Merge #11061
11061: Support "move if to guard" for if else chains r=weirane a=weirane The idea is to first parse the if else chain into a vector of `(Condition, BlockExpr)`s until we reach an iflet branch, an else branch, or the end (the tail). Then add the match arms with guard for the vector, and add the tail with no if guard. Because the whole original match arm is replaced and the generated code doesn't have redundent commas, I removed redundent commas in some test cases. Closes #11033. Co-authored-by: Wang Ruochen <wrc@ruo-chen.wang>
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7409880a07
@ -1,7 +1,9 @@
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use syntax::{
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ast::{edit::AstNodeEdit, make, AstNode, BlockExpr, ElseBranch, Expr, IfExpr, MatchArm},
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NodeOrToken,
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SyntaxKind::{COMMA, WHITESPACE},
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ast::{
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edit::AstNodeEdit, make, AstNode, BlockExpr, Condition, ElseBranch, Expr, IfExpr, MatchArm,
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Pat,
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},
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SyntaxKind::WHITESPACE,
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};
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use crate::{AssistContext, AssistId, AssistKind, Assists};
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@ -115,73 +117,107 @@ pub(crate) fn move_arm_cond_to_match_guard(acc: &mut Assists, ctx: &AssistContex
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}
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})?;
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let replace_node = replace_node.unwrap_or_else(|| if_expr.syntax().clone());
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let cond = if_expr.condition()?;
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let then_block = if_expr.then_branch()?;
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// Not support moving if let to arm guard
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if cond.is_pattern_cond() {
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return None;
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}
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let buf = format!(" if {}", cond.syntax().text());
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let needs_dedent = replace_node != *if_expr.syntax();
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let (conds_blocks, tail) = parse_if_chain(if_expr)?;
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acc.add(
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AssistId("move_arm_cond_to_match_guard", AssistKind::RefactorRewrite),
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"Move condition to match guard",
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replace_node.text_range(),
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|edit| {
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let then_only_expr = then_block.statements().next().is_none();
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edit.delete(match_arm.syntax().text_range());
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// Dedent if if_expr is in a BlockExpr
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let dedent = if needs_dedent {
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cov_mark::hit!(move_guard_ifelse_in_block);
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1
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} else {
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cov_mark::hit!(move_guard_ifelse_else_block);
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0
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};
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let then_arm_end = match_arm.syntax().text_range().end();
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let indent_level = match_arm.indent_level();
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let spaces = " ".repeat(indent_level.0 as _);
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match &then_block.tail_expr() {
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Some(then_expr) if then_only_expr => {
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edit.replace(replace_node.text_range(), then_expr.syntax().text());
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// Insert comma for expression if there isn't one
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match match_arm.syntax().last_child_or_token() {
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Some(NodeOrToken::Token(t)) if t.kind() == COMMA => {}
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_ => {
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cov_mark::hit!(move_guard_if_add_comma);
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edit.insert(match_arm.syntax().text_range().end(), ",");
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}
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}
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let mut first = true;
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for (cond, block) in conds_blocks {
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if !first {
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edit.insert(then_arm_end, format!("\n{}", spaces));
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} else {
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first = false;
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}
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_ if replace_node != *if_expr.syntax() => {
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// Dedent because if_expr is in a BlockExpr
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let replace_with = then_block.dedent(1.into()).syntax().text();
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edit.replace(replace_node.text_range(), replace_with)
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}
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_ => edit.replace(replace_node.text_range(), then_block.syntax().text()),
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}
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edit.insert(match_pat.syntax().text_range().end(), buf);
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// If with only an else branch
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if let Some(ElseBranch::Block(else_block)) = if_expr.else_branch() {
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let then_arm_end = match_arm.syntax().text_range().end();
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let else_only_expr = else_block.statements().next().is_none();
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let indent_level = match_arm.indent_level();
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let spaces = " ".repeat(indent_level.0 as _);
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edit.insert(then_arm_end, format!("\n{}{} => ", spaces, match_pat));
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match &else_block.tail_expr() {
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Some(else_expr) if else_only_expr => {
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cov_mark::hit!(move_guard_ifelse_expr_only);
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edit.insert(then_arm_end, else_expr.syntax().text());
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let guard = format!("{} if {} => ", match_pat, cond.syntax().text());
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edit.insert(then_arm_end, guard);
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let only_expr = block.statements().next().is_none();
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match &block.tail_expr() {
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Some(then_expr) if only_expr => {
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edit.insert(then_arm_end, then_expr.syntax().text());
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edit.insert(then_arm_end, ",");
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}
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_ if replace_node != *if_expr.syntax() => {
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cov_mark::hit!(move_guard_ifelse_in_block);
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edit.insert(then_arm_end, else_block.dedent(1.into()).syntax().text());
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_ => {
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let to_insert = block.dedent(dedent.into()).syntax().text();
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edit.insert(then_arm_end, to_insert)
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}
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}
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}
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if let Some(e) = tail {
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cov_mark::hit!(move_guard_ifelse_else_tail);
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let guard = format!("\n{}{} => ", spaces, match_pat);
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edit.insert(then_arm_end, guard);
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let only_expr = e.statements().next().is_none();
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match &e.tail_expr() {
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Some(expr) if only_expr => {
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cov_mark::hit!(move_guard_ifelse_expr_only);
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edit.insert(then_arm_end, expr.syntax().text());
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edit.insert(then_arm_end, ",");
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}
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_ => {
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cov_mark::hit!(move_guard_ifelse_else_block);
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edit.insert(then_arm_end, else_block.syntax().text());
