[clang] [OpenCL] Suppress -Wreturn-stack-address for function-scope local variable (PR #181602)

[Wenju He via cfe-commits]

https://github.com/wenju-he updated https://github.com/llvm/llvm-project/pull/181602

>From 2b014e12d738f03e1a6b17eae3f61c8401e287b5 Mon Sep 17 00:00:00 2001
From: Wenju He <wenju.he at intel.com>
Date: Mon, 16 Feb 2026 07:18:28 +0100
Subject: [PATCH 1/2] [OpenCL] Suppress -Wreturn-stack-address for
 function-scope local variable

when __cl_clang_function_scope_local_variables extension is enabled.

OpenCL local variable has lifetime of work-group, not function call stack.
---
 clang/lib/Sema/CheckExprLifetime.cpp                |  7 +++++++
 .../test/SemaOpenCL/function-scope-local-return.cl  | 13 +++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 clang/test/SemaOpenCL/function-scope-local-return.cl

diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp
index 5d4b4508541b7..c2f2aa8fc9487 100644
--- a/clang/lib/Sema/CheckExprLifetime.cpp
+++ b/clang/lib/Sema/CheckExprLifetime.cpp
@@ -1337,6 +1337,13 @@ checkExprLifetimeImpl(Sema &SemaRef, const InitializedEntity *InitEntity,
         // expression.
         if (LK == LK_StmtExprResult)
           return false;
+        if (auto *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
+          if (VD->getType().getAddressSpace() == LangAS::opencl_local &&
+              SemaRef.getOpenCLOptions().isAvailableOption(
+                  "__cl_clang_function_scope_local_variables",
+                  SemaRef.getLangOpts()))
+            return false;
+        }
         SemaRef.Diag(DiagLoc, diag::warn_ret_stack_addr_ref)
             << InitEntity->getType()->isReferenceType() << DRE->getDecl()
             << isa<ParmVarDecl>(DRE->getDecl()) << (LK == LK_MustTail)
diff --git a/clang/test/SemaOpenCL/function-scope-local-return.cl b/clang/test/SemaOpenCL/function-scope-local-return.cl
new file mode 100644
index 0000000000000..1de86b4293a9a
--- /dev/null
+++ b/clang/test/SemaOpenCL/function-scope-local-return.cl
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only -cl-std=CL3.0
+
+// Check returning a pointer to a local address space variable does not warn
+// if __cl_clang_function_scope_local_variables extension is enabled.
+
+// expected-no-diagnostics
+
+#pragma OPENCL EXTENSION __cl_clang_function_scope_local_variables : enable
+
+local int* get_group_scratch() {
+  local int data[64];
+  return data;
+}

>From 69dadbb4ffda1af0d1bc0e268facb0a6bc29ad76 Mon Sep 17 00:00:00 2001
From: Wenju He <wenju.he at intel.com>
Date: Thu, 19 Feb 2026 03:51:17 +0100
Subject: [PATCH 2/2] drop __cl_clang_function_scope_local_variables check

---
 clang/lib/Sema/CheckExprLifetime.cpp                 | 8 ++------
 clang/test/SemaOpenCL/function-scope-local-return.cl | 4 ++--
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp
index c2f2aa8fc9487..4e050e9bf6045 100644
--- a/clang/lib/Sema/CheckExprLifetime.cpp
+++ b/clang/lib/Sema/CheckExprLifetime.cpp
@@ -1337,13 +1337,9 @@ checkExprLifetimeImpl(Sema &SemaRef, const InitializedEntity *InitEntity,
         // expression.
         if (LK == LK_StmtExprResult)
           return false;
-        if (auto *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
-          if (VD->getType().getAddressSpace() == LangAS::opencl_local &&
-              SemaRef.getOpenCLOptions().isAvailableOption(
-                  "__cl_clang_function_scope_local_variables",
-                  SemaRef.getLangOpts()))
+        if (auto *VD = dyn_cast<VarDecl>(DRE->getDecl()))
+          if (VD->getType().getAddressSpace() == LangAS::opencl_local)
             return false;
-        }
         SemaRef.Diag(DiagLoc, diag::warn_ret_stack_addr_ref)
             << InitEntity->getType()->isReferenceType() << DRE->getDecl()
             << isa<ParmVarDecl>(DRE->getDecl()) << (LK == LK_MustTail)
diff --git a/clang/test/SemaOpenCL/function-scope-local-return.cl b/clang/test/SemaOpenCL/function-scope-local-return.cl
index 1de86b4293a9a..8b3c5e6cbe2f0 100644
--- a/clang/test/SemaOpenCL/function-scope-local-return.cl
+++ b/clang/test/SemaOpenCL/function-scope-local-return.cl
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 %s -verify -pedantic -fsyntax-only -cl-std=CL3.0
 
-// Check returning a pointer to a local address space variable does not warn
-// if __cl_clang_function_scope_local_variables extension is enabled.
+// Check tjat returning a pointer to a local address space variable does not
+// trigger -Wreturn-stack-address.
 
 // expected-no-diagnostics