[llvm-branch-commits] [clang-tools-extra] [clang-tidy] `use-ranges`: preserve remove iterator results (PR #196036)

[Daniil Dudkin via llvm-branch-commits]

https://github.com/unterumarmung created https://github.com/llvm/llvm-project/pull/196036

Preserve used iterator results for remove, partition, stable_partition, and rotate-style replacements by appending .begin() where the ranges algorithm returns a subrange.

Fix #124794

Assisted by Codex.

>From 4e67380300697ba93a907b2eb8ae43cb3bb2edf9 Mon Sep 17 00:00:00 2001
From: Daniil Dudkin <unterumarmung at yandex.ru>
Date: Wed, 6 May 2026 00:27:35 +0300
Subject: [PATCH] [clang-tidy] `use-ranges`: preserve remove iterator results

Preserve used iterator results for remove, partition, stable_partition, and rotate-style replacements by appending .begin() where the ranges algorithm returns a subrange.

Fix #124794

Assisted by Codex.
---
 .../clang-tidy/modernize/UseRangesCheck.cpp   | 12 ++++-----
 clang-tools-extra/docs/ReleaseNotes.rst       |  4 +++
 .../modernize/Inputs/use-ranges/fake_std.h    | 16 ++++++++++++
 .../checkers/modernize/use-ranges.cpp         | 25 +++++++++++++++++++
 4 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/clang-tools-extra/clang-tidy/modernize/UseRangesCheck.cpp b/clang-tools-extra/clang-tidy/modernize/UseRangesCheck.cpp
index 27fc52d95921e..e36ce3adeb15f 100644
--- a/clang-tools-extra/clang-tidy/modernize/UseRangesCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/UseRangesCheck.cpp
@@ -37,8 +37,6 @@ static constexpr const char *SingleRangeNames[] = {
     "replace",
     "replace_if",
     "generate",
-    "remove",
-    "remove_if",
     "remove_copy",
     "remove_copy_if",
     "unique_copy",
@@ -59,9 +57,7 @@ static constexpr const char *SingleRangeNames[] = {
     "shift_left",
     "shift_right",
     "is_partitioned",
-    "partition",
     "partition_copy",
-    "stable_partition",
     "sort",
     "stable_sort",
     "is_sorted",
@@ -79,7 +75,8 @@ static constexpr const char *SingleRangeNames[] = {
     "destroy",
 };
 
-static constexpr const char *SingleRangeBeginResultNames[] = {"unique"};
+static constexpr const char *SingleRangeBeginResultNames[] = {
+    "remove", "remove_if", "stable_partition", "partition", "unique"};
 
 static constexpr const char *TwoRangeNames[] = {
     "equal",
@@ -97,9 +94,11 @@ static constexpr const char *TwoRangeNames[] = {
     "is_permutation",
 };
 
-static constexpr const char *SinglePivotRangeNames[] = {"rotate", "rotate_copy",
+static constexpr const char *SinglePivotRangeNames[] = {"rotate_copy",
                                                         "inplace_merge"};
 
+static constexpr const char *SinglePivotRangeBeginResultNames[] = {"rotate"};
+
 namespace {
 class StdReplacer : public utils::UseRangesCheck::Replacer {
 public:
@@ -176,6 +175,7 @@ utils::UseRangesCheck::ReplacerMap UseRangesCheck::getReplacerMap() const {
       {SingleRangeFunc, SingleRangeBeginResultNames, BeginResultPolicy},
       {TwoRangeFunc, TwoRangeNames, DefaultPolicy},
       {SinglePivotFunc, SinglePivotRangeNames, DefaultPolicy},
+      {SinglePivotFunc, SinglePivotRangeBeginResultNames, BeginResultPolicy},
   };
   SmallString<64> Buff;
   for (const auto &[Signatures, Values, Policy] : AlgorithmNames) {
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 62aada7cf3a82..9742b71df4e64 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -438,6 +438,10 @@ Changes in existing checks
   - Preserved used iterator results when replacing ``std::unique`` calls with
     ``std::ranges::unique``.
 
