From f7613d53619d11f46fb07ddb0ea90c9fb0cad027 Mon Sep 17 00:00:00 2001
From: Anders Carlsson <andersca@mac.com>
Date: Sat, 7 Nov 2009 07:26:56 +0000
Subject: [PATCH] Don't treat variables with non-trivial ctors or dtors as
 unused. Fixes PR5407.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@86352 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDecl.cpp                  | 18 ++++++++++++++++--
 test/SemaCXX/warn-unused-variables.cpp |  8 ++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index df7be10223..8e1a19cbe5 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -385,8 +385,22 @@ bool Sema::isDeclInScope(NamedDecl *&D, DeclContext *Ctx, Scope *S) {
 }
 
 static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
-  return (!D->isUsed() && !D->hasAttr<UnusedAttr>() && isa<VarDecl>(D) && 
-          !isa<ParmVarDecl>(D) && !isa<ImplicitParamDecl>(D) && 
+  if (D->isUsed() || D->hasAttr<UnusedAttr>())
+    return false;
+  
+  if (const ValueDecl *VD = dyn_cast<ValueDecl>(D)) {
+    if (const RecordType *RT = VD->getType()->getAs<RecordType>()) {
+      if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
+        if (!RD->hasTrivialConstructor())
+          return false;
+        if (!RD->hasTrivialDestructor())
+          return false;
+      }
+    }
+  }
+  
+  return (isa<VarDecl>(D) && !isa<ParmVarDecl>(D) && 
+          !isa<ImplicitParamDecl>(D) && 
           D->getDeclContext()->isFunctionOrMethod());
 }
 
diff --git a/test/SemaCXX/warn-unused-variables.cpp b/test/SemaCXX/warn-unused-variables.cpp
index d8b9a00ad6..001048910c 100644
--- a/test/SemaCXX/warn-unused-variables.cpp
+++ b/test/SemaCXX/warn-unused-variables.cpp
@@ -4,3 +4,11 @@ template<typename T> void f() {
 	T t;
 	t = 17;
 }
+
+struct A { A(); };
+struct B { ~B(); };
+
+void f() {
+  A a;
+  B b;
+}
\ No newline at end of file
-- 
2.50.1