https://github.com/vtjnash created
https://github.com/llvm/llvm-project/pull/122330
The C++ standard prohibits this implicit destructor call, leading to incorrect
reports from clang-analyzer. This causes projects that use std::option
(including llvm) to fail the cplusplus.NewDelete test incorrectly when run
through the analyzer.
Fixes #119415
>From 533e475ffa57da335a2cce387f08c83f442fd16b Mon Sep 17 00:00:00 2001
From: Jameson Nash <vtjn...@gmail.com>
Date: Thu, 9 Jan 2025 17:10:08 +0000
Subject: [PATCH] [Sema] do not destruct fields of unions
The C++ standard prohibits this implicit destructor call, leading to
incorrect reports from clang-analyzer. This causes projects that use
std::option (including llvm) to fail the cplusplus.NewDelete test
incorrectly when run through the analyzer.
Fixes #119415
---
clang/lib/Analysis/CFG.cpp | 2 ++
.../test/Analysis/NewDelete-checker-test.cpp | 28 +++++++++++++++++++
clang/test/Analysis/dtor-array.cpp | 24 ++++++++++++++++
3 files changed, 54 insertions(+)
diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index 304bbb2b422c61..3e144395cffc6f 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -2041,6 +2041,8 @@ void CFGBuilder::addImplicitDtorsForDestructor(const
CXXDestructorDecl *DD) {
}
// First destroy member objects.
+ if (RD->isUnion())
+ return;
for (auto *FI : RD->fields()) {
// Check for constant size array. Set type to array element type.
QualType QT = FI->getType();
diff --git a/clang/test/Analysis/NewDelete-checker-test.cpp
b/clang/test/Analysis/NewDelete-checker-test.cpp
index 21b4cf817b5df6..806edd47840fc1 100644
--- a/clang/test/Analysis/NewDelete-checker-test.cpp
+++ b/clang/test/Analysis/NewDelete-checker-test.cpp
@@ -441,3 +441,31 @@ void testLeakBecauseNTTPIsNotDeallocation() {
void* p = ::operator new(10);
deallocate_via_nttp<not_free>(p);
} // leak-warning{{Potential leak of memory pointed to by 'p'}}
+
+namespace optional_union {
+ template <typename T>
+ class unique_ptr {
+ T *q;
+ public:
+ unique_ptr() : q(new T) {}
+ ~unique_ptr() {
+ delete q;
+ }
+ };
+
+ union custom_union_t {
+ unique_ptr<int> present;
+ char notpresent;
+ custom_union_t() : present(unique_ptr<int>()) {}
+ ~custom_union_t() {};
+ };
+
+ void testUnionCorrect() {
+ custom_union_t a;
+ a.present.~unique_ptr<int>();
+ }
+
+ void testUnionLeak() {
+ custom_union_t a;
+ } // leak-warning{{Potential leak of memory pointed to by 'a.present.q'}}
+}
diff --git a/clang/test/Analysis/dtor-array.cpp
b/clang/test/Analysis/dtor-array.cpp
index 84a34af9225169..1bbe55c09ee7e2 100644
--- a/clang/test/Analysis/dtor-array.cpp
+++ b/clang/test/Analysis/dtor-array.cpp
@@ -377,3 +377,27 @@ void directUnknownSymbol() {
}
}
+
+void testUnionDtor() {
+ static int unionDtorCalled;
+ InlineDtor::cnt = 0;
+ InlineDtor::dtorCalled = 0;
+ unionDtorCalled = 0;
+ {
+ union UnionDtor {
+ InlineDtor kind1;
+ char kind2;
+ ~UnionDtor() { unionDtorCalled++; }
+ };
+ UnionDtor u1{.kind1{}};
+ UnionDtor u2{.kind2{}};
+ auto u3 = new UnionDtor{.kind1{}};
+ auto u4 = new UnionDtor{.kind2{}};
+ delete u3;
+ delete u4;
+ }
+
+ clang_analyzer_eval(unionDtorCalled == 4); // expected-warning {{TRUE}}
+ clang_analyzer_eval(InlineDtor::dtorCalled != 4); // expected-warning
{{TRUE}}
+ clang_analyzer_eval(InlineDtor::dtorCalled == 0); // expected-warning
{{TRUE}}
+}
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
