[flake8-use-pathlib] Catch redundant joins in PTH201 and avoid syntax errors (#15177)

## Summary

Resolves #10453, resolves #15165.

## Test Plan

`cargo nextest run` and `cargo insta test`.

crates/ruff_linter/resources/test/fixtures/flake8_use_pathlib/PTH201.py

@@ -1,15 +1,70 @@
 from pathlib import Path, PurePath
 from pathlib import Path as pth
 
+
 # match
 _ = Path(".")
 _ = pth(".")
 _ = PurePath(".")
 _ = Path("")
 
+Path('', )
+
+Path(
+    '',
+)
+
+Path(  # Comment before argument
+    '',
+)
+
+Path(
+    '',  # EOL comment
+)
+
+Path(
+    ''  # Comment in the middle of implicitly concatenated string
+    ".",
+)
+
+Path(
+    ''  # Comment before comma
+    ,
+)
+
+Path(
+    '',
+) / "bare"
+
+Path(  # Comment before argument
+    '',
+) / ("parenthesized")
+
+Path(
+    '',  # EOL comment
+) / ( ("double parenthesized"  )   )
+
+(  Path(
+    ''  # Comment in the middle of implicitly concatenated string
+    ".",
+) )/ (("parenthesized path call")
+      # Comment between closing parentheses
+)
+
+Path(
+    ''  # Comment before comma
+    ,
+) / "multiple" / (
+    "frag"  # Comment
+    'ment'
+)
+
+
 # no match
 _ = Path()
 print(".")
 Path("file.txt")
 Path(".", "folder")
 PurePath(".", "folder")
+
+Path()

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

@@ -983,7 +983,7 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
                 flake8_use_pathlib::rules::replaceable_by_pathlib(checker, call);
             }
             if checker.enabled(Rule::PathConstructorCurrentDirectory) {
-                flake8_use_pathlib::rules::path_constructor_current_directory(checker, expr, func);
+                flake8_use_pathlib::rules::path_constructor_current_directory(checker, call);
             }
             if checker.enabled(Rule::OsSepSplit) {
                 flake8_use_pathlib::rules::os_sep_split(checker, call);

crates/ruff_linter/src/rules/flake8_use_pathlib/rules/path_constructor_current_directory.rs

@@ -1,8 +1,15 @@
-use ruff_diagnostics::{AlwaysFixableViolation, Diagnostic, Edit, Fix};
+use std::ops::Range;
+
+use ruff_diagnostics::{AlwaysFixableViolation, Applicability, Diagnostic, Edit, Fix};
 use ruff_macros::{derive_message_formats, ViolationMetadata};
-use ruff_python_ast::{self as ast, Expr, ExprCall};
+use ruff_python_ast::parenthesize::parenthesized_range;
+use ruff_python_ast::{AstNode, Expr, ExprBinOp, ExprCall, Operator};
+use ruff_python_semantic::SemanticModel;
+use ruff_python_trivia::CommentRanges;
+use ruff_text_size::{Ranged, TextRange};
 
 use crate::checkers::ast::Checker;
+use crate::fix::edits::{remove_argument, Parentheses};
 
 /// ## What it does
 /// Checks for `pathlib.Path` objects that are initialized with the current
@@ -43,7 +50,17 @@ impl AlwaysFixableViolation for PathConstructorCurrentDirectory {
 }
 
 /// PTH201
-pub(crate) fn path_constructor_current_directory(checker: &mut Checker, expr: &Expr, func: &Expr) {
+pub(crate) fn path_constructor_current_directory(checker: &mut Checker, call: &ExprCall) {
+    let applicability = |range| {
+        if checker.comment_ranges().intersects(range) {
+            Applicability::Unsafe
+        } else {
+            Applicability::Safe
+        }
+    };
+
+    let (func, arguments) = (&call.func, &call.arguments);
+
     if !checker
         .semantic()
         .resolve_qualified_name(func)
@@ -54,21 +71,75 @@ pub(crate) fn path_constructor_current_directory(checker: &mut Checker, expr: &E
         return;
     }
 
-    let Expr::Call(ExprCall { arguments, .. }) = expr else {
-        return;
-    };
-
     if !arguments.keywords.is_empty() {
         return;
     }
 
-    let [Expr::StringLiteral(ast::ExprStringLiteral { value, range })] = &*arguments.args else {
+    let [Expr::StringLiteral(arg)] = &*arguments.args else {
         return;
     };
 
