aaron.ballman created this revision.
aaron.ballman added a reviewer: rsmith.
The C standard does not prohibit the _Atomic specifier on incomplete types,
which turns out to be sometimes useful.
This addresses PR37237.
Note that C++ still requires checking if the type is complete in order to
support member pointers under the Microsoft ABI (because that check completes
some information on the type), which is a use case we have in
test\SemaCXX\atomic-type.cpp.
https://reviews.llvm.org/D46112
Files:
include/clang/Basic/DiagnosticSemaKinds.td
lib/Sema/SemaType.cpp
test/Sema/atomic-type.c
Index: test/Sema/atomic-type.c
===================================================================
--- test/Sema/atomic-type.c
+++ test/Sema/atomic-type.c
@@ -16,7 +16,10 @@
extern _Atomic(int (*)(int(*)[10], int(*)[10])) mergetest;
_Atomic(int()) error1; // expected-error {{_Atomic cannot be applied to
function type}}
-_Atomic(struct ErrorS) error2; // expected-error {{_Atomic cannot be applied
to incomplete type}} expected-note {{forward declaration}}
+_Atomic(struct ErrorS) error2;
_Atomic(int[10]) error3; // expected-error {{_Atomic cannot be applied to
array type}}
_Atomic(const int) error4; // expected-error {{_Atomic cannot be applied to
qualified type}}
_Atomic(_Atomic(int)) error5; // expected-error {{_Atomic cannot be applied to
atomic type}}
+
+void g(_Atomic void *ptr);
+void h(_Atomic struct Incomplete *ptr); // expected-warning {{declaration of
'struct Incomplete' will not be visible outside of this function}}
Index: lib/Sema/SemaType.cpp
===================================================================
--- lib/Sema/SemaType.cpp
+++ lib/Sema/SemaType.cpp
@@ -8007,25 +8007,21 @@
QualType Sema::BuildAtomicType(QualType T, SourceLocation Loc) {
if (!T->isDependentType()) {
- // FIXME: It isn't entirely clear whether incomplete atomic types
- // are allowed or not; for simplicity, ban them for the moment.
- if (RequireCompleteType(Loc, T, diag::err_atomic_specifier_bad_type, 0))
- return QualType();
-
int DisallowedKind = -1;
if (T->isArrayType())
- DisallowedKind = 1;
+ DisallowedKind = 0;
else if (T->isFunctionType())
- DisallowedKind = 2;
+ DisallowedKind = 1;
else if (T->isReferenceType())
- DisallowedKind = 3;
+ DisallowedKind = 2;
else if (T->isAtomicType())
- DisallowedKind = 4;
+ DisallowedKind = 3;
else if (T.hasQualifiers())
- DisallowedKind = 5;
- else if (!T.isTriviallyCopyableType(Context))
+ DisallowedKind = 4;
+ else if (LangOpts.CPlusPlus && isCompleteType(Loc, T) &&
+ !T.isTriviallyCopyableType(Context))
// Some other non-trivially-copyable type (probably a C++ class)
- DisallowedKind = 6;
+ DisallowedKind = 5;
if (DisallowedKind != -1) {
Diag(Loc, diag::err_atomic_specifier_bad_type) << DisallowedKind << T;
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -5504,7 +5504,7 @@
"incomplete result type %0 in function definition">;
def err_atomic_specifier_bad_type : Error<
"_Atomic cannot be applied to "
- "%select{incomplete |array |function |reference |atomic |qualified |}0type "
+ "%select{array |function |reference |atomic |qualified |}0type "
"%1 %select{||||||which is not trivially copyable}0">;
// Expressions.
Index: test/Sema/atomic-type.c
===================================================================
--- test/Sema/atomic-type.c
+++ test/Sema/atomic-type.c
@@ -16,7 +16,10 @@
extern _Atomic(int (*)(int(*)[10], int(*)[10])) mergetest;
_Atomic(int()) error1; // expected-error {{_Atomic cannot be applied to function type}}
-_Atomic(struct ErrorS) error2; // expected-error {{_Atomic cannot be applied to incomplete type}} expected-note {{forward declaration}}
+_Atomic(struct ErrorS) error2;
_Atomic(int[10]) error3; // expected-error {{_Atomic cannot be applied to array type}}
_Atomic(const int) error4; // expected-error {{_Atomic cannot be applied to qualified type}}
_Atomic(_Atomic(int)) error5; // expected-error {{_Atomic cannot be applied to atomic type}}
+
+void g(_Atomic void *ptr);
+void h(_Atomic struct Incomplete *ptr); // expected-warning {{declaration of 'struct Incomplete' will not be visible outside of this function}}
Index: lib/Sema/SemaType.cpp
===================================================================
--- lib/Sema/SemaType.cpp
+++ lib/Sema/SemaType.cpp
@@ -8007,25 +8007,21 @@
QualType Sema::BuildAtomicType(QualType T, SourceLocation Loc) {
if (!T->isDependentType()) {
- // FIXME: It isn't entirely clear whether incomplete atomic types
- // are allowed or not; for simplicity, ban them for the moment.
- if (RequireCompleteType(Loc, T, diag::err_atomic_specifier_bad_type, 0))
- return QualType();
-
int DisallowedKind = -1;
if (T->isArrayType())
- DisallowedKind = 1;
+ DisallowedKind = 0;
else if (T->isFunctionType())
- DisallowedKind = 2;
+ DisallowedKind = 1;
else if (T->isReferenceType())
- DisallowedKind = 3;
+ DisallowedKind = 2;
else if (T->isAtomicType())
- DisallowedKind = 4;
+ DisallowedKind = 3;
else if (T.hasQualifiers())
- DisallowedKind = 5;
- else if (!T.isTriviallyCopyableType(Context))
+ DisallowedKind = 4;
+ else if (LangOpts.CPlusPlus && isCompleteType(Loc, T) &&
+ !T.isTriviallyCopyableType(Context))
// Some other non-trivially-copyable type (probably a C++ class)
- DisallowedKind = 6;
+ DisallowedKind = 5;
if (DisallowedKind != -1) {
Diag(Loc, diag::err_atomic_specifier_bad_type) << DisallowedKind << T;
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -5504,7 +5504,7 @@
"incomplete result type %0 in function definition">;
def err_atomic_specifier_bad_type : Error<
"_Atomic cannot be applied to "
- "%select{incomplete |array |function |reference |atomic |qualified |}0type "
+ "%select{array |function |reference |atomic |qualified |}0type "
"%1 %select{||||||which is not trivially copyable}0">;
// Expressions.
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