Make CompilerType::getBitSize() / getByteSize() return an optional result. NFC
The code in LLDB assumes that CompilerType and friends use the size 0
as a sentinel value to signal an error. This works for C++, where no
zero-sized type exists, but in many other programming languages
(including I believe C) types of size zero are possible and even
common. This is a particular pain point in swift-lldb, where extra
code exists to double-check that a type is *really* of size zero and
not an error at various locations.
To remedy this situation, this patch starts by converting
CompilerType::getBitSize() and getByteSize() to return an optional
result. To avoid wasting space, I hand-rolled my own optional data
type assuming that no type is larger than what fits into 63
bits. Follow-up patches would make similar changes to the ValueObject
hierarchy.
rdar://problem/47178964
Differential Revision: https://reviews.llvm.org/D56688
llvm-svn: 351214
diff --git a/lldb/source/Core/ValueObjectConstResult.cpp b/lldb/source/Core/ValueObjectConstResult.cpp
index e857702..f6e32c0 100644
--- a/lldb/source/Core/ValueObjectConstResult.cpp
+++ b/lldb/source/Core/ValueObjectConstResult.cpp
@@