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Sema: Disallow inheriting from classes with flexible array members 

Flexible array members inherently index off of the end of their parent
type.

We shouldn't allow this type to be used as a base, virtual or otherwise,
because indexing off the end may find us inside of another base or the
derived types members.

llvm-svn: 193923
This commit is contained in:
David Majnemer 2013-11-02 12:00:36 +00:00
parent 4589760efd
commit 9b1754d058
2 changed files with 14 additions and 0 deletions
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2
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -5885,6 +5885,8 @@ def err_base_must_be_class : Error<"base specifier must name a class">;
def err_union_as_base_class : Error<"unions cannot be base classes">;
def err_circular_inheritance : Error<
"circular inheritance between %0 and %1">;
def err_base_class_has_flexible_array_member : Error<
"base class %0 has a flexible array member">;
def err_incomplete_base_class : Error<"base class has incomplete type">;
def err_duplicate_base_class : Error<
"base class %0 specified more than once as a direct base class">;

12
clang/lib/Sema/SemaDeclCXX.cpp
View File

@ -1370,6 +1370,18 @@ Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
CXXRecordDecl *CXXBaseDecl = cast<CXXRecordDecl>(BaseDecl);
assert(CXXBaseDecl && "Base type is not a C++ type");
// A class which contains a flexible array member is not suitable for use as a
// base class:
// - If the layout determines that a base comes before another base,
// the flexible array member would index into the subsequent base.
// - If the layout determines that base comes before the derived class,
// the flexible array member would index into the derived class.
if (CXXBaseDecl->hasFlexibleArrayMember()) {
Diag(BaseLoc, diag::err_base_class_has_flexible_array_member)
<< CXXBaseDecl->getDeclName();
return 0;
}
// C++ [class]p3:
// If a class is marked final and it appears as a base-type-specifier in
// base-clause, the program is ill-formed.