[clang] [Clang] Fix missing diagnostic for non-standard layout type in `offsetof` (PR #65246)

via cfe-commits cfe-commits at lists.llvm.org
Sun Oct 1 17:57:19 PDT 2023


https://github.com/kasuga-fj updated https://github.com/llvm/llvm-project/pull/65246

>From 7d59f47b9b18ee5db90bb9fd69a1f73f68569ae4 Mon Sep 17 00:00:00 2001
From: "kasuga.ryotaro" <kasuga.ryotaro at fujitsu.com>
Date: Wed, 30 Aug 2023 13:26:31 +0900
Subject: [PATCH 01/10] [Clang] Fix missing diagnostic for non-standard layout
 type in `offsetof`

Fixes #64619

Clang warns diagnostic for non-standard layout types in `offsetof` only
if they are in evaluated context. With this patch, you'll also get
  diagnostic if you use `offsetof` on non-standard layout types in any
  other contexts
---
 clang/lib/Sema/SemaExpr.cpp         |  9 ++++-----
 clang/test/SemaCXX/class-layout.cpp | 30 ++++++++++++++---------------
 clang/test/SemaCXX/ms_struct.cpp    |  5 ++---
 clang/test/SemaCXX/offsetof.cpp     | 10 +++++-----
 4 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 92496b03ecabe54..6537b085aa46c5b 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -16766,12 +16766,11 @@ ExprResult Sema::BuildBuiltinOffsetOf(SourceLocation BuiltinLoc,
         LangOpts.CPlusPlus11? diag::ext_offsetof_non_standardlayout_type
                             : diag::ext_offsetof_non_pod_type;
 
-      if (!IsSafe && !DidWarnAboutNonPOD &&
-          DiagRuntimeBehavior(BuiltinLoc, nullptr,
-                              PDiag(DiagID)
-                              << SourceRange(Components[0].LocStart, OC.LocEnd)
-                              << CurrentType))
+      if (!IsSafe && !DidWarnAboutNonPOD) {
+        Diag(BuiltinLoc, DiagID)
+            << SourceRange(Components[0].LocStart, OC.LocEnd) << CurrentType;
         DidWarnAboutNonPOD = true;
+      }
     }
 
     // Look for the field.
diff --git a/clang/test/SemaCXX/class-layout.cpp b/clang/test/SemaCXX/class-layout.cpp
index 9782ff08100b2d6..23b3dbe24249378 100644
--- a/clang/test/SemaCXX/class-layout.cpp
+++ b/clang/test/SemaCXX/class-layout.cpp
@@ -1,18 +1,18 @@
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++98 -Wno-inaccessible-base -Wno-c++11-extensions
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base
-// RUN: %clang_cc1 -triple x86_64-apple-darwin    %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
-// RUN: %clang_cc1 -triple x86_64-scei-ps4        %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
-// RUN: %clang_cc1 -triple x86_64-sie-ps5         %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=6
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=6 -DCLANG_ABI_COMPAT=6
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
-// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=16 -DCLANG_ABI_COMPAT=16
-// RUN: %clang_cc1 -triple powerpc-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
-// RUN: %clang_cc1 -triple powerpc-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
-// RUN: %clang_cc1 -triple powerpc64-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -DCLANG_ABI_COMPAT=15
-// RUN: %clang_cc1 -triple powerpc64-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
-// RUN: %clang_cc1 -triple s390x-none-zos %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base
-// RUN: %clang_cc1 -triple s390x-none-zos %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++98 -Wno-inaccessible-base -Wno-invalid-offsetof -Wno-c++11-extensions
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof
+// RUN: %clang_cc1 -triple x86_64-apple-darwin    %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -triple x86_64-scei-ps4        %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -DCLANG_ABI_COMPAT=6
+// RUN: %clang_cc1 -triple x86_64-sie-ps5         %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -DCLANG_ABI_COMPAT=6
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -fclang-abi-compat=6 -DCLANG_ABI_COMPAT=6
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -fclang-abi-compat=16 -DCLANG_ABI_COMPAT=16
+// RUN: %clang_cc1 -triple powerpc-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -triple powerpc-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -triple powerpc64-ibm-aix7.3.0.0 %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
+// RUN: %clang_cc1 -triple s390x-none-zos %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof
+// RUN: %clang_cc1 -triple s390x-none-zos %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base -Wno-invalid-offsetof -fclang-abi-compat=15 -DCLANG_ABI_COMPAT=15
 
 // RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++98 -Wno-inaccessible-base -Wno-c++11-extensions
 // RUN: %clang_cc1 -fexperimental-new-constant-interpreter -triple x86_64-unknown-unknown %s -fsyntax-only -verify -std=c++11 -Wno-inaccessible-base
diff --git a/clang/test/SemaCXX/ms_struct.cpp b/clang/test/SemaCXX/ms_struct.cpp
index e6f0a25b38ea80c..0d1a3d5259475d9 100644
--- a/clang/test/SemaCXX/ms_struct.cpp
+++ b/clang/test/SemaCXX/ms_struct.cpp
@@ -25,6 +25,7 @@ struct B : public A {
 
 static_assert(__builtin_offsetof(B, d) == 12,
   "We can't allocate the bitfield into the padding under ms_struct");
+// expected-warning at -2 {{offset of on non-standard-layout type 'B'}}
 
 struct C {
 #ifdef TEST_FOR_ERROR
@@ -38,6 +39,4 @@ struct C {
 
 static_assert(__builtin_offsetof(C, n) == 8,
               "long long field in ms_struct should be 8-byte aligned");
-#if !defined(TEST_FOR_ERROR) && !defined(TEST_FOR_WARNING)
-// expected-no-diagnostics
-#endif
+// expected-warning at -2 {{offset of on non-standard-layout type 'C'}}
\ No newline at end of file
diff --git a/clang/test/SemaCXX/offsetof.cpp b/clang/test/SemaCXX/offsetof.cpp
index c984657ebe1f0ed..a1e42d3d6802ff3 100644
--- a/clang/test/SemaCXX/offsetof.cpp
+++ b/clang/test/SemaCXX/offsetof.cpp
@@ -18,7 +18,7 @@ struct Base { int x; };
 struct Derived : Base { int y; };
 int o = __builtin_offsetof(Derived, x); // expected-warning{{offset of on non-POD type}}
 
-const int o2 = sizeof(__builtin_offsetof(Derived, x));
+const int o2 = sizeof(__builtin_offsetof(Derived, x)); // expected-warning{{offset of on non-POD type 'Derived'}}
 
 struct HasArray {
   int array[17];
@@ -51,9 +51,9 @@ struct Derived2 : public Base1, public Base2 {
   int z; 
 };
 
-int derived1[__builtin_offsetof(Derived2, x) == 0? 1 : -1];
-int derived2[__builtin_offsetof(Derived2, y)  == 4? 1 : -1];
-int derived3[__builtin_offsetof(Derived2, z)  == 8? 1 : -1];
+int derived1[__builtin_offsetof(Derived2, x) == 0? 1 : -1]; // expected-warning{{offset of on non-POD type 'Derived2'}}
+int derived2[__builtin_offsetof(Derived2, y)  == 4? 1 : -1]; // expected-warning{{offset of on non-POD type 'Derived2'}}
+int derived3[__builtin_offsetof(Derived2, z)  == 8? 1 : -1]; // expected-warning{{offset of on non-POD type 'Derived2'}}
 
 // offsetof referring to anonymous struct in base.
 // PR7769
@@ -66,7 +66,7 @@ struct foo {
 struct bar : public foo  {
 };
 
-int anonstruct[__builtin_offsetof(bar, x) == 0 ? 1 : -1];
+int anonstruct[__builtin_offsetof(bar, x) == 0 ? 1 : -1]; // expected-warning{{offset of on non-POD type 'bar'}}
 
 struct LtoRCheck {
   int a[10];

>From e44041dc1ce0c9f75aba64560c8cfd5e1fe5ee88 Mon Sep 17 00:00:00 2001
From: "kasuga.ryotaro" <kasuga.ryotaro at fujitsu.com>
Date: Mon, 4 Sep 2023 16:06:56 +0900
Subject: [PATCH 02/10] fixup! [Clang] Fix missing diagnostic for non-standard
 layout type in `offsetof`

---
 clang/docs/ReleaseNotes.rst | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 8f5a67e14c9aba3..09497adbafb68d6 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -208,6 +208,8 @@ Improvements to Clang's diagnostics
   (`#54678: <https://github.com/llvm/llvm-project/issues/54678>`_).
 - Clang now prints its 'note' diagnostic in cyan instead of black, to be more compatible
   with terminals with dark background colors. This is also more consistent with GCC.
+- Clang now always diagnoses when using non-standard layout types in ``offsetof`` .
+  (`#64619: <https://github.com/llvm/llvm-project/issues/64619>`_)
 
