Completely reimplement __builtin_offsetof, based on a patch by Roberto
Amadini.
This change introduces a new expression node type, OffsetOfExpr, that
describes __builtin_offsetof. Previously, __builtin_offsetof was
implemented using a unary operator whose subexpression involved
various synthesized array-subscript and member-reference expressions,
which was ugly and made it very hard to instantiate as a
template. OffsetOfExpr represents the AST more faithfully, with proper
type source information and a more compact representation.
OffsetOfExpr also has support for dependent __builtin_offsetof
expressions; it can be value-dependent, but will never be
type-dependent (like sizeof or alignof). This commit introduces
template instantiation for __builtin_offsetof as well.
There are two major caveats to this patch:
1) CodeGen cannot handle the case where __builtin_offsetof is not a
constant expression, so it produces an error. So, to avoid
regressing in C, we retain the old UnaryOperator-based
__builtin_offsetof implementation in C while using the shiny new
OffsetOfExpr implementation in C++. The old implementation can go
away once we have proper CodeGen support for this case, which we
expect won't cause much trouble in C++.
2) __builtin_offsetof doesn't work well with non-POD class types,
particularly when the designated field is found within a base
class. I will address this in a subsequent patch.
Fixes PR5880 and a bunch of assertions when building Boost.Python
tests.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@102542 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/SemaTemplate/instantiate-expr-5.cpp b/test/SemaTemplate/instantiate-expr-5.cpp
index 941dae4..916c4f9 100644
--- a/test/SemaTemplate/instantiate-expr-5.cpp
+++ b/test/SemaTemplate/instantiate-expr-5.cpp
@@ -1,4 +1,22 @@
-// RUN: %clang_cc1 -fsyntax-only %s
+// RUN: %clang_cc1 -fsyntax-only -verify %s
template <class A> int x(A x) { return x++; }
int y() { return x<int>(1); }
+
+namespace PR5880 {
+ template<typename T>
+ struct A {
+ static const int a = __builtin_offsetof(T, a.array[5].m); // expected-error{{error: no member named 'a' in 'HasM'}}
+ };
+ struct HasM {
+ float m;
+ };
+
+ struct ArrayOfHasM {
+ HasM array[10];
+ };
+
+ struct B { ArrayOfHasM a; };
+ A<B> x;
+ A<HasM> x2; // expected-note{{in instantiation of}}
+}