-    if matches!(value.to_str(), "" | ".") {
-        let mut diagnostic = Diagnostic::new(PathConstructorCurrentDirectory, *range);
-        diagnostic.set_fix(Fix::safe_edit(Edit::range_deletion(*range)));
-        checker.diagnostics.push(diagnostic);
+    if !matches!(arg.value.to_str(), "" | ".") {
+        return;
     }
+
+    let mut diagnostic = Diagnostic::new(PathConstructorCurrentDirectory, arg.range());
+
+    match parent_and_next_path_fragment_range(
+        checker.semantic(),
+        checker.comment_ranges(),
+        checker.source(),
+    ) {
+        Some((parent_range, next_fragment_range)) => {
+            let next_fragment_expr = checker.locator().slice(next_fragment_range);
+            let call_expr = checker.locator().slice(call.range());
+
+            let relative_argument_range: Range<usize> = {
+                let range = arg.range() - call.start();
+                range.start().into()..range.end().into()
+            };
+
+            let mut new_call_expr = call_expr.to_string();
+            new_call_expr.replace_range(relative_argument_range, next_fragment_expr);
+
+            let edit = Edit::range_replacement(new_call_expr, parent_range);
+
+            diagnostic.set_fix(Fix::applicable_edit(edit, applicability(parent_range)));
+        }
+        None => diagnostic.try_set_fix(|| {
+            let edit = remove_argument(arg, arguments, Parentheses::Preserve, checker.source())?;
+            Ok(Fix::applicable_edit(edit, applicability(call.range())))
+        }),
+    };
+
+    checker.diagnostics.push(diagnostic);
+}
+
+fn parent_and_next_path_fragment_range(
+    semantic: &SemanticModel,
+    comment_ranges: &CommentRanges,
+    source: &str,
+) -> Option<(TextRange, TextRange)> {
+    let parent = semantic.current_expression_parent()?;
+
+    let Expr::BinOp(parent @ ExprBinOp { op, right, .. }) = parent else {
+        return None;
+    };
+
+    let range = right.range();
+
+    if !matches!(op, Operator::Div) {
+        return None;
+    }
+
+    Some((
+        parent.range(),
+        parenthesized_range(
+            right.into(),
+            parent.as_any_node_ref(),
+            comment_ranges,
+            source,
+        )
+        .unwrap_or(range),
+    ))
 }

crates/ruff_linter/src/rules/flake8_use_pathlib/snapshots/ruff_linter__rules__flake8_use_pathlib__tests__PTH201_PTH201.py.snap

@@ -2,84 +2,329 @@
 source: crates/ruff_linter/src/rules/flake8_use_pathlib/mod.rs
 snapshot_kind: text
 ---
-PTH201.py:5:10: PTH201 [*] Do not pass the current directory explicitly to `Path`
+PTH201.py:6:10: PTH201 [*] Do not pass the current directory explicitly to `Path`
   |
-4 | # match
-5 | _ = Path(".")
+5 | # match
+6 | _ = Path(".")
   |          ^^^ PTH201
-6 | _ = pth(".")
-7 | _ = PurePath(".")
-  |
-  = help: Remove the current directory argument
-
-ℹ Safe fix
-2 2 | from pathlib import Path as pth
-3 3 | 
-4 4 | # match
-5   |-_ = Path(".")
-  5 |+_ = Path()
-6 6 | _ = pth(".")
-7 7 | _ = PurePath(".")
-8 8 | _ = Path("")
-
-PTH201.py:6:9: PTH201 [*] Do not pass the current directory explicitly to `Path`
-  |
-4 | # match
-5 | _ = Path(".")
-6 | _ = pth(".")
-  |         ^^^ PTH201
-7 | _ = PurePath(".")
-8 | _ = Path("")
+7 | _ = pth(".")
+8 | _ = PurePath(".")
   |
   = help: Remove the current directory argument
 
 ℹ Safe fix
 3 3 | 
-4 4 | # match
-5 5 | _ = Path(".")
-6   |-_ = pth(".")
-  6 |+_ = pth()
-7 7 | _ = PurePath(".")
-8 8 | _ = Path("")
-9 9 | 
+4 4 | 
+5 5 | # match
+6   |-_ = Path(".")
+  6 |+_ = Path()
+7 7 | _ = pth(".")
+8 8 | _ = PurePath(".")
+9 9 | _ = Path("")
 