+  - Preserved used iterator results when replacing ``std::remove``,
+    ``std::remove_if``, ``std::partition``, ``std::stable_partition``, and
+    ``std::rotate`` calls with their ``std::ranges`` counterparts.
+
 - Improved :doc:`modernize-use-std-format
   <clang-tidy/checks/modernize/use-std-format>` check:
 
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/Inputs/use-ranges/fake_std.h b/clang-tools-extra/test/clang-tidy/checkers/modernize/Inputs/use-ranges/fake_std.h
index 648a399f9fcff..23ca215268c0c 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/Inputs/use-ranges/fake_std.h
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/Inputs/use-ranges/fake_std.h
@@ -92,6 +92,22 @@ void iota(ForwardIt first, ForwardIt last, T value);
 template <class ForwardIt>
 ForwardIt unique(ForwardIt first, ForwardIt last);
 
+template <class ForwardIt, class T>
+ForwardIt remove(ForwardIt first, ForwardIt last, const T &value);
+template <class ForwardIt, class UnaryPred>
+ForwardIt remove_if(ForwardIt first, ForwardIt last, UnaryPred pred) {
+  return first;
+}
+
+template <class ForwardIt, class UnaryPred>
+ForwardIt partition(ForwardIt first, ForwardIt last, UnaryPred pred) {
+  return first;
+}
+template <class BidirIt, class UnaryPred>
+BidirIt stable_partition(BidirIt first, BidirIt last, UnaryPred pred) {
+  return first;
+}
+
 template <class ForwardIt>
 ForwardIt rotate(ForwardIt first, ForwardIt middle, ForwardIt last);
 } // namespace _V1
diff --git a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-ranges.cpp b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-ranges.cpp
index be293e19a65a6..c48db04c483b8 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/modernize/use-ranges.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/modernize/use-ranges.cpp
@@ -55,6 +55,27 @@ void Positives() {
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use a ranges version of this algorithm
   // CHECK-FIXES: std::ranges::unique(I);
 
+  I.erase(std::remove(I.begin(), I.end(), 0), I.end());
+  // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: use a ranges version of this algorithm
+  // CHECK-FIXES: I.erase(std::ranges::remove(I, 0).begin(), I.end());
+
+  I.erase(std::remove_if(I.begin(), I.end(), [](int N) { return N == 0; }),
+          I.end());
+  // CHECK-MESSAGES: :[[@LINE-2]]:11: warning: use a ranges version of this algorithm
+  // CHECK-FIXES: I.erase(std::ranges::remove_if(I, [](int N) { return N == 0; }).begin(),
+
+  auto PartitionPoint =
+      std::partition(I.begin(), I.end(), [](int N) { return N == 0; });
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a ranges version of this algorithm
+  // CHECK-FIXES: auto PartitionPoint =
+  // CHECK-FIXES-NEXT: std::ranges::partition(I, [](int N) { return N == 0; }).begin();
+
+  auto StablePartitionPoint =
+      std::stable_partition(I.begin(), I.end(), [](int N) { return N == 0; });
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use a ranges version of this algorithm
+  // CHECK-FIXES: auto StablePartitionPoint =
+  // CHECK-FIXES-NEXT: std::ranges::stable_partition(I, [](int N) { return N == 0; }).begin();
+
   std::includes(I.begin(), I.end(), I.begin(), I.end());
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use a ranges version of this algorithm
   // CHECK-FIXES: std::ranges::includes(I, I);
@@ -83,6 +104,10 @@ void Positives() {
   // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: use a ranges version of this algorithm
   // CHECK-FIXES: std::ranges::rotate(I, I.begin() + 2);
 
+  auto RotatePoint = std::rotate(I.begin(), I.begin() + 2, I.end());
+  // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: use a ranges version of this algorithm
+  // CHECK-FIXES: auto RotatePoint = std::ranges::rotate(I, I.begin() + 2).begin();
+
   using std::find;
   namespace my_std = std;