aaron.ballman created this revision.
aaron.ballman added reviewers: erichkeane, clang-language-wg, jyknight.
Herald added a project: All.
aaron.ballman requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
This was a mistake from e7300e75b51a7e7d4e81975b4be7a6c65f9a8286
<https://reviews.llvm.org/rGe7300e75b51a7e7d4e81975b4be7a6c65f9a8286>
(https://reviews.llvm.org/D133574) caused by us accidentally tracking an older
copy of the C DR list for DR496. The text in
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2396.htm#dr_496 makes it
clear that subobjects are allowed, which means member and array access
expressions are allowed.
This backs out the changes from the previous commit that relate to this
diagnostic.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D142723
Files:
clang/docs/LanguageExtensions.rst
clang/include/clang/Basic/DiagnosticParseKinds.td
clang/lib/Parse/ParseExpr.cpp
clang/test/C/C2x/n2350.c
clang/test/C/drs/dr4xx.c
clang/test/CXX/drs/dr4xx.cpp
Index: clang/test/CXX/drs/dr4xx.cpp
===================================================================
--- clang/test/CXX/drs/dr4xx.cpp
+++ clang/test/CXX/drs/dr4xx.cpp
@@ -687,9 +687,9 @@
U<__builtin_offsetof(A, n)>::type a;
U<__builtin_offsetof(T, n)>::type b; // expected-error +{{}} expected-warning 0+{{}}
// as an extension, we allow the member-designator to include array indices
- g(__builtin_offsetof(A, a[0])).h<int>(); // expected-error {{using an array subscript expression within '__builtin_offsetof' is a Clang extension}}
- g(__builtin_offsetof(A, a[N])).h<int>(); // expected-error {{using an array subscript expression within '__builtin_offsetof' is a Clang extension}}
- U<__builtin_offsetof(A, a[0])>::type c; // expected-error {{using an array subscript expression within '__builtin_offsetof' is a Clang extension}}
+ g(__builtin_offsetof(A, a[0])).h<int>();
+ g(__builtin_offsetof(A, a[N])).h<int>();
+ U<__builtin_offsetof(A, a[0])>::type c;
U<__builtin_offsetof(A, a[N])>::type d; // expected-error +{{}} expected-warning 0+{{}}
}
}
Index: clang/test/C/drs/dr4xx.c
===================================================================
--- clang/test/C/drs/dr4xx.c
+++ clang/test/C/drs/dr4xx.c
@@ -331,19 +331,13 @@
struct B { struct A a; };
struct C { struct A a[1]; };
- /* The standard does not require either of these examples to work, but we
- * support them just the same. The first one is invalid because it's
- * referencing a member of a different struct, and the second one is invalid
- * because it references an array of another struct. Clang calculates the
- * correct offset to each of those fields.
- */
- _Static_assert(__builtin_offsetof(struct B, a.n) == 0, ""); /* expected-warning {{using a member access expression within '__builtin_offsetof' is a Clang extension}} */
+ /* Array access & member access expressions are now valid. */
+ _Static_assert(__builtin_offsetof(struct B, a.n) == 0, "");
/* First int below is for 'n' and the second int is for 'a[0]'; this presumes
* there is no padding involved.
*/
- _Static_assert(__builtin_offsetof(struct B, a.a[1]) == sizeof(int) + sizeof(int), ""); /* expected-warning {{using a member access expression within '__builtin_offsetof' is a Clang extension}}
- expected-warning {{using an array subscript expression within '__builtin_offsetof' is a Clang extension}}
- */
+ _Static_assert(__builtin_offsetof(struct B, a.a[1]) == sizeof(int) + sizeof(int), "");
+
/* However, we do not support using the -> operator to access a member, even
* if that would be a valid expression. FIXME: GCC accepts this, perhaps we
* should as well.
Index: clang/test/C/C2x/n2350.c
===================================================================
--- clang/test/C/C2x/n2350.c
+++ clang/test/C/C2x/n2350.c
@@ -38,8 +38,7 @@
int a, b;
int x[20];
};
- return __builtin_offsetof(struct A, x[sizeof(struct B{int a;})]); // cpp-error {{'B' cannot be defined in a type specifier}} \
- expected-warning {{using an array subscript expression within '__builtin_offsetof' is a Clang extension}}
+ return __builtin_offsetof(struct A, x[sizeof(struct B{int a;})]); // cpp-error {{'B' cannot be defined in a type specifier}}
}
Index: clang/lib/Parse/ParseExpr.cpp
===================================================================
--- clang/lib/Parse/ParseExpr.cpp
+++ clang/lib/Parse/ParseExpr.cpp
@@ -2629,12 +2629,6 @@
Comps.back().U.IdentInfo = Tok.getIdentifierInfo();
Comps.back().LocStart = Comps.back().LocEnd = ConsumeToken();
- enum class Kind { MemberAccess, ArraySubscript };
- auto DiagExt = [&](SourceLocation Loc, Kind K) {
- Diag(Loc, diag::ext_offsetof_member_designator)
- << (K == Kind::ArraySubscript) << (OOK == Sema::OOK_Macro);
- };
-
// FIXME: This loop leaks the index expressions on error.
while (true) {
if (Tok.is(tok::period)) {
@@ -2648,7 +2642,6 @@
SkipUntil(tok::r_paren, StopAtSemi);
return ExprError();
}
- DiagExt(Comps.back().LocStart, Kind::MemberAccess);
Comps.back().U.IdentInfo = Tok.getIdentifierInfo();
Comps.back().LocEnd = ConsumeToken();
} else if (Tok.is(tok::l_square)) {
@@ -2666,7 +2659,6 @@
SkipUntil(tok::r_paren, StopAtSemi);
return Res;
}
- DiagExt(Comps.back().LocStart, Kind::ArraySubscript);
Comps.back().U.E = Res.get();
ST.consumeClose();
Index: clang/include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticParseKinds.td
+++ clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -1607,11 +1607,6 @@
def err_export_empty : Error<"export declaration cannot be empty">;
}
-def ext_offsetof_member_designator : Extension<
- "using %select{a member access expression|an array subscript expression}0 "
- "within '%select{__builtin_offsetof|offsetof}1' is a Clang extension">,
- InGroup<GNUOffsetofExtensions>;
-
let CategoryName = "Generics Issue" in {
def err_objc_expected_type_parameter : Error<
Index: clang/docs/LanguageExtensions.rst
===================================================================
--- clang/docs/LanguageExtensions.rst
+++ clang/docs/LanguageExtensions.rst
@@ -2386,21 +2386,19 @@
const int offset_to_i = __builtin_offsetof(struct S, i);
const int ext1 = __builtin_offsetof(struct U { int i; }, i); // C extension
- const int ext2 = __builtin_offsetof(struct S, t.f[1]); // C & C++ extension
+ const int ext2 = __builtin_offsetof(struct S, t.f[1]);
**Description**:
This builtin is usable in an integer constant expression which returns a value
of type ``size_t``. The value returned is the offset in bytes to the subobject
designated by the member-designator from the beginning of an object of type
-``type-name``. Clang extends the required standard functionality in a few ways:
+``type-name``. Clang extends the required standard functionality in the
+following way:
* In C language modes, the first argument may be the definition of a new type.
Any type declared this way is scoped to the nearest scope containing the call
to the builtin.
-* The second argument may be a member-designator designated by a series of
- member access expressions using the dot (``.``) operator or array subscript
- expressions.
Query for this feature with ``__has_builtin(__builtin_offsetof)``.
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