https://github.com/mahtohappy created
https://github.com/llvm/llvm-project/pull/81225
For templates, isDependentContext() is true, that's why the previous if check
was failing.
Here, we traverse the RD and upon finding a Union declaration we check if at
least one member of the union is initialized.
If not, it produces a diagnosis for it.
Fix #46689
>From aeb0686c76f2745111acd92c0d6b77faf69d2ed6 Mon Sep 17 00:00:00 2001
From: mahtohappy <happy.ku...@windriver.com>
Date: Thu, 8 Feb 2024 10:51:22 -0800
Subject: [PATCH 1/2] [Clang][Sema] Diagnosis for constexpr constructor not
initializing a union member
---
clang/docs/ReleaseNotes.rst | 5 +-
clang/lib/Sema/SemaDeclCXX.cpp | 47 ++++++++++++++-----
.../CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp | 3 ++
.../SemaCXX/constexpr-union-temp-ctor-cxx.cpp | 27 +++++++++++
4 files changed, 69 insertions(+), 13 deletions(-)
create mode 100644 clang/test/SemaCXX/constexpr-union-temp-ctor-cxx.cpp
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 32440ee64e3ebe..0072495354b8eb 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -149,9 +149,10 @@ Improvements to Clang's diagnostics
prints.
- Clang now diagnoses member template declarations with multiple declarators.
+- Clang now diagnoses use of the ``template`` keyword after declarative nested
name specifiers.
-- Clang now diagnoses use of the ``template`` keyword after declarative nested
- name specifiers.
+- Clang now diagnoses constexpr constructor for not initializing atleast one
member of union
+- Fixes(`#46689 Constexpr constructor not initializing a union member is not
diagnosed`)
- The ``-Wshorten-64-to-32`` diagnostic is now grouped under
``-Wimplicit-int-conversion`` instead
of ``-Wconversion``. Fixes `#69444
<https://github.com/llvm/llvm-project/issues/69444>`_.
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index fea8c5036c80b1..8da4f095765661 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -1795,6 +1795,11 @@ static bool CheckConstexprFunctionBody(Sema &SemaRef,
const FunctionDecl *Dcl,
Stmt *Body,
Sema::CheckConstexprKind Kind);
+static bool checkUnionConstructorIntializer(Sema &SemaRef, const FunctionDecl
*Dcl,
+ const CXXConstructorDecl *Constructor,
+ const CXXRecordDecl *RD,
+ Sema::CheckConstexprKind Kind);
+
// Check whether a function declaration satisfies the requirements of a
// constexpr function definition or a constexpr constructor definition. If so,
// return true. If not, produce appropriate diagnostics (unless asked not to by
@@ -2343,17 +2348,9 @@ static bool CheckConstexprFunctionBody(Sema &SemaRef,
const FunctionDecl *Dcl,
// - if the class is a union having variant members, exactly one of them
// shall be initialized;
if (RD->isUnion()) {
- if (Constructor->getNumCtorInitializers() == 0 &&
- RD->hasVariantMembers()) {
- if (Kind == Sema::CheckConstexprKind::Diagnose) {
- SemaRef.Diag(
- Dcl->getLocation(),
- SemaRef.getLangOpts().CPlusPlus20
- ? diag::warn_cxx17_compat_constexpr_union_ctor_no_init
- : diag::ext_constexpr_union_ctor_no_init);
- } else if (!SemaRef.getLangOpts().CPlusPlus20) {
- return false;
- }
+ if (checkUnionConstructorIntializer(SemaRef, Dcl, Constructor, RD,
+ Kind)) {
+ return false;
}
} else if (!Constructor->isDependentContext() &&
!Constructor->isDelegatingConstructor()) {
@@ -2393,6 +2390,17 @@ static bool CheckConstexprFunctionBody(Sema &SemaRef,
const FunctionDecl *Dcl,
Kind))
return false;
}
+ } else if (!Constructor->isDelegatingConstructor()) {
+ for (const Decl *Decls : RD->decls()) {
+ if (const auto *Inner = dyn_cast<CXXRecordDecl>(Decls)) {
+ if (Inner->isUnion()) {
+ if (checkUnionConstructorIntializer(SemaRef, Dcl, Constructor,
+ Inner, Kind)) {
+ return true;
+ }
+ }
+ }
+ }
}
} else {
if (ReturnStmts.empty()) {
@@ -2471,6 +2479,23 @@ static bool CheckConstexprFunctionBody(Sema &SemaRef,
const FunctionDecl *Dcl,
return true;
}
+static bool
+checkUnionConstructorIntializer(Sema &SemaRef, const FunctionDecl *Dcl,
+ const CXXConstructorDecl *Constructor,
+ const CXXRecordDecl *RD,
+ Sema::CheckConstexprKind Kind) {
+ if (Constructor->getNumCtorInitializers() == 0 && RD->hasVariantMembers()) {
+ if (Kind == Sema::CheckConstexprKind::Diagnose) {
+ SemaRef.Diag(Dcl->getLocation(),
+ SemaRef.getLangOpts().CPlusPlus20
+ ? diag::warn_cxx17_compat_constexpr_union_ctor_no_init
+ : diag::ext_constexpr_union_ctor_no_init);
+ } else if (!SemaRef.getLangOpts().CPlusPlus20) {
+ return true;
+ }
+ }
+ return false;
+}
bool Sema::CheckImmediateEscalatingFunctionDefinition(
FunctionDecl *FD, const sema::FunctionScopeInfo *FSI) {
if (!getLangOpts().CPlusPlus20 || !FD->isImmediateEscalating())
diff --git a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
index f1f677ebfcd341..37c9e2c36ad657 100644
--- a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
+++ b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
@@ -224,6 +224,9 @@ struct TemplateInit {
};
// FIXME: This is ill-formed (no diagnostic required). We should diagnose it.
