Author: Haojian Wu Date: 2024-12-20T09:26:38+01:00 New Revision: a6d26c56ff066c8e8f92f4ca169fcf40ae0db537
URL: https://github.com/llvm/llvm-project/commit/a6d26c56ff066c8e8f92f4ca169fcf40ae0db537 DIFF: https://github.com/llvm/llvm-project/commit/a6d26c56ff066c8e8f92f4ca169fcf40ae0db537.diff LOG: [clang] Fix dangling false positives for conditional operators. (#120233) When analyzing a dangling gsl pointer, we currently filter out all field access `MemberExpr` to avoid common false positives (`string_view sv = Temp().sv`), However, this filter only applies to direct MemberExpr instances, leaving the conditional operator as an escaping example (`GSLPointer pointer(Cond ? Owner().ptr : GSLPointer());`). This patch extends the MemberExpr logic to handle the conditional operator. The heuristic is intentionally simple, which may result in some false negatives. However, it effectively covers common cases like `std::string_view sv = cond ? "123" : std::string();`, which is a reasonable trade-off. Fixes https://github.com/llvm/llvm-project/issues/120206 Added: Modified: clang/docs/ReleaseNotes.rst clang/lib/Sema/CheckExprLifetime.cpp clang/test/Sema/warn-lifetime-analysis-nocfg.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index b8d92a6c881c68..a85ef60b7b58ba 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -706,6 +706,8 @@ Improvements to Clang's diagnostics return ptr + index < ptr; // warning } +- Fix -Wdangling false positives on conditional operators (#120206). + Improvements to Clang's time-trace ---------------------------------- diff --git a/clang/lib/Sema/CheckExprLifetime.cpp b/clang/lib/Sema/CheckExprLifetime.cpp index add6d7506bd6f0..7109de03cadd12 100644 --- a/clang/lib/Sema/CheckExprLifetime.cpp +++ b/clang/lib/Sema/CheckExprLifetime.cpp @@ -582,6 +582,15 @@ static void visitFunctionCallArguments(IndirectLocalPath &Path, Expr *Call, // Temp().ptr; // Here ptr might not dangle. if (isa<MemberExpr>(Arg->IgnoreImpCasts())) return; + // Avoid false positives when the object is constructed from a conditional + // operator argument. A common case is: + // // 'ptr' might not be owned by the Owner object. + // std::string_view s = cond() ? Owner().ptr : sv; + if (const auto *Cond = + dyn_cast<AbstractConditionalOperator>(Arg->IgnoreImpCasts()); + Cond && isPointerLikeType(Cond->getType())) + return; + auto ReturnType = Callee->getReturnType(); // Once we initialized a value with a non gsl-owner reference, it can no diff --git a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp index 45b4dc838f44ed..4c19367bb7f3dd 100644 --- a/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp +++ b/clang/test/Sema/warn-lifetime-analysis-nocfg.cpp @@ -777,3 +777,32 @@ void test4() { } } // namespace LifetimeboundInterleave + +namespace GH120206 { +struct S { + std::string_view s; +}; + +struct [[gsl::Owner]] Q1 { + const S* get() const [[clang::lifetimebound]]; +}; +std::string_view test1(int c, std::string_view sv) { + std::string_view k = c > 1 ? Q1().get()->s : sv; + if (c == 1) + return c > 1 ? Q1().get()->s : sv; + Q1 q; + return c > 1 ? q.get()->s : sv; +} + +struct Q2 { + const S* get() const [[clang::lifetimebound]]; +}; +std::string_view test2(int c, std::string_view sv) { + std::string_view k = c > 1 ? Q2().get()->s : sv; + if (c == 1) + return c > 1 ? Q2().get()->s : sv; + Q2 q; + return c > 1 ? q.get()->s : sv; +} + +} // namespace GH120206 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