-PTH201.py:7:14: PTH201 [*] Do not pass the current directory explicitly to `Path`
+PTH201.py:7:9: PTH201 [*] Do not pass the current directory explicitly to `Path`
   |
-5 | _ = Path(".")
-6 | _ = pth(".")
-7 | _ = PurePath(".")
+5 | # match
+6 | _ = Path(".")
+7 | _ = pth(".")
   |         ^^^ PTH201
-8 | _ = Path("")
+8 | _ = PurePath(".")
+9 | _ = Path("")
   |
   = help: Remove the current directory argument
 
 ℹ Safe fix
-4 4 | # match
-5 5 | _ = Path(".")
-6 6 | _ = pth(".")
-7   |-_ = PurePath(".")
-  7 |+_ = PurePath()
-8 8 | _ = Path("")
-9 9 | 
-10 10 | # no match
+4 4 | 
+5 5 | # match
+6 6 | _ = Path(".")
+7   |-_ = pth(".")
+  7 |+_ = pth()
+8 8 | _ = PurePath(".")
+9 9 | _ = Path("")
+10 10 | 
 
-PTH201.py:8:10: PTH201 [*] Do not pass the current directory explicitly to `Path`
+PTH201.py:8:14: PTH201 [*] Do not pass the current directory explicitly to `Path`
   |
- 6 | _ = pth(".")
- 7 | _ = PurePath(".")
- 8 | _ = Path("")
+6 | _ = Path(".")
+7 | _ = pth(".")
+8 | _ = PurePath(".")
+  |              ^^^ PTH201
+9 | _ = Path("")
+  |
+  = help: Remove the current directory argument
+
+ℹ Safe fix
+5 5 | # match
+6 6 | _ = Path(".")
+7 7 | _ = pth(".")
+8   |-_ = PurePath(".")
+  8 |+_ = PurePath()
+9 9 | _ = Path("")
+10 10 | 
+11 11 | Path('', )
+
+PTH201.py:9:10: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+ 7 | _ = pth(".")
+ 8 | _ = PurePath(".")
+ 9 | _ = Path("")
    |          ^^ PTH201
- 9 | 
-10 | # no match
+10 | 
+11 | Path('', )
    |
    = help: Remove the current directory argument
 