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let to_insert = e.dedent(dedent.into()).syntax().text();
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edit.insert(then_arm_end, to_insert)
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}
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}
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} else {
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// There's no else branch. Add a pattern without guard, unless the following match
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// arm is `_ => ...`
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cov_mark::hit!(move_guard_ifelse_notail);
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match match_arm.syntax().next_sibling().and_then(MatchArm::cast) {
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Some(next_arm)
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if matches!(next_arm.pat(), Some(Pat::WildcardPat(_)))
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&& next_arm.guard().is_none() =>
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{
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cov_mark::hit!(move_guard_ifelse_has_wildcard);
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}
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_ => edit.insert(then_arm_end, format!("\n{}{} => {{}}", spaces, match_pat)),
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}
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}
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},
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)
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}
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// Parses an if-else-if chain to get the conditons and the then branches until we encounter an else
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// branch or the end.
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fn parse_if_chain(if_expr: IfExpr) -> Option<(Vec<(Condition, BlockExpr)>, Option<BlockExpr>)> {
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let mut conds_blocks = Vec::new();
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let mut curr_if = if_expr;
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let tail = loop {
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let cond = curr_if.condition()?;
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// Not support moving if let to arm guard
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if cond.is_pattern_cond() {
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return None;
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}
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conds_blocks.push((cond, curr_if.then_branch()?));
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match curr_if.else_branch() {
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Some(ElseBranch::IfExpr(e)) => {
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curr_if = e;
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}
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Some(ElseBranch::Block(b)) => {
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break Some(b);
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}
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None => break None,
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}
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};
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Some((conds_blocks, tail))
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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@ -294,6 +330,7 @@ fn main() {
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#[test]
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fn move_arm_cond_in_block_to_match_guard_works() {
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cov_mark::check!(move_guard_ifelse_has_wildcard);
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check_assist(
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move_arm_cond_to_match_guard,
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r#"
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@ -319,9 +356,64 @@ fn main() {
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);
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}
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#[test]
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fn move_arm_cond_in_block_to_match_guard_no_wildcard_works() {
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cov_mark::check_count!(move_guard_ifelse_has_wildcard, 0);
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check_assist(
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move_arm_cond_to_match_guard,
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r#"
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fn main() {
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match 92 {
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x => {
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$0if x > 10 {
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false
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}
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}
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}
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}
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"#,
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r#"
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fn main() {
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match 92 {
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x if x > 10 => false,
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x => {}
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}
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}
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"#,
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);
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}
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#[test]
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fn move_arm_cond_in_block_to_match_guard_wildcard_guard_works() {
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cov_mark::check_count!(move_guard_ifelse_has_wildcard, 0);
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check_assist(
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move_arm_cond_to_match_guard,
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r#"
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fn main() {
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match 92 {
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x => {
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$0if x > 10 {
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false
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}
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}
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_ if x > 10 => true,
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}
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}
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"#,
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r#"
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fn main() {
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match 92 {
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x if x > 10 => false,
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x => {}
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_ if x > 10 => true,
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}
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}
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"#,
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);
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}
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#[test]
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fn move_arm_cond_in_block_to_match_guard_add_comma_works() {
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cov_mark::check!(move_guard_if_add_comma);
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check_assist(
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move_arm_cond_to_match_guard,
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r#"
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@ -377,7 +469,7 @@ fn main() {
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r#"
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fn main() {
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match 92 {
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x if x > 10 => { },
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x if x > 10 => { }
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_ => true
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}
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}
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@ -406,7 +498,7 @@ fn main() {
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x if x > 10 => {
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92;
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false
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},
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}
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_ => true
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}
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}
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@ -519,7 +611,7 @@ fn main() {
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r#"
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fn main() {
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match 92 {
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x if x > 10 => { },
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x if x > 10 => { }
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x => { }
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_ => true
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}
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@ -690,6 +782,177 @@ fn main() {
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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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#[test]
