[clang] [clang] Output a warning when [[lifetimebound]] attribute is applied on a function parameter while the function returns void (PR #113460)
Boaz Brickner via cfe-commits
cfe-commits at lists.llvm.org
Wed Oct 23 06:53:52 PDT 2024
https://github.com/bricknerb created https://github.com/llvm/llvm-project/pull/113460
Fixes: https://github.com/llvm/llvm-project/issues/107556
>From 4405d652029081cd63094e9a81dfa31e8611aad4 Mon Sep 17 00:00:00 2001
From: Boaz Brickner <brickner at google.com>
Date: Wed, 23 Oct 2024 15:50:43 +0200
Subject: [PATCH] [clang] Output a warning when [[lifetimebound]] attribute is
applied on a function parameter while the function returns void.
---
clang/include/clang/Basic/DiagnosticSemaKinds.td | 3 +++
clang/lib/Sema/SemaDecl.cpp | 14 +++++++++++++-
clang/test/SemaCXX/attr-lifetimebound.cpp | 3 +--
3 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 8e4718008ece72..a1c20b22e736ed 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; did you mean 'lifetime_capture_by(X)'">;
// 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 229c9080d558ec..e611bf60718bc5 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..f790559b6b4769 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 voidreturn(int ¶m [[clang::lifetimebound]]); // expected-error {{'lifetimebound' attribute cannot be applied to a parameter of a function that returns void; did you mean 'lifetime_capture_by(X)'}}
int *not_class_member() [[clang::lifetimebound]]; // expected-error {{non-member function has no implicit object parameter}}
struct A {
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