67c588c481
C doesn't allow empty structs but Clang/GCC support them and give them a size of 0.
LLDB implements this by checking the tag kind and if it's `DW_TAG_structure_type` then
we give it a size of 0 via an empty external RecordLayout. This is done because our
internal TypeSystem is always in C++ mode (which means we would give them a size
of 1).
The current check for when we have this special case is currently too lax as types with
`DW_TAG_structure_type` can also occur in C++ with types defined using the `struct`
keyword. This means that in a C++ program with `struct Empty{};`, LLDB would return
`0` for `sizeof(Empty)` even though the correct size is 1.
This patch removes this special case and replaces it with a generic approach that just
assigns empty structs the byte_size as specified in DWARF. The GCC/Clang special
case is handles as they both emit an explicit `DW_AT_byte_size` of 0. And if another
compiler decides to use a different byte size for this case then this should also be
handled by the same code as long as that information is provided via `DW_AT_byte_size`.
Reviewed By: werat, shafik
Differential Revision: https://reviews.llvm.org/D105471
21 lines
869 B
Python
21 lines
869 B
Python
import lldb
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from lldbsuite.test.decorators import *
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from lldbsuite.test.lldbtest import *
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from lldbsuite.test import lldbutil
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class TestCase(TestBase):
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mydir = TestBase.compute_mydir(__file__)
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def test(self):
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self.build()
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self.createTestTarget()
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# Empty structs/classes have size 1 in C++.
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self.expect_expr("sizeof(Empty) == sizeof_empty", result_value="true")
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self.expect_expr("sizeof(EmptyClass) == sizeof_empty_class", result_value="true")
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self.expect_expr("sizeof(SingleMember) == sizeof_single", result_value="true")
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self.expect_expr("sizeof(SingleMemberClass) == sizeof_single_class", result_value="true")
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self.expect_expr("sizeof(PaddingMember) == sizeof_padding", result_value="true")
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self.expect_expr("sizeof(PaddingMemberClass) == sizeof_padding_class", result_value="true")
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