From dd6a58babc853d180b9a7e5bd709ae12477da004 Mon Sep 17 00:00:00 2001
From: Peter Kasting <pkasting@chromium.org>
Date: Sat, 6 May 2023 20:12:14 +0530
Subject: [PATCH] [Sema] Avoid emitting warnings for constant destruction.

Fixes https://github.com/llvm/llvm-project/issues/62436.

Reviewed By: rsmith

Differential Revision: https://reviews.llvm.org/D149713
---
 clang/lib/Sema/SemaDeclCXX.cpp                |  3 ++-
 .../SemaCXX/warn-exit-time-destructors.cpp    | 22 ++++++++++++++++++-
 .../test/SemaCXX/warn-global-constructors.cpp | 22 ++++++++++++++++++-
 3 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index dcb3e676b0ba48..31936bce786213 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -15732,7 +15732,8 @@ void Sema::FinalizeVarWithDestructor(VarDecl *VD, const RecordType *Record) {
     }
   }
 
-  if (!VD->hasGlobalStorage()) return;
+  if (!VD->hasGlobalStorage() || !VD->needsDestruction(Context))
+    return;
 
   // Emit warning for non-trivial dtor in global scope (a real global,
   // class-static, function-static).
diff --git a/clang/test/SemaCXX/warn-exit-time-destructors.cpp b/clang/test/SemaCXX/warn-exit-time-destructors.cpp
index 17b3a9406369fa..2f14243cb48c47 100644
--- a/clang/test/SemaCXX/warn-exit-time-destructors.cpp
+++ b/clang/test/SemaCXX/warn-exit-time-destructors.cpp
@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -Wexit-time-destructors %s -verify
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -Wexit-time-destructors %s -verify=expected,cxx11
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -Wexit-time-destructors %s -verify=expected
 
 namespace test1 {
   struct A { ~A(); };
@@ -48,3 +49,22 @@ namespace test4 {
 struct A { ~A(); };
 [[clang::no_destroy]] A a; // no warning
 }
+
+namespace test5 {
+#if __cplusplus >= 202002L
+#define CPP20_CONSTEXPR constexpr
+#else
+#define CPP20_CONSTEXPR
+#endif
+  struct S {
+    CPP20_CONSTEXPR ~S() {}
+  };
+  S s; // cxx11-warning {{exit-time destructor}}
+
+  struct T {
+    CPP20_CONSTEXPR ~T() { if (b) {} }
+    bool b;
+  };
+  T t; // expected-warning {{exit-time destructor}}
+#undef CPP20_CONSTEXPR
+}
diff --git a/clang/test/SemaCXX/warn-global-constructors.cpp b/clang/test/SemaCXX/warn-global-constructors.cpp
index 430f239a3ed7e1..765654b5e9f4fe 100644
--- a/clang/test/SemaCXX/warn-global-constructors.cpp
+++ b/clang/test/SemaCXX/warn-global-constructors.cpp
@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -Wglobal-constructors %s -verify
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -Wglobal-constructors %s -verify=expected,cxx11
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -Wglobal-constructors %s -verify=expected
 
 int opaque_int();
 
@@ -145,3 +146,22 @@ namespace bitfields {
   const HasUnnamedBitfield nonConstexprConst{1}; // expected-warning {{global constructor}}
   HasUnnamedBitfield nonConstexprMutable{1}; // expected-warning {{global constructor}}
 }
+
+namespace test7 {
+#if __cplusplus >= 202002L
+#define CPP20_CONSTEXPR constexpr
+#else
+#define CPP20_CONSTEXPR
+#endif
+  struct S {
+    CPP20_CONSTEXPR ~S() {}
+  };
+  S s; // cxx11-warning {{global destructor}}
+
+  struct T {
+    CPP20_CONSTEXPR ~T() { if (b) {} }
+    bool b;
+  };
+  T t; // expected-warning {{global destructor}}
+#undef CPP20_CONSTEXPR
+}