[pylint] Handle empty comments after line continuation (PLR2044) (#19405)

fixes #19326

Author: soundsonacid

crates/ruff_linter/resources/test/fixtures/pylint/empty_comment_line_continuation.py

@@ -0,0 +1,5 @@
+#
+x = 0 \
+#
++1
+print(x)

crates/ruff_linter/src/checkers/tokens.rs

@@ -58,7 +58,7 @@ pub(crate) fn check_tokens(
     }
 
     if context.is_rule_enabled(Rule::EmptyComment) {
-        pylint::rules::empty_comments(context, comment_ranges, locator);
+        pylint::rules::empty_comments(context, comment_ranges, locator, indexer);
     }
 
     if context.is_rule_enabled(Rule::AmbiguousUnicodeCharacterComment) {

crates/ruff_linter/src/rules/pylint/mod.rs

@@ -48,6 +48,7 @@ mod tests {
     #[test_case(Rule::ComparisonWithItself, Path::new("comparison_with_itself.py"))]
     #[test_case(Rule::EqWithoutHash, Path::new("eq_without_hash.py"))]
     #[test_case(Rule::EmptyComment, Path::new("empty_comment.py"))]
+    #[test_case(Rule::EmptyComment, Path::new("empty_comment_line_continuation.py"))]
     #[test_case(Rule::ManualFromImport, Path::new("import_aliasing.py"))]
     #[test_case(Rule::IfStmtMinMax, Path::new("if_stmt_min_max.py"))]
     #[test_case(Rule::SingleStringSlots, Path::new("single_string_slots.py"))]

crates/ruff_linter/src/rules/pylint/rules/empty_comment.rs

@@ -1,4 +1,5 @@
 use ruff_macros::{ViolationMetadata, derive_message_formats};
+use ruff_python_index::Indexer;
 use ruff_python_trivia::{CommentRanges, is_python_whitespace};
 use ruff_source_file::LineRanges;
 use ruff_text_size::{TextRange, TextSize};
@@ -49,6 +50,7 @@ pub(crate) fn empty_comments(
     context: &LintContext,
     comment_ranges: &CommentRanges,
     locator: &Locator,
+    indexer: &Indexer,
 ) {
     let block_comments = comment_ranges.block_comments(locator.contents());
 
@@ -59,12 +61,12 @@ pub(crate) fn empty_comments(
         }
 
         // If the line contains an empty comment, add a diagnostic.
-        empty_comment(context, range, locator);
+        empty_comment(context, range, locator, indexer);
     }
 }
 
 /// Return a [`Diagnostic`] if the comment at the given [`TextRange`] is empty.
-fn empty_comment(context: &LintContext, range: TextRange, locator: &Locator) {
+fn empty_comment(context: &LintContext, range: TextRange, locator: &Locator, indexer: &Indexer) {
     // Check: is the comment empty?
     if !locator
         .slice(range)
@@ -95,12 +97,20 @@ fn empty_comment(context: &LintContext, range: TextRange, locator: &Locator) {
             }
         });
 
+    // If there is no character preceding the comment, this comment must be on its own physical line.
+    // If there is a line preceding the empty comment's line, check if it ends in a line continuation character. (`\`)
+    let is_on_same_logical_line = indexer
+        .preceded_by_continuations(first_hash_col, locator.contents())
+        .is_some();
+
     if let Some(mut diagnostic) = context
         .report_diagnostic_if_enabled(EmptyComment, TextRange::new(first_hash_col, line.end()))
     {
         diagnostic.set_fix(Fix::safe_edit(
             if let Some(deletion_start_col) = deletion_start_col {
                 Edit::deletion(line.start() + deletion_start_col, line.end())
+            } else if is_on_same_logical_line {
+                Edit::deletion(first_hash_col, line.end())
             } else {
                 Edit::range_deletion(locator.full_line_range(first_hash_col))
             },

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLR2044_empty_comment_line_continuation.py.snap

@@ -0,0 +1,36 @@
+---
+source: crates/ruff_linter/src/rules/pylint/mod.rs
+---
+empty_comment_line_continuation.py:1:1: PLR2044 [*] Line with empty comment
+  |
+1 | #
+  | ^ PLR2044
+2 | x = 0 \
+3 | #
+  |
+  = help: Delete the empty comment
+
+ℹ Safe fix
+1   |-#
+2 1 | x = 0 \
+3 2 | #
+4 3 | +1
+
+empty_comment_line_continuation.py:3:1: PLR2044 [*] Line with empty comment
+  |
+1 | #
+2 | x = 0 \
+3 | #
+  | ^ PLR2044
+4 | +1
+5 | print(x)
+  |
+  = help: Delete the empty comment
+
+ℹ Safe fix
+1 1 | #
+2 2 | x = 0 \
+3   |-#
+  3 |+
+4 4 | +1
+5 5 | print(x)