hankadusikova created this revision.
hankadusikova added a reviewer: clang.
hankadusikova requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Removes this warning:
template<typename T, int N> struct StdArray {
T contents[N];
};
template<typename T, int N> struct AggregateAndEmpty : StdArray<T,N> { };
AggregateAndEmpty<int, 3> p = {1, 2, 3}; // <-- warning here about omitted
braces
This warning starts to be prominent when you have multiple levels of
inheritance for strong typing with aggregates:
template<typename T, int N> struct StdArray {
T contents[N];
};
template <typename T, int N> struct JustABaseClass : StdArray<T, N> {};
template <typename T, int N> struct OnionBaseClass : JustABaseClass<T, N> {};
OnionBaseClass<int,3> i = {1,2,3}; // instead {{{1,2,3}}}
This is my first patch for clang, so I hopefully didn't overlook something, but
all tests are green.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D100057
Files:
clang/lib/Sema/SemaInit.cpp
clang/test/SemaCXX/aggregate-initialization.cpp
Index: clang/test/SemaCXX/aggregate-initialization.cpp
===================================================================
--- clang/test/SemaCXX/aggregate-initialization.cpp
+++ clang/test/SemaCXX/aggregate-initialization.cpp
@@ -172,11 +172,20 @@
};
ArrayAndBaseClass<int, 3> z = {1, 2, 3}; // expected-warning {{suggest
braces}}
- // It's not clear whether we should be warning in this case. If this
- // pattern becomes idiomatic, it would be reasonable to suppress the
- // warning here too.
+ // This pattern is used for tagged aggregates and must not warn
template<typename T, int N> struct JustABaseClass : StdArray<T, N> {};
- JustABaseClass<int, 3> w = {1, 2, 3}; // expected-warning {{suggest braces}}
+ JustABaseClass<int, 3> w = {1, 2, 3};
+ // but this should be also ok
+ JustABaseClass<int, 3> v = {{1, 2, 3}};
+
+ template <typename T, int N> struct OnionBaseClass : JustABaseClass<T, N> {};
+ OnionBaseClass<int, 3> u = {1, 2, 3};
+ OnionBaseClass<int, 3> t = {{{1, 2, 3}}};
+
+ struct EmptyBase {};
+
+ template <typename T, int N> struct AggregateAndEmpty : StdArray<T, N>,
EmptyBase {};
+ AggregateAndEmpty<int, 3> p = {1, 2, 3}; // expected-warning {{suggest
braces}}
#endif
#pragma clang diagnostic pop
Index: clang/lib/Sema/SemaInit.cpp
===================================================================
--- clang/lib/Sema/SemaInit.cpp
+++ clang/lib/Sema/SemaInit.cpp
@@ -1007,21 +1007,37 @@
//
// (where std::array is an aggregate struct containing a single array field.
- // FIXME: Should aggregate initialization of a struct with a single
- // base class and no members also suppress the warning?
- if (Entity.getKind() != InitializedEntity::EK_Member || !Entity.getParent())
+ if (!Entity.getParent())
return false;
- auto *ParentRD =
- Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
- if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD))
- if (CXXRD->getNumBases())
- return false;
+ // Allows elide brace initialization for aggreagates with empty base
+ if (Entity.getKind() == InitializedEntity::EK_Base) {
+ auto *ParentRD =
+ Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
+ if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD)) {
+ if (CXXRD->getNumBases() == 1) {
+ return ParentRD->field_begin() == ParentRD->field_end();
+ }
+ }
+ return false;
+ }
- auto FieldIt = ParentRD->field_begin();
- assert(FieldIt != ParentRD->field_end() &&
- "no fields but have initializer for member?");
- return ++FieldIt == ParentRD->field_end();
+ // Allows elide brace initilization for aggregates with one member
+ if (Entity.getKind() == InitializedEntity::EK_Member) {
+ auto *ParentRD =
+ Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
+ if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD)) {
+ if (CXXRD->getNumBases()) {
+ return false;
+ }
+ }
+ auto FieldIt = ParentRD->field_begin();
+ assert(FieldIt != ParentRD->field_end() &&
+ "no fields but have initializer for member?");
+ return ++FieldIt == ParentRD->field_end();
+ }
+
+ return false;
}
/// Check whether the range of the initializer \p ParentIList from element
Index: clang/test/SemaCXX/aggregate-initialization.cpp
===================================================================
--- clang/test/SemaCXX/aggregate-initialization.cpp
+++ clang/test/SemaCXX/aggregate-initialization.cpp
@@ -172,11 +172,20 @@
};
ArrayAndBaseClass<int, 3> z = {1, 2, 3}; // expected-warning {{suggest braces}}
- // It's not clear whether we should be warning in this case. If this
- // pattern becomes idiomatic, it would be reasonable to suppress the
- // warning here too.
+ // This pattern is used for tagged aggregates and must not warn
template<typename T, int N> struct JustABaseClass : StdArray<T, N> {};
- JustABaseClass<int, 3> w = {1, 2, 3}; // expected-warning {{suggest braces}}
+ JustABaseClass<int, 3> w = {1, 2, 3};
+ // but this should be also ok
+ JustABaseClass<int, 3> v = {{1, 2, 3}};
+
+ template <typename T, int N> struct OnionBaseClass : JustABaseClass<T, N> {};
+ OnionBaseClass<int, 3> u = {1, 2, 3};
+ OnionBaseClass<int, 3> t = {{{1, 2, 3}}};
+
+ struct EmptyBase {};
+
+ template <typename T, int N> struct AggregateAndEmpty : StdArray<T, N>, EmptyBase {};
+ AggregateAndEmpty<int, 3> p = {1, 2, 3}; // expected-warning {{suggest braces}}
#endif
#pragma clang diagnostic pop
Index: clang/lib/Sema/SemaInit.cpp
===================================================================
--- clang/lib/Sema/SemaInit.cpp
+++ clang/lib/Sema/SemaInit.cpp
@@ -1007,21 +1007,37 @@
//
// (where std::array is an aggregate struct containing a single array field.
- // FIXME: Should aggregate initialization of a struct with a single
- // base class and no members also suppress the warning?
- if (Entity.getKind() != InitializedEntity::EK_Member || !Entity.getParent())
+ if (!Entity.getParent())
return false;
- auto *ParentRD =
- Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
- if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD))
- if (CXXRD->getNumBases())
- return false;
+ // Allows elide brace initialization for aggreagates with empty base
+ if (Entity.getKind() == InitializedEntity::EK_Base) {
+ auto *ParentRD =
+ Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
+ if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD)) {
+ if (CXXRD->getNumBases() == 1) {
+ return ParentRD->field_begin() == ParentRD->field_end();
+ }
+ }
+ return false;
+ }
- auto FieldIt = ParentRD->field_begin();
- assert(FieldIt != ParentRD->field_end() &&
- "no fields but have initializer for member?");
- return ++FieldIt == ParentRD->field_end();
+ // Allows elide brace initilization for aggregates with one member
+ if (Entity.getKind() == InitializedEntity::EK_Member) {
+ auto *ParentRD =
+ Entity.getParent()->getType()->castAs<RecordType>()->getDecl();
+ if (CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(ParentRD)) {
+ if (CXXRD->getNumBases()) {
+ return false;
+ }
+ }
+ auto FieldIt = ParentRD->field_begin();
+ assert(FieldIt != ParentRD->field_end() &&
+ "no fields but have initializer for member?");
+ return ++FieldIt == ParentRD->field_end();
+ }
+
+ return false;
}
/// Check whether the range of the initializer \p ParentIList from element
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