fix: #6558, only skip removing self if they are stacked like self::self

Author: MarcusGrass

src/imports.rs

@@ -557,9 +557,25 @@ impl UseTree {
                 self.path = vec![];
                 return self;
             }
+            UseSegmentKind::Slf(None) if self.path.is_empty() && self.visibility.is_some() => {
+                self.path = vec![];
+                return self;
+            }
             _ => (),
         }
 
+        // Normalise foo::self -> foo.
+        if let UseSegmentKind::Slf(None) = last.kind {
+            if let Some(second_last) = self.path.pop() {
+                if matches!(second_last.kind, UseSegmentKind::Slf(_)) {
+                    self.path.push(second_last);
+                } else {
+                    self.path.push(second_last);
+                    return self;
+                }
+            }
+        }
+
         // Normalise foo::self as bar -> foo as bar.
         if let UseSegmentKind::Slf(_) = last.kind {
             if let Some(UseSegment {

tests/source/imports/imports.rs

@@ -23,10 +23,8 @@ pub use rustc_ast::ast::{Expr_, Expr, ExprAssign, ExprCall, ExprMethodCall, Expr
 
 use rustc_ast::some::{};
 
-// compilation error that will (and should) be ignored by rustfmt #6558
 use self;
 use std::io::{self};
-// compilation error that will (and should) be ignored by rustfmt #6558
 use std::io::self;
 
 mod Foo {

tests/source/imports/imports_granularity_default-with-dups.rs

@@ -1,7 +1,6 @@
 use crate::lexer;
 use crate::lexer::tokens::TokenData;
 use crate::lexer::{tokens::TokenData};
-// compilation error that will (and should) be ignored by rustfmt #6558
 use crate::lexer::self;
 use crate::lexer::{self};
 use crate::lexer::{self, tokens::TokenData};

tests/source/issue_6558.rs

@@ -1,4 +1,4 @@
-// Removing `self` breaks idempotence, leaving it causes a compilation error
+// Removing `self::self` breaks idempotence, leaving it causes a compilation error
 // which the user should be made aware of #6558
 use self;
 use self::self;

tests/target/imports/imports.rs

@@ -27,11 +27,8 @@ use rustc_ast::{self};
 use Foo::{Bar, Baz};
 use {Bar /* comment */, /* Pre-comment! */ Foo};
 
-// compilation error that will (and should) be ignored by rustfmt #6558
-use self;
+use std::io;
 use std::io::{self};
-// compilation error that will (and should) be ignored by rustfmt #6558
-use std::io::self;
 
 mod Foo {
     pub use rustc_ast::ast::{

tests/target/imports/imports_granularity_default-with-dups.rs

@@ -1,7 +1,6 @@
 use crate::lexer;
+use crate::lexer;
 use crate::lexer::tokens::TokenData;
 use crate::lexer::tokens::TokenData;
-// compilation error that will (and should) be ignored by rustfmt #6558
-use crate::lexer::self;
 use crate::lexer::{self};
 use crate::lexer::{self, tokens::TokenData};

tests/target/issue_6558.rs

@@ -1,5 +1,4 @@
-// Removing `self` breaks idempotence, leaving it causes a compilation error
+// Removing `self::self` breaks idempotence, leaving it causes a compilation error
 // which the user should be made aware of #6558
-use self;
 use self::self;
 use self::self::self;