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fn move_arm_cond_to_match_guard_elseif() {
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check_assist(
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move_arm_cond_to_match_guard,
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r#"
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fn main() {
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match 92 {
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3 => true,
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x => if x > 10 {$0
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false
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} else if x > 5 {
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true
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} else if x > 4 {
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false
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} else {
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true
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},
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}
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}
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"#,
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r#"
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fn main() {
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match 92 {
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3 => true,
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x if x > 10 => false,
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x if x > 5 => true,
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x if x > 4 => false,
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x => true,
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}
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}
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"#,
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)
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}
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#[test]
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fn move_arm_cond_to_match_guard_elseif_in_block() {
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cov_mark::check!(move_guard_ifelse_in_block);
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check_assist(
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move_arm_cond_to_match_guard,
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r#"
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fn main() {
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match 92 {
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3 => true,
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x => {
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if x > 10 {$0
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false
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} else if x > 5 {
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true
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} else if x > 4 {
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false
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} else {
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true
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}
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}
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}
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}
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"#,
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r#"
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fn main() {
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match 92 {
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3 => true,
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x if x > 10 => false,
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x if x > 5 => true,
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x if x > 4 => false,
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x => true,
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}
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}
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"#,
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)
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}
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#[test]
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fn move_arm_cond_to_match_guard_elseif_chain() {
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cov_mark::check!(move_guard_ifelse_else_tail);
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check_assist(
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move_arm_cond_to_match_guard,
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r#"
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fn main() {
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match 92 {
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3 => 0,
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x => if x > 10 {$0
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1
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} else if x > 5 {
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2
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} else if x > 3 {
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42;
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3
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} else {
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4
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},
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}
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}
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"#,
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r#"
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fn main() {
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match 92 {
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3 => 0,
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x if x > 10 => 1,
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x if x > 5 => 2,
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x if x > 3 => {
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42;
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3
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}
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x => 4,
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}
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}
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"#,
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)
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}
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#[test]
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fn move_arm_cond_to_match_guard_elseif_iflet() {
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check_assist_not_applicable(
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move_arm_cond_to_match_guard,
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r#"
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fn main() {
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match 92 {
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3 => 0,
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x => if x > 10 {$0
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1
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} else if x > 5 {
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2
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} else if let 4 = 4 {
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42;
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3
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} else {
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4
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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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#[test]
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fn move_arm_cond_to_match_guard_elseif_notail() {
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cov_mark::check!(move_guard_ifelse_notail);
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check_assist(
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move_arm_cond_to_match_guard,
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r#"
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fn main() {
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match 92 {
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3 => 0,
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x => if x > 10 {$0
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1
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} else if x > 5 {
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2
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} else if x > 4 {
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42;
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3
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},
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}
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}
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"#,
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r#"
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fn main() {
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match 92 {
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3 => 0,
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x if x > 10 => 1,
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x if x > 5 => 2,
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x if x > 4 => {
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42;
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3
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}
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x => {}
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}
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}
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"#,
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)
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}
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