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Fix suggestion for collapsible_if and collapsible_else_if when the inner if is enclosed in parentheses #15304

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53 changes: 51 additions & 2 deletions clippy_lints/src/collapsible_if.rs
Original file line number Diff line number Diff line change
Expand Up @@ -136,6 +136,9 @@ impl CollapsibleIf {
return;
}

// Peel off any parentheses.
let (_, else_block_span, _) = peel_parens(cx.tcx.sess.source_map(), else_.span);

// Prevent "elseif"
// Check that the "else" is followed by whitespace
let requires_space = if let Some(c) = snippet(cx, up_to_else, "..").chars().last() {
Expand All @@ -152,7 +155,7 @@ impl CollapsibleIf {
if requires_space { " " } else { "" },
snippet_block_with_applicability(
cx,
else_.span,
else_block_span,
"..",
Some(else_block.span),
&mut applicability
Expand Down Expand Up @@ -187,7 +190,8 @@ impl CollapsibleIf {
.with_leading_whitespace(cx)
.into_span()
};
let inner_if = inner.span.split_at(2).0;
let (paren_start, inner_if_span, paren_end) = peel_parens(cx.tcx.sess.source_map(), inner.span);
let inner_if = inner_if_span.split_at(2).0;
let mut sugg = vec![
// Remove the outer then block `{`
(then_open_bracket, String::new()),
Expand All @@ -196,6 +200,17 @@ impl CollapsibleIf {
// Replace inner `if` by `&&`
(inner_if, String::from("&&")),
];

if !paren_start.is_empty() {
// Remove any leading parentheses '('
sugg.push((paren_start, String::new()));
}

if !paren_end.is_empty() {
// Remove any trailing parentheses ')'
sugg.push((paren_end, String::new()));
}

sugg.extend(parens_around(check));
sugg.extend(parens_around(check_inner));

Expand Down Expand Up @@ -285,3 +300,37 @@ fn span_extract_keyword(sm: &SourceMap, span: Span, keyword: &str) -> Option<Spa
})
.next()
}

/// Peel the parentheses from an `if` expression, e.g. `((if true {} else {}))`.
fn peel_parens(sm: &SourceMap, mut span: Span) -> (Span, Span, Span) {
use crate::rustc_span::Pos;

let start = span.shrink_to_lo();
let end = span.shrink_to_hi();

let snippet = sm.span_to_snippet(span).unwrap();
if let Some((trim_start, _, trim_end)) = peel_parens_str(&snippet) {
let mut data = span.data();
data.lo = data.lo + BytePos::from_usize(trim_start);
data.hi = data.hi - BytePos::from_usize(trim_end);
span = data.span();
}

(start.with_hi(span.lo()), span, end.with_lo(span.hi()))
}

fn peel_parens_str(snippet: &str) -> Option<(usize, &str, usize)> {
let trimmed = snippet.trim();
if !(trimmed.starts_with('(') && trimmed.ends_with(')')) {
return None;
}

let trim_start = (snippet.len() - snippet.trim_start().len()) + 1;
let trim_end = (snippet.len() - snippet.trim_end().len()) + 1;

let inner = snippet.get(trim_start..snippet.len() - trim_end)?;
Some(match peel_parens_str(inner) {
None => (trim_start, inner, trim_end),
Some((start, inner, end)) => (trim_start + start, inner, trim_end + end),
})
}
22 changes: 22 additions & 0 deletions tests/ui/collapsible_else_if.fixed
Original file line number Diff line number Diff line change
Expand Up @@ -104,3 +104,25 @@ fn issue14799() {
}
}
}

fn in_parens() {
let x = "hello";
let y = "world";

if x == "hello" {
print!("Hello ");
} else if y == "world" { println!("world") } else { println!("!") }
//~^^^ collapsible_else_if
}

fn in_brackets() {
let x = "hello";
let y = "world";

// There is no lint when the inner `if` is in a block.
if x == "hello" {
print!("Hello ");
} else {
{ if y == "world" { println!("world") } else { println!("!") } }
}
}
24 changes: 24 additions & 0 deletions tests/ui/collapsible_else_if.rs
Original file line number Diff line number Diff line change
Expand Up @@ -120,3 +120,27 @@ fn issue14799() {
}
}
}

fn in_parens() {
let x = "hello";
let y = "world";

if x == "hello" {
print!("Hello ");
} else {
(if y == "world" { println!("world") } else { println!("!") })
}
//~^^^ collapsible_else_if
}

fn in_brackets() {
let x = "hello";
let y = "world";

// There is no lint when the inner `if` is in a block.
if x == "hello" {
print!("Hello ");
} else {
{ if y == "world" { println!("world") } else { println!("!") } }
}
}
11 changes: 10 additions & 1 deletion tests/ui/collapsible_else_if.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -150,5 +150,14 @@ LL | | if false {}
LL | | }
| |_____^ help: collapse nested if block: `if false {}`

error: aborting due to 8 previous errors
error: this `else { if .. }` block can be collapsed
--> tests/ui/collapsible_else_if.rs:130:12
|
LL | } else {
| ____________^
LL | | (if y == "world" { println!("world") } else { println!("!") })
LL | | }
| |_____^ help: collapse nested if block: `if y == "world" { println!("world") } else { println!("!") }`

error: aborting due to 9 previous errors

18 changes: 18 additions & 0 deletions tests/ui/collapsible_if.fixed
Original file line number Diff line number Diff line change
Expand Up @@ -163,3 +163,21 @@ fn issue14799() {
if true {}
};
}

fn in_parens() {
if true
&& true {
println!("In parens, linted");
}
//~^^^^^ collapsible_if
}

fn in_brackets() {
if true {
{
if true {
println!("In brackets, not linted");
}
}
}
}
19 changes: 19 additions & 0 deletions tests/ui/collapsible_if.rs
Original file line number Diff line number Diff line change
Expand Up @@ -173,3 +173,22 @@ fn issue14799() {
if true {}
};
}

fn in_parens() {
if true {
(if true {
println!("In parens, linted");
})
}
//~^^^^^ collapsible_if
}

fn in_brackets() {
if true {
{
if true {
println!("In brackets, not linted");
}
}
}
}
20 changes: 19 additions & 1 deletion tests/ui/collapsible_if.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -190,5 +190,23 @@ LL | // This is a comment, do not collapse code to it
LL ~ ; 3
|

error: aborting due to 11 previous errors
error: this `if` statement can be collapsed
--> tests/ui/collapsible_if.rs:178:5
|
LL | / if true {
LL | | (if true {
LL | | println!("In parens, linted");
LL | | })
LL | | }
| |_____^
|
help: collapse nested if block
|
LL ~ if true
LL ~ && true {
LL | println!("In parens, linted");
LL ~ }
|

error: aborting due to 12 previous errors