https://github.com/jhuber6 created
https://github.com/llvm/llvm-project/pull/129917
Summary:
The `-Wglobal-constructors` option is useful for restricting the usage
of global constructors / destructors. However, it currently ignores the
attributes that introduce global constructors, meaning that the module
can still have ctors if `-Werror` is set. If this is intentional by the
user, I believe it would be more correct to push the diagnostic.
>From 58e9c848c648b919c7ea3500f6928b7474f7e582 Mon Sep 17 00:00:00 2001
From: Joseph Huber <hube...@outlook.com>
Date: Wed, 5 Mar 2025 13:27:19 -0600
Subject: [PATCH] [Clang] Make '-Wglobal-constructors` work on the GNU
attributes
Summary:
The `-Wglobal-constructors` option is useful for restricting the usage
of global constructors / destructors. However, it currently ignores the
attributes that introduce global constructors, meaning that the module
can still have ctors if `-Werror` is set. If this is intentional by the
user, I believe it would be more correct to push the diagnostic.
---
clang/lib/Sema/SemaDeclAttr.cpp | 12 ++++++++++++
.../SemaCXX/attr-require-constant-initialization.cpp | 5 +++++
2 files changed, 17 insertions(+)
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index fdf3b9c636127..9daa47c533ad2 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -7596,6 +7596,18 @@ void Sema::ProcessDeclAttributeList(
D->setInvalidDecl();
}
+ // Warn on global constructors and destructors created by attributes.
+ if (D->hasAttr<ConstructorAttr>() &&
+ !getDiagnostics().isIgnored(diag::warn_global_constructor,
+ D->getLocation()))
+ Diag(D->getLocation(), diag::warn_global_constructor)
+ << D->getSourceRange();
+ if (D->hasAttr<DestructorAttr>() &&
+ !getDiagnostics().isIgnored(diag::warn_global_destructor,
+ D->getLocation()))
+ Diag(D->getLocation(), diag::warn_global_destructor)
+ << D->getSourceRange();
+
// Do this check after processing D's attributes because the attribute
// objc_method_family can change whether the given method is in the init
// family, and it can be applied after objc_designated_initializer. This is a
diff --git a/clang/test/SemaCXX/attr-require-constant-initialization.cpp
b/clang/test/SemaCXX/attr-require-constant-initialization.cpp
index 4c0a834551715..b1736ea7a3ebe 100644
--- a/clang/test/SemaCXX/attr-require-constant-initialization.cpp
+++ b/clang/test/SemaCXX/attr-require-constant-initialization.cpp
@@ -337,6 +337,11 @@ constexpr TestCtor<NotC> inval_constexpr(42); //
expected-error {{must be initia
ATTR constexpr TestCtor<NotC> inval_constexpr2(42); // expected-error {{must
be initialized by a constant expression}}
// expected-note@-1 {{in call to 'TestCtor(42)'}}
+[[gnu::constructor]] void ctor() {}
+// expected-warning@-1 {{declaration requires a global constructor}}
+[[gnu::destructor]] void dtor() {}
+// expected-warning@-1 {{declaration requires a global destructor}}
+
#elif defined(TEST_THREE)
#if defined(__cplusplus)
#error This test requires C
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