Author: Jameson Nash Date: 2025-02-07T08:01:39+01:00 New Revision: 9b8297bc7ea8f217a3f701afedd2c953a4ad7867
URL: https://github.com/llvm/llvm-project/commit/9b8297bc7ea8f217a3f701afedd2c953a4ad7867 DIFF: https://github.com/llvm/llvm-project/commit/9b8297bc7ea8f217a3f701afedd2c953a4ad7867.diff LOG: [analyzer] Do not destruct fields of unions (#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 Added: clang/test/Analysis/dtor-union.cpp Modified: clang/docs/ReleaseNotes.rst clang/lib/Analysis/CFG.cpp clang/test/Analysis/NewDelete-checker-test.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 6d7eb84927a978..92f63c15030898 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -127,6 +127,7 @@ Improvements to Clang's diagnostics - The ``-Wunique-object-duplication`` warning has been added to warn about objects which are supposed to only exist once per program, but may get duplicated when built into a shared library. +- Fixed a bug where Clang's Analysis did not correctly model the destructor behavior of ``union`` members (#GH119415). Improvements to Clang's time-trace ---------------------------------- 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..06754f669b1e61 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-union.cpp b/clang/test/Analysis/dtor-union.cpp new file mode 100644 index 00000000000000..dac366e6f9df89 --- /dev/null +++ b/clang/test/Analysis/dtor-union.cpp @@ -0,0 +1,38 @@ +// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -analyzer-config c++-inlining=destructors -verify -std=c++11 %s +// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -analyzer-config c++-inlining=destructors -verify -std=c++17 %s + +void clang_analyzer_eval(bool); + +struct InlineDtor { + static int cnt; + static int dtorCalled; + ~InlineDtor() { + ++dtorCalled; + } +}; + +int InlineDtor::cnt = 0; +int InlineDtor::dtorCalled = 0; + +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 == 0); // expected-warning {{TRUE}} +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
