[clang] [Clang] Fix missing -Warray-bounds warning on member function calls. (PR #179647)

[Prajwal P J via cfe-commits]

https://github.com/pjalwadi updated https://github.com/llvm/llvm-project/pull/179647

>From 88a473609cf91bec52bc4783296fda5762397e23 Mon Sep 17 00:00:00 2001
From: prajwal jalwadi <prajwaljalwadi at gmail.com>
Date: Wed, 4 Feb 2026 15:27:57 +0530
Subject: [PATCH] [Clang] Fix missing -Warray-bounds warning on member function
 calls

Fixes #179128.
This patch fixes a false negative where Clang failed to detect out-of-bounds access when calling a member function on an invalid array index. It adds handling for CXXMemberCallExpr in CheckArrayAccess.

Signed-off-by: prajwal jalwadi<prajwaljalwadi at gmail.com>
---
 clang/lib/Sema/SemaChecking.cpp                  | 4 ++++
 clang/test/SemaCXX/constant-expression-cxx2a.cpp | 5 +++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 3f19b6ad16c13..cec6060cc9dab 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -15449,6 +15449,10 @@ void Sema::CheckArrayAccess(const Expr *expr) {
         expr = cast<MemberExpr>(expr)->getBase();
         break;
       }
+      case Stmt::CXXMemberCallExprClass: {
+        expr = cast<CXXMemberCallExpr>(expr)->getImplicitObjectArgument();
+        break;
+      }
       case Stmt::ArraySectionExprClass: {
         const ArraySectionExpr *ASE = cast<ArraySectionExpr>(expr);
         // FIXME: We should probably be checking all of the elements to the
diff --git a/clang/test/SemaCXX/constant-expression-cxx2a.cpp b/clang/test/SemaCXX/constant-expression-cxx2a.cpp
index 4fcd243b4442c..75be84557a0ec 100644
--- a/clang/test/SemaCXX/constant-expression-cxx2a.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx2a.cpp
@@ -1241,8 +1241,9 @@ namespace dtor_call {
   }
 
   constexpr void destroy_past_end_array() { // expected-error {{never produces a constant expression}}
-    A a[2];
-    a[2].~A(); // expected-note {{destruction of dereferenced one-past-the-end pointer}}
+  A a[2]; // expected-note {{array 'a' declared here}}
+  a[2].~A(); // expected-note {{destruction of dereferenced one-past-the-end pointer}} \
+             // expected-warning {{array index 2 is past the end of the array}}
   }
 
   union As {