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or virtual functions, but permit that error to be downgraded to a warning (with -Wno-error=incompatible-ms-struct), and officially support this kind of dual, ABI-mixing layout. The basic problem here is that projects which use ms_struct are often not very circumspect about what types they annotate; for example, some projects enable the pragma in a prefix header and then only selectively disable it around system header inclusions. They may only care about binary compatibility with MSVC for a subset of those structs, but that doesn't mean they have no binary compatibility concerns at all for the rest; thus we are essentially forced into supporting this hybrid ABI. But it's reasonable for us to at least point out the places where we're not making any guarantees. The original diagnostic was for dynamic classes, i.e. those with virtual functions or virtual bases; I've extended it to include all classes with bases, because we are not actually making any attempt to duplicate MSVC's base subobject layout in ms_struct (and it is indeed quite different from Itanium, even for non-virtual bases). rdar://16178895 llvm-svn: 202427
39 lines
1.3 KiB
C++
39 lines
1.3 KiB
C++
// RUN: %clang_cc1 -fsyntax-only -Wno-error=incompatible-ms-struct -verify -triple i686-apple-darwin9 -std=c++11 %s
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// RUN: %clang_cc1 -fsyntax-only -Wno-error=incompatible-ms-struct -verify -triple armv7-apple-darwin9 -std=c++11 %s
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// RUN: %clang_cc1 -fsyntax-only -DTEST_FOR_ERROR -verify -triple armv7-apple-darwin9 -std=c++11 %s
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#pragma ms_struct on
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struct A {
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unsigned long a:4;
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unsigned char b;
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};
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struct B : public A {
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#ifdef TEST_FOR_ERROR
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// expected-error@-2 {{ms_struct may not produce MSVC-compatible layouts for classes with base classes or virtual functions}}
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#else
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// expected-warning@-4 {{ms_struct may not produce MSVC-compatible layouts for classes with base classes or virtual functions}}
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#endif
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unsigned long c:16;
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int d;
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B();
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};
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static_assert(__builtin_offsetof(B, d) == 12,
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"We can't allocate the bitfield into the padding under ms_struct");
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// rdar://16178895
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struct C {
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#ifdef TEST_FOR_ERROR
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// expected-error@-2 {{ms_struct may not produce MSVC-compatible layouts for classes with base classes or virtual functions}}
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#else
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// expected-warning@-4 {{ms_struct may not produce MSVC-compatible layouts for classes with base classes or virtual functions}}
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#endif
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virtual void foo();
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long long n;
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};
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static_assert(__builtin_offsetof(C, n) == 8,
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"long long field in ms_struct should be 8-byte aligned");
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