constexpr TemplateInit() {} // desired-error {{must initialize all members}}
+#ifndef CXX2A
+ // expected-error@-2 {{constexpr union constructor that does not initialize
any member is a C++20 extension}}
+#endif
};
template<typename T> struct TemplateInit2 {
Literal l;
diff --git a/clang/test/SemaCXX/constexpr-union-temp-ctor-cxx.cpp
b/clang/test/SemaCXX/constexpr-union-temp-ctor-cxx.cpp
new file mode 100644
index 00000000000000..51d5e1d8cf9341
--- /dev/null
+++ b/clang/test/SemaCXX/constexpr-union-temp-ctor-cxx.cpp
@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -std=c++14 -verify -fcxx-exceptions
-Werror=c++14-extensions -Werror=c++20-extensions %s
+
+template <class> struct C {
+ union {
+ int i;
+ };
+ constexpr C() {} // expected-error {{constexpr union constructor that does
not initialize any member is a C++20 extension}}
+};
+constexpr C<int> c;
+
+template <class> class D {
+ union {
+ int i;
+ };
+public:
+ constexpr D() {} // expected-error {{constexpr union constructor that does
not initialize any member is a C++20 extension}}
+};
+constexpr D<int> d;
+
+template<typename T>
+struct Foo {
+ union {
+ int i;
+ };
+ constexpr Foo(int a): i(a){}
+};
+constexpr Foo<int> f(5);
>From 50914b46d2360915d2a88de99fa6b7eb28197c99 Mon Sep 17 00:00:00 2001
From: mahtohappy <happy.ku...@windriver.com>
Date: Thu, 8 Feb 2024 10:51:22 -0800
Subject: [PATCH 2/2] [Clang][Sema] Diagnosis for constexpr constructor not
initializing a union member
---
clang/lib/Sema/SemaDeclCXX.cpp | 9 +++++----
clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp | 3 +--
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 8da4f095765661..f6c7410e3be92a 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -1795,10 +1795,11 @@ static bool CheckConstexprFunctionBody(Sema &SemaRef,
const FunctionDecl *Dcl,
Stmt *Body,
Sema::CheckConstexprKind Kind);
-static bool checkUnionConstructorIntializer(Sema &SemaRef, const FunctionDecl
*Dcl,
- const CXXConstructorDecl *Constructor,
- const CXXRecordDecl *RD,
- Sema::CheckConstexprKind Kind);
+static bool
+checkUnionConstructorIntializer(Sema &SemaRef, const FunctionDecl *Dcl,
+ const CXXConstructorDecl *Constructor,
+ const CXXRecordDecl *RD,
+ Sema::CheckConstexprKind Kind);
// Check whether a function declaration satisfies the requirements of a
// constexpr function definition or a constexpr constructor definition. If so,
diff --git a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
index 37c9e2c36ad657..a4434d1c35943f 100644
--- a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
+++ b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
@@ -222,8 +222,7 @@ struct TemplateInit {
T g;
T h;
};
- // FIXME: This is ill-formed (no diagnostic required). We should diagnose it.
- constexpr TemplateInit() {} // desired-error {{must initialize all members}}
+ constexpr TemplateInit() {}
#ifndef CXX2A
// expected-error@-2 {{constexpr union constructor that does not initialize
any member is a C++20 extension}}
#endif
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