 Bug Fixes in This Version
 -------------------------

>From 8402bf31bc257b8b3521aeafab554177ed30e27a Mon Sep 17 00:00:00 2001
From: "kasuga.ryotaro" <kasuga.ryotaro at fujitsu.com>
Date: Mon, 4 Sep 2023 18:22:06 +0900
Subject: [PATCH 03/10] fixup! [Clang] Fix missing diagnostic for non-standard
 layout type in `offsetof`

---
 clang/test/SemaCXX/ms_struct.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/clang/test/SemaCXX/ms_struct.cpp b/clang/test/SemaCXX/ms_struct.cpp
index 0d1a3d5259475d9..995e424d1f87640 100644
--- a/clang/test/SemaCXX/ms_struct.cpp
+++ b/clang/test/SemaCXX/ms_struct.cpp
@@ -39,4 +39,5 @@ struct C {
 
 static_assert(__builtin_offsetof(C, n) == 8,
               "long long field in ms_struct should be 8-byte aligned");
-// expected-warning at -2 {{offset of on non-standard-layout type 'C'}}
\ No newline at end of file
+// expected-warning at -2 {{offset of on non-standard-layout type 'C'}}
+

>From b2dfb9f3c7aa681de631f3f33b19f470601bea49 Mon Sep 17 00:00:00 2001
From: "kasuga.ryotaro" <kasuga.ryotaro at fujitsu.com>
Date: Tue, 5 Sep 2023 13:39:12 +0900
Subject: [PATCH 05/10] fixup! [Clang] Fix missing diagnostic for non-standard
 layout type in `offsetof`

---
 clang/test/SemaCXX/offsetof.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/test/SemaCXX/offsetof.cpp b/clang/test/SemaCXX/offsetof.cpp
index a1e42d3d6802ff3..bf8a064859915b8 100644
--- a/clang/test/SemaCXX/offsetof.cpp
+++ b/clang/test/SemaCXX/offsetof.cpp
@@ -68,6 +68,7 @@ struct bar : public foo  {
 
 int anonstruct[__builtin_offsetof(bar, x) == 0 ? 1 : -1]; // expected-warning{{offset of on non-POD type 'bar'}}
 
+
 struct LtoRCheck {
   int a[10];
   int f();

>From 894b3f96d3fa9ec20e2c8e1f23914f521cde51a0 Mon Sep 17 00:00:00 2001
From: "kasuga.ryotaro" <kasuga.ryotaro at fujitsu.com>
Date: Wed, 6 Sep 2023 10:23:56 +0900
Subject: [PATCH 06/10] fixup! [Clang] Fix missing diagnostic for non-standard
 layout type in `offsetof`

---
 clang/lib/Sema/SemaExpr.cpp     | 2 +-
 clang/test/SemaCXX/offsetof.cpp | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 6537b085aa46c5b..fedea932c5e15fe 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -16766,7 +16766,7 @@ ExprResult Sema::BuildBuiltinOffsetOf(SourceLocation BuiltinLoc,
         LangOpts.CPlusPlus11? diag::ext_offsetof_non_standardlayout_type
                             : diag::ext_offsetof_non_pod_type;
 
-      if (!IsSafe && !DidWarnAboutNonPOD) {
+      if (!IsSafe && !DidWarnAboutNonPOD && !isUnevaluatedContext()) {
         Diag(BuiltinLoc, DiagID)
             << SourceRange(Components[0].LocStart, OC.LocEnd) << CurrentType;
         DidWarnAboutNonPOD = true;
diff --git a/clang/test/SemaCXX/offsetof.cpp b/clang/test/SemaCXX/offsetof.cpp
index bf8a064859915b8..c4e86369f007dcb 100644
--- a/clang/test/SemaCXX/offsetof.cpp
+++ b/clang/test/SemaCXX/offsetof.cpp
@@ -18,7 +18,7 @@ struct Base { int x; };
 struct Derived : Base { int y; };
 int o = __builtin_offsetof(Derived, x); // expected-warning{{offset of on non-POD type}}
 
-const int o2 = sizeof(__builtin_offsetof(Derived, x)); // expected-warning{{offset of on non-POD type 'Derived'}}
+const int o2 = sizeof(__builtin_offsetof(Derived, x));
 
 struct HasArray {
   int array[17];

>From 67df2b7ba361cc724a70d8f8b140abbc27bc8e24 Mon Sep 17 00:00:00 2001
From: kasuga-fj <kasuga.ryotaro at fujitsu.com>
Date: Thu, 28 Sep 2023 18:10:15 +0900
Subject: [PATCH 07/10] fixup! [Clang] Fix missing diagnostic for non-standard
 layout type in `offsetof`

---
 libcxx/include/__type_traits/datasizeof.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libcxx/include/__type_traits/datasizeof.h b/libcxx/include/__type_traits/datasizeof.h
index 019099a9cf183b5..88a702470c3c15a 100644
--- a/libcxx/include/__type_traits/datasizeof.h
+++ b/libcxx/include/__type_traits/datasizeof.h
@@ -47,7 +47,11 @@ struct __libcpp_datasizeof {
   };
 #endif
 
+  _LIBCPP_DIAGNOSTIC_PUSH
+  _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Winvalid-offsetof")
+  _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Winvalid-offsetof")
   static const size_t value = offsetof(_FirstPaddingByte<>, __first_padding_byte_);
+  _LIBCPP_DIAGNOSTIC_POP
 };
 
 _LIBCPP_END_NAMESPACE_STD

>From bf479bc77e927aaa7a90c765987020ad39c857a5 Mon Sep 17 00:00:00 2001
From: kasuga-fj <kasuga.ryotaro at fujitsu.com>
Date: Fri, 29 Sep 2023 13:04:08 +0900
Subject: [PATCH 08/10] fixup! [Clang] Fix missing diagnostic for non-standard
 layout type in `offsetof`

---
 libcxx/include/__type_traits/datasizeof.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libcxx/include/__type_traits/datasizeof.h b/libcxx/include/__type_traits/datasizeof.h
index 88a702470c3c15a..a28be0e94e5b7ac 100644
--- a/libcxx/include/__type_traits/datasizeof.h
+++ b/libcxx/include/__type_traits/datasizeof.h
@@ -47,6 +47,8 @@ struct __libcpp_datasizeof {
   };
 #endif
 
+  // Disable warnings related to the use of `offsetof` on non-standard layout or non-POD types
+  // TODO : Find a way to replace `offsetof` ?
   _LIBCPP_DIAGNOSTIC_PUSH
   _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Winvalid-offsetof")
   _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Winvalid-offsetof")

>From b9e201a80ee7e79f8ddfe37fee097b8efddc0a8a Mon Sep 17 00:00:00 2001
From: kasuga-fj <143047127+kasuga-fj at users.noreply.github.com>
Date: Mon, 2 Oct 2023 09:52:37 +0900
Subject: [PATCH 09/10] fixup! [Clang] Fix missing diagnostic for non-standard
 layout type in `offsetof`

Co-authored-by: philnik777 <nikolasklauser at berlin.de>
---
 libcxx/include/__type_traits/datasizeof.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcxx/include/__type_traits/datasizeof.h b/libcxx/include/__type_traits/datasizeof.h
index a28be0e94e5b7ac..cfdd8cbbcb982b1 100644
--- a/libcxx/include/__type_traits/datasizeof.h
+++ b/libcxx/include/__type_traits/datasizeof.h
@@ -47,7 +47,7 @@ struct __libcpp_datasizeof {
   };
 #endif
 
-  // Disable warnings related to the use of `offsetof` on non-standard layout or non-POD types
+  // _FirstPaddingByte<> is sometimes non-standard layout. Using `offsetof` is UB in that case, but GCC and Clang allow the use as an extension.
   // TODO : Find a way to replace `offsetof` ?
   _LIBCPP_DIAGNOSTIC_PUSH
   _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Winvalid-offsetof")

>From bceac70fb5514d1c3583e690ec1b2bc3b2ee039c Mon Sep 17 00:00:00 2001
From: kasuga-fj <kasuga.ryotaro at fujitsu.com>
Date: Mon, 2 Oct 2023 09:56:55 +0900
Subject: [PATCH 10/10] fixup! [Clang] Fix missing diagnostic for non-standard
 layout type in `offsetof`

---
 libcxx/include/__type_traits/datasizeof.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/libcxx/include/__type_traits/datasizeof.h b/libcxx/include/__type_traits/datasizeof.h
index cfdd8cbbcb982b1..8795bd7a7c57a86 100644
--- a/libcxx/include/__type_traits/datasizeof.h
+++ b/libcxx/include/__type_traits/datasizeof.h
@@ -48,10 +48,8 @@ struct __libcpp_datasizeof {
 #endif
 
   // _FirstPaddingByte<> is sometimes non-standard layout. Using `offsetof` is UB in that case, but GCC and Clang allow the use as an extension.
-  // TODO : Find a way to replace `offsetof` ?
   _LIBCPP_DIAGNOSTIC_PUSH
   _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Winvalid-offsetof")
-  _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Winvalid-offsetof")
   static const size_t value = offsetof(_FirstPaddingByte<>, __first_padding_byte_);
   _LIBCPP_DIAGNOSTIC_POP
 };



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