ declare_lint! {
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"suspicious formatting of `*=`, `-=` or `!=`"
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}
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/// **What it does:** This lint checks for formatting of `else if`. It lints if the `else` and `if`
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/// are not on the same line or the `else` seems to be missing.
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///
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/// **Why is this bad?** This is probably some refactoring remnant, even if the code is correct, it
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/// might look confusing.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust,ignore
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/// if foo {
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/// } if bar { // looks like an `else` is missing here
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/// }
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///
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/// if foo {
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/// } else
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///
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/// if bar { // this is the `else` block of the previous `if`, but should it be?
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/// }
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/// ```
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declare_lint! {
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pub SUSPICIOUS_ELSE_FORMATTING,
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Warn,
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"suspicious formatting of `else if`"
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}
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#[derive(Copy,Clone)]
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pub struct Formatting;
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impl LintPass for Formatting {
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fn get_lints(&self) -> LintArray {
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lint_array![SUSPICIOUS_ASSIGNMENT_FORMATTING]
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lint_array![SUSPICIOUS_ASSIGNMENT_FORMATTING, SUSPICIOUS_ELSE_FORMATTING]
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}
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}
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impl EarlyLintPass for Formatting {
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fn check_block(&mut self, cx: &EarlyContext, block: &ast::Block) {
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for w in block.stmts.windows(2) {
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match (&w[0].node, &w[1].node) {
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(&ast::StmtKind::Expr(ref first, _), &ast::StmtKind::Expr(ref second, _)) |
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(&ast::StmtKind::Expr(ref first, _), &ast::StmtKind::Semi(ref second, _)) => {
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check_consecutive_ifs(cx, first, second);
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}
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_ => (),
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}
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}
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if let Some(ref expr) = block.expr {
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if let Some(ref stmt) = block.stmts.iter().last() {
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if let ast::StmtKind::Expr(ref first, _) = stmt.node {
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check_consecutive_ifs(cx, first, expr);
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}
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}
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}
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}
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fn check_expr(&mut self, cx: &EarlyContext, expr: &ast::Expr) {
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check_assign(cx, expr);
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check_else_if(cx, expr);
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}
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}
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@ -64,3 +111,62 @@ fn check_unop(expr: &ast::Expr) -> Option<(&P<ast::Expr>, &'static str)> {
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_ => None,
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}
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}
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/// Implementation of the SUSPICIOUS_ELSE_FORMATTING lint for weird `else if`.
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fn check_else_if(cx: &EarlyContext, expr: &ast::Expr) {
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if let Some((then, &Some(ref else_))) = unsugar_if(expr) {
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if unsugar_if(else_).is_some() &&
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!differing_macro_contexts(then.span, else_.span) &&
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!in_macro(cx, then.span) {
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// this will be a span from the closing ‘}’ of the “then” block (excluding) to the
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// “if” of the “else if” block (excluding)
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let else_span = mk_sp(then.span.hi, else_.span.lo);
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// the snippet should look like " else \n " with maybe comments anywhere
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// it’s bad when there is a ‘\n’ after the “else”
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if let Some(else_snippet) = snippet_opt(cx, else_span) {
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let else_pos = else_snippet.find("else").expect("there must be a `else` here");
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if else_snippet[else_pos..].contains('\n') {
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span_note_and_lint(cx,
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SUSPICIOUS_ELSE_FORMATTING,
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else_span,
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"this is an `else if` but the formatting might hide it",
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else_span,
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"to remove this lint, remove the `else` or remove the new line between `else` and `if`");
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}
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}
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}
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}
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}
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/// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for consecutive ifs.
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fn check_consecutive_ifs(cx: &EarlyContext, first: &ast::Expr, second: &ast::Expr) {
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if !differing_macro_contexts(first.span, second.span) &&
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!in_macro(cx, first.span) &&
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unsugar_if(first).is_some() &&
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unsugar_if(second).is_some() {
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// where the else would be
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let else_span = mk_sp(first.span.hi, second.span.lo);
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if let Some(else_snippet) = snippet_opt(cx, else_span) {
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if !else_snippet.contains('\n') {
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span_note_and_lint(cx,
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SUSPICIOUS_ELSE_FORMATTING,
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else_span,
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"this looks like an `else if` but the `else` is missing",
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else_span,
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"to remove this lint, add the missing `else` or add a new line before the second `if`");
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}
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}
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}
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}
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/// Match `if` or `else if` expressions and return the `then` and `else` block.
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fn unsugar_if(expr: &ast::Expr) -> Option<(&P<ast::Block>, &Option<P<ast::Expr>>)>{
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match expr.node {
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ast::ExprKind::If(_, ref then, ref else_) |
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ast::ExprKind::IfLet(_, _, ref then, ref else_) => Some((then, else_)),
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_ => None,
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}
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}
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@ -215,6 +215,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
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eta_reduction::REDUNDANT_CLOSURE,
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format::USELESS_FORMAT,
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formatting::SUSPICIOUS_ASSIGNMENT_FORMATTING,
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formatting::SUSPICIOUS_ELSE_FORMATTING,
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identity_op::IDENTITY_OP,
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items_after_statements::ITEMS_AFTER_STATEMENTS,
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len_zero::LEN_WITHOUT_IS_EMPTY,
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@ -6,7 +6,55 @@
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#![allow(unused_assignments)]
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#![allow(if_same_then_else)]
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fn foo() -> bool { true }
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fn main() {
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// weird `else if` formatting:
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if foo() {
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} if foo() { //~ERROR this looks like an `else if` but the `else` is missing
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}
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let _ = {
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if foo() {
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} if foo() { //~ERROR this looks like an `else if` but the `else` is missing
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}
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else {
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}
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};
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if foo() {
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} else //~ERROR this is an `else if` but the formatting might hide it
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if foo() { // the span of the above error should continue here
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}
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if foo() {
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} //~ERROR this is an `else if` but the formatting might hide it
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else
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if foo() { // the span of the above error should continue here
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}
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// those are ok:
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if foo() {
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}
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if foo() {
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}
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if foo() {
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} else if foo() {
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}
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if foo() {
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}
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else if foo() {
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}
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if foo() {
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}
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else if
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foo() {}
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// weird op_eq formatting:
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let mut a = 42;
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a =- 35;
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