Author: Boaz Brickner Date: 2024-10-25T15:31:57+02:00 New Revision: 9043bdbce4ab1c6f07e72ddfedf7165bdf2b3e40
URL: https://github.com/llvm/llvm-project/commit/9043bdbce4ab1c6f07e72ddfedf7165bdf2b3e40 DIFF: https://github.com/llvm/llvm-project/commit/9043bdbce4ab1c6f07e72ddfedf7165bdf2b3e40.diff LOG: [clang] Output an error when [[lifetimebound]] attribute is applied on a function parameter while the function returns void (#113460) Fixes: https://github.com/llvm/llvm-project/issues/107556 Added: Modified: clang/docs/ReleaseNotes.rst clang/include/clang/Basic/DiagnosticSemaKinds.td clang/lib/Sema/SemaDecl.cpp clang/test/SemaCXX/attr-lifetimebound.cpp Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index 9e1558d8acc99f..170c4cc280537f 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -133,6 +133,15 @@ C++ Specific Potentially Breaking Changes // Fixed version: unsigned operator""_udl_name(unsigned long long); +- Clang will now produce an error diagnostic when [[clang::lifetimebound]] is + applied on a parameter of a function that returns void. This was previously + ignored and had no effect. (#GH107556) + + .. code-block:: c++ + + // Now diagnoses with an error. + void f(int& i [[clang::lifetimebound]]); + ABI Changes in This Version --------------------------- diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td index 8e4718008ece72..9b9bdd7c800e37 100644 --- a/clang/include/clang/Basic/DiagnosticSemaKinds.td +++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td @@ -10097,6 +10097,9 @@ def err_lifetimebound_no_object_param : Error< def err_lifetimebound_ctor_dtor : Error< "'lifetimebound' attribute cannot be applied to a " "%select{constructor|destructor}0">; +def err_lifetimebound_void_return_type : Error< + "'lifetimebound' attribute cannot be applied to a parameter of a function " + "that returns void">; // CHECK: returning address/reference of stack memory def warn_ret_stack_addr_ref : Warning< diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp index 25061f02c13f6c..f8e5f3c6d309d6 100644 --- a/clang/lib/Sema/SemaDecl.cpp +++ b/clang/lib/Sema/SemaDecl.cpp @@ -6940,7 +6940,7 @@ static void checkAttributesAfterMerging(Sema &S, NamedDecl &ND) { } } - // Check the attributes on the function type, if any. + // Check the attributes on the function type and function params, if any. if (const auto *FD = dyn_cast<FunctionDecl>(&ND)) { // Don't declare this variable in the second operand of the for-statement; // GCC miscompiles that by ending its lifetime before evaluating the @@ -6970,6 +6970,18 @@ static void checkAttributesAfterMerging(Sema &S, NamedDecl &ND) { } } } + + for (unsigned int I = 0; I < FD->getNumParams(); ++I) { + const ParmVarDecl *P = FD->getParamDecl(I); + + // The [[lifetimebound]] attribute can be applied to a function parameter + // only if the function returns a value. + if (auto *A = P->getAttr<LifetimeBoundAttr>()) { + if (!isa<CXXConstructorDecl>(FD) && FD->getReturnType()->isVoidType()) { + S.Diag(A->getLocation(), diag::err_lifetimebound_void_return_type); + } + } + } } } diff --git a/clang/test/SemaCXX/attr-lifetimebound.cpp b/clang/test/SemaCXX/attr-lifetimebound.cpp index 1c5c79777c71c8..804d61fb62ca40 100644 --- a/clang/test/SemaCXX/attr-lifetimebound.cpp +++ b/clang/test/SemaCXX/attr-lifetimebound.cpp @@ -1,8 +1,7 @@ // RUN: %clang_cc1 -std=c++23 -verify %s namespace usage_invalid { - // FIXME: Should we diagnose a void return type? - void voidreturn(int ¶m [[clang::lifetimebound]]); + void void_return(int ¶m [[clang::lifetimebound]]); // expected-error {{'lifetimebound' attribute cannot be applied to a parameter of a function that returns void}} int *not_class_member() [[clang::lifetimebound]]; // expected-error {{non-member function has no implicit object parameter}} struct A { @@ -12,6 +11,8 @@ namespace usage_invalid { int *explicit_object(this A&) [[clang::lifetimebound]]; // expected-error {{explicit object member function has no implicit object parameter}} int not_function [[clang::lifetimebound]]; // expected-error {{only applies to parameters and implicit object parameters}} int [[clang::lifetimebound]] also_not_function; // expected-error {{cannot be applied to types}} + // FIXME: Should diagnose a void return type. + void void_return_member() [[clang::lifetimebound]]; }; int *attr_with_param(int ¶m [[clang::lifetimebound(42)]]); // expected-error {{takes no arguments}} } @@ -31,6 +32,13 @@ namespace usage_ok { return *(int*)param; } + template <class T, class R = void> R dependent_void(const T& t [[clang::lifetimebound]]); + void dependent_void_instantiation() { + dependent_void<int>(1); // OK: Returns void. + int x = dependent_void<int, int>(1); // expected-warning {{temporary whose address is used as value of local variable 'x' will be destroyed at the end of the full-expression}} + dependent_void<int, int>(1); // OK: Returns an unused value. + } + struct A { A(); A(int); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