 ℹ Safe fix
-5 5 | _ = Path(".")
-6 6 | _ = pth(".")
-7 7 | _ = PurePath(".")
-8   |-_ = Path("")
-  8 |+_ = Path()
-9 9 | 
-10 10 | # no match
-11 11 | _ = Path()
+6  6  | _ = Path(".")
+7  7  | _ = pth(".")
+8  8  | _ = PurePath(".")
+9     |-_ = Path("")
+   9  |+_ = Path()
+10 10 | 
+11 11 | Path('', )
+12 12 | 
+
+PTH201.py:11:6: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+ 9 | _ = Path("")
+10 | 
+11 | Path('', )
+   |      ^^ PTH201
+12 | 
+13 | Path(
+   |
+   = help: Remove the current directory argument
+
+ℹ Safe fix
+8  8  | _ = PurePath(".")
+9  9  | _ = Path("")
+10 10 | 
+11    |-Path('', )
+   11 |+Path()
+12 12 | 
+13 13 | Path(
+14 14 |     '',
+
+PTH201.py:14:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+13 | Path(
+14 |     '',
+   |     ^^ PTH201
+15 | )
+   |
+   = help: Remove the current directory argument
+
+ℹ Safe fix
+10 10 | 
+11 11 | Path('', )
+12 12 | 
+13    |-Path(
+14    |-    '',
+15    |-)
+   13 |+Path()
+16 14 | 
+17 15 | Path(  # Comment before argument
+18 16 |     '',
+
+PTH201.py:18:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+17 | Path(  # Comment before argument
+18 |     '',
+   |     ^^ PTH201
+19 | )
+   |
+   = help: Remove the current directory argument
+
+ℹ Unsafe fix
+14 14 |     '',
+15 15 | )
+16 16 | 
+17    |-Path(  # Comment before argument
+18    |-    '',
+19    |-)
+   17 |+Path()
+20 18 | 
+21 19 | Path(
+22 20 |     '',  # EOL comment
+
+PTH201.py:22:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+21 | Path(
+22 |     '',  # EOL comment
+   |     ^^ PTH201
+23 | )
+   |
+   = help: Remove the current directory argument
+
+ℹ Unsafe fix
+18 18 |     '',
+19 19 | )
+20 20 | 
+21    |-Path(
+22    |-    '',  # EOL comment
+23    |-)
+   21 |+Path()
+24 22 | 
+25 23 | Path(
+26 24 |     ''  # Comment in the middle of implicitly concatenated string
+
+PTH201.py:26:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+25 |   Path(
+26 |       ''  # Comment in the middle of implicitly concatenated string
+   |  _____^
+27 | |     ".",
+   | |_______^ PTH201
+28 |   )
+   |
+   = help: Remove the current directory argument
+
+ℹ Unsafe fix
+22 22 |     '',  # EOL comment
+23 23 | )
+24 24 | 
+25    |-Path(
+26    |-    ''  # Comment in the middle of implicitly concatenated string
+27    |-    ".",
+28    |-)
+   25 |+Path()
+29 26 | 
+30 27 | Path(
+31 28 |     ''  # Comment before comma
+
+PTH201.py:31:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+30 | Path(
+31 |     ''  # Comment before comma
+   |     ^^ PTH201
+32 |     ,
+33 | )
+   |
+   = help: Remove the current directory argument
+
+ℹ Unsafe fix
+27 27 |     ".",
+28 28 | )
+29 29 | 
+30    |-Path(
+31    |-    ''  # Comment before comma
+32    |-    ,
+33    |-)
+   30 |+Path()
+34 31 | 
+35 32 | Path(
+36 33 |     '',
+
+PTH201.py:36:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+35 | Path(
+36 |     '',
+   |     ^^ PTH201
+37 | ) / "bare"
+   |
+   = help: Remove the current directory argument
+
+ℹ Safe fix
+33 33 | )
+34 34 | 
+35 35 | Path(
+36    |-    '',
+37    |-) / "bare"
+   36 |+    "bare",
+   37 |+)
+38 38 | 
+39 39 | Path(  # Comment before argument
+40 40 |     '',
+
+PTH201.py:40:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+39 | Path(  # Comment before argument
+40 |     '',
+   |     ^^ PTH201
+41 | ) / ("parenthesized")
+   |
+   = help: Remove the current directory argument
+
+ℹ Unsafe fix
+37 37 | ) / "bare"
+38 38 | 
+39 39 | Path(  # Comment before argument
+40    |-    '',
+41    |-) / ("parenthesized")
+   40 |+    ("parenthesized"),
+   41 |+)
+42 42 | 
+43 43 | Path(
+44 44 |     '',  # EOL comment
+
+PTH201.py:44:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+43 | Path(
+44 |     '',  # EOL comment
+   |     ^^ PTH201
+45 | ) / ( ("double parenthesized"  )   )
+   |
+   = help: Remove the current directory argument
+
+ℹ Unsafe fix
+41 41 | ) / ("parenthesized")
+42 42 | 
+43 43 | Path(
+44    |-    '',  # EOL comment
+45    |-) / ( ("double parenthesized"  )   )
+   44 |+    ( ("double parenthesized"  )   ),  # EOL comment
+   45 |+)
+46 46 | 
+47 47 | (  Path(
+48 48 |     ''  # Comment in the middle of implicitly concatenated string
+
+PTH201.py:48:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+47 |   (  Path(
+48 |       ''  # Comment in the middle of implicitly concatenated string
+   |  _____^
+49 | |     ".",
+   | |_______^ PTH201
+50 |   ) )/ (("parenthesized path call")
+51 |         # Comment between closing parentheses
+   |
+   = help: Remove the current directory argument
+
+ℹ Unsafe fix
+44 44 |     '',  # EOL comment
+45 45 | ) / ( ("double parenthesized"  )   )
+46 46 | 
+47    |-(  Path(
+48    |-    ''  # Comment in the middle of implicitly concatenated string
+49    |-    ".",
+50    |-) )/ (("parenthesized path call")
+   47 |+Path(
+   48 |+    (("parenthesized path call")
+51 49 |       # Comment between closing parentheses
+   50 |+),
+52 51 | )
+53 52 | 
+54 53 | Path(
+
+PTH201.py:55:5: PTH201 [*] Do not pass the current directory explicitly to `Path`
+   |
+54 | Path(
+55 |     ''  # Comment before comma
+   |     ^^ PTH201
+56 |     ,
+57 | ) / "multiple" / (
+   |
+   = help: Remove the current directory argument
+
+ℹ Unsafe fix
+52 52 | )
+53 53 | 
+54 54 | Path(
+55    |-    ''  # Comment before comma
+   55 |+    "multiple"  # Comment before comma
+56 56 |     ,
+57    |-) / "multiple" / (
+   57 |+) / (
+58 58 |     "frag"  # Comment
+59 59 |     'ment'
+60 60 | )