fix collapsable_else_if when the inner if is in parens

Author: folkertdev

clippy_lints/src/collapsible_if.rs

@@ -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() {
@@ -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
@@ -298,6 +301,7 @@ fn span_extract_keyword(sm: &SourceMap, span: Span, keyword: &str) -> Option<Spa
         .next()
 }
 
+/// Peel the parentheses of off an `if` expression, e.g. `((if true {} else {}))`.
 fn peel_parens(sm: &SourceMap, mut span: Span) -> (Span, Span, Span) {
     use crate::rustc_span::Pos;
     use rustc_span::SpanData;
@@ -330,7 +334,5 @@ fn peel_parens(sm: &SourceMap, mut span: Span) -> (Span, Span, Span) {
         break;
     }
 
-    (start.with_hi(span.lo()),
-    span,
-    end.with_lo(span.hi()))
+    (start.with_hi(span.lo()), span, end.with_lo(span.hi()))
 }

tests/ui/collapsible_else_if.fixed

@@ -104,3 +104,13 @@ 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
+}

tests/ui/collapsible_else_if.rs

@@ -120,3 +120,15 @@ 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
+}

tests/ui/collapsible_else_if.stderr

@@ -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