[clang] af34ac4 - [Clang] [Sema] No longer diagnose type definitions in `offsetof` in C23 mode (#84169)
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Fri Mar 29 09:42:13 PDT 2024
Author: Sirraide
Date: 2024-03-29T17:42:09+01:00
New Revision: af34ac4508adcb5b54e62947d7caf7dd40227b16
URL: https://github.com/llvm/llvm-project/commit/af34ac4508adcb5b54e62947d7caf7dd40227b16
DIFF: https://github.com/llvm/llvm-project/commit/af34ac4508adcb5b54e62947d7caf7dd40227b16.diff
LOG: [Clang] [Sema] No longer diagnose type definitions in `offsetof` in C23 mode (#84169)
This is now allowed in C23; continue to diagnose it in earlier language
modes as before, but now as a C23 extension rather than a GNU extension.
This fixes #83658.
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDecl.cpp
clang/test/C/C2x/n2350.c
clang/test/C/drs/dr4xx.c
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index c193c20fae5cf0..37b843915a0dee 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -307,6 +307,9 @@ Improvements to Clang's diagnostics
- ``-Wmicrosoft``, ``-Wgnu``, or ``-pedantic`` is now required to diagnose C99
flexible array members in a union or alone in a struct. Fixes GH#84565.
+- Clang now no longer diagnoses type definitions in ``offsetof`` in C23 mode.
+ Fixes #GH83658.
+
Improvements to Clang's time-trace
----------------------------------
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 51af81bf1f6fc5..fbc9c04dfba939 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1748,8 +1748,8 @@ def err_type_defined_in_condition : Error<
def err_type_defined_in_enum : Error<
"%0 cannot be defined in an enumeration">;
def ext_type_defined_in_offsetof : Extension<
- "defining a type within '%select{__builtin_offsetof|offsetof}0' is a Clang "
- "extension">, InGroup<GNUOffsetofExtensions>;
+ "defining a type within '%select{__builtin_offsetof|offsetof}0' is a C23 "
+ "extension">, InGroup<C23>;
def note_pure_virtual_function : Note<
"unimplemented pure virtual method %0 in %1">;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 503f1f6f53a258..5027deda0d7e09 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -18170,7 +18170,9 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
cast_or_null<RecordDecl>(PrevDecl));
}
- if (OOK != OOK_Outside && TUK == TUK_Definition && !getLangOpts().CPlusPlus)
+ // Only C23 and later allow defining new types in 'offsetof()'.
+ if (OOK != OOK_Outside && TUK == TUK_Definition && !getLangOpts().CPlusPlus &&
+ !getLangOpts().C23)
Diag(New->getLocation(), diag::ext_type_defined_in_offsetof)
<< (OOK == OOK_Macro) << New->getSourceRange();
diff --git a/clang/test/C/C2x/n2350.c b/clang/test/C/C2x/n2350.c
index 2f738488a37427..af0ca6d79be5e1 100644
--- a/clang/test/C/C2x/n2350.c
+++ b/clang/test/C/C2x/n2350.c
@@ -5,7 +5,7 @@
// RUN: %clang_cc1 -fsyntax-only -pedantic -Wno-comment -std=c99 -verify %s
// RUN: %clang_cc1 -fsyntax-only -pedantic -Wno-comment -std=c11 -verify %s
// RUN: %clang_cc1 -fsyntax-only -pedantic -Wno-comment -std=c17 -verify %s
-// RUN: %clang_cc1 -fsyntax-only -pedantic -Wno-comment -std=c2x -verify %s
+// RUN: %clang_cc1 -fsyntax-only -pedantic -Wno-comment -std=c2x -verify=silent %s
// silent-no-diagnostics
@@ -13,10 +13,10 @@
// https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm
int simple(void) {
return __builtin_offsetof(struct A // cpp-error {{'A' cannot be defined in a type specifier}} \
- expected-warning {{defining a type within '__builtin_offsetof' is a Clang extension}}
+ expected-warning {{defining a type within '__builtin_offsetof' is a C23 extension}}
{
int a;
- struct B // expected-warning {{defining a type within '__builtin_offsetof' is a Clang extension}}
+ struct B // expected-warning {{defining a type within '__builtin_offsetof' is a C23 extension}}
{
int c;
int d;
@@ -26,7 +26,7 @@ int simple(void) {
int anonymous_struct(void) {
return __builtin_offsetof(struct // cpp-error-re {{'(unnamed struct at {{.*}})' cannot be defined in a type specifier}} \
- expected-warning {{defining a type within '__builtin_offsetof' is a Clang extension}}
+ expected-warning {{defining a type within '__builtin_offsetof' is a C23 extension}}
{
int a;
int b;
@@ -47,7 +47,7 @@ int struct_in_second_param(void) {
int macro(void) {
return offsetof(struct A // cpp-error {{'A' cannot be defined in a type specifier}} \
- expected-warning 2 {{defining a type within 'offsetof' is a Clang extension}}
+ expected-warning 2 {{defining a type within 'offsetof' is a C23 extension}}
{
int a;
struct B // verifier seems to think the error is emitted by the macro
diff --git a/clang/test/C/drs/dr4xx.c b/clang/test/C/drs/dr4xx.c
index 30145dcfeef168..83d7b94cd67959 100644
--- a/clang/test/C/drs/dr4xx.c
+++ b/clang/test/C/drs/dr4xx.c
@@ -1,7 +1,7 @@
-/* RUN: %clang_cc1 -std=c89 -verify=expected,c89only -pedantic -Wno-c11-extensions %s
- RUN: %clang_cc1 -std=c99 -verify=expected -pedantic -Wno-c11-extensions %s
- RUN: %clang_cc1 -std=c11 -verify=expected -pedantic %s
- RUN: %clang_cc1 -std=c17 -verify=expected -pedantic %s
+/* RUN: %clang_cc1 -std=c89 -verify=expected,c89only,pre-c23 -pedantic -Wno-c11-extensions %s
+ RUN: %clang_cc1 -std=c99 -verify=expected,pre-c23 -pedantic -Wno-c11-extensions %s
+ RUN: %clang_cc1 -std=c11 -verify=expected,pre-c23 -pedantic %s
+ RUN: %clang_cc1 -std=c17 -verify=expected,pre-c23 -pedantic %s
RUN: %clang_cc1 -std=c2x -verify=expected -pedantic %s
*/
@@ -343,10 +343,13 @@ void dr496(void) {
*/
/* The DR asked a question about whether defining a new type within offsetof
- * is allowed. C2x N2350 made this explicitly undefined behavior, but GCC and
- * Clang both support it as an extension.
+ * is allowed. C23 N2350 had made this explicitly undefined behavior, but this
+ * was later overturned when C23 DE-137 was accepted, making it well-formed.
+ *
+ * Additionally, GCC and Clang both support it as an extension in pre-C23
+ * mode.
*/
- (void)__builtin_offsetof(struct S { int a; }, a); /* expected-warning{{defining a type within '__builtin_offsetof' is a Clang extension}} */
+ (void)__builtin_offsetof(struct S { int a; }, a); /* pre-c23-warning{{defining a type within '__builtin_offsetof' is a C23 extension}} */
}
/* WG14 DR499: yes
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