[clang-tools-extra] [clang-tidy] Fix false positive for cppcoreguidelines-pro-bounds-pointer-arithmetic (PR #127394)

[via cfe-commits]

https://github.com/flovent created https://github.com/llvm/llvm-project/pull/127394

this PR fixs #126424
for `ArraySubScriptExpr`, `hasBase` Matcher will get right operand when it is not Integer type, but is not for sure that left operand is interger type. For the example code below `hasBase` will get `r` for the Subsequent matching and causing false positive.
```
template <typename R>
int f(std::map<R*, int>& map, R* r) {
  return map[r];
}
```
so is needed to see if index is interger type to avoid this situation.

>From 1bd661b60dbb350dcefad3556218bbec71a4f366 Mon Sep 17 00:00:00 2001
From: flovent <flbven at protonmail.com>
Date: Sun, 16 Feb 2025 21:07:55 +0800
Subject: [PATCH] [clang-tidy] Fix false positive for
 cppcoreguidelines-pro-bounds-pointer-arithmetic

---
 .../ProBoundsPointerArithmeticCheck.cpp       |  3 ++-
 clang-tools-extra/docs/ReleaseNotes.rst       |  4 ++++
 ...-bounds-pointer-arithmetic-issue126424.cpp | 19 +++++++++++++++++++
 3 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-bounds-pointer-arithmetic-issue126424.cpp

diff --git a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
index a1494a095f5b6..0d68790349fb5 100644
--- a/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
+++ b/clang-tools-extra/clang-tidy/cppcoreguidelines/ProBoundsPointerArithmeticCheck.cpp
@@ -42,7 +42,8 @@ void ProBoundsPointerArithmeticCheck::registerMatchers(MatchFinder *Finder) {
       arraySubscriptExpr(
           hasBase(ignoringImpCasts(
               anyOf(AllPointerTypes,
-                    hasType(decayedType(hasDecayedType(pointerType())))))))
+                    hasType(decayedType(hasDecayedType(pointerType())))))),
+          hasIndex(hasType(isInteger())))
           .bind("expr"),
       this);
 }
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index 6b8fe22242417..937d710fe6100 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -110,6 +110,10 @@ Changes in existing checks
   <clang-tidy/checks/misc/redundant-expression>` check by providing additional
   examples and fixing some macro related false positives.
 
+- Improved :doc:`cppcoreguidelines-pro-bounds-pointer-arithmetic
+  <clang-tidy/checks/cppcoreguidelines/pro-bounds-pointer-arithmetic>` check by
+  fix false positives related to operator overloading and templates.
+
 Removed checks
 ^^^^^^^^^^^^^^
 
diff --git a/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-bounds-pointer-arithmetic-issue126424.cpp b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-bounds-pointer-arithmetic-issue126424.cpp
new file mode 100644
index 0000000000000..b6b7a9664f38d
--- /dev/null
+++ b/clang-tools-extra/test/clang-tidy/checkers/cppcoreguidelines/pro-bounds-pointer-arithmetic-issue126424.cpp
@@ -0,0 +1,19 @@
+// RUN: %check_clang_tidy %s cppcoreguidelines-pro-bounds-pointer-arithmetic %t
+
+namespace std {
+template <typename, typename>
+class pair {};
+
+template <typename Key, typename Value>
+class map {
+  public:
+   using value_type = pair<Key, Value>;
+   value_type& operator[](const Key& key);
+   value_type& operator[](Key&& key);
+ };
+}
+
+template <typename R>
+int f(std::map<R*, int>& map, R* r) {
+  return map[r]; // OK
+}
\ No newline at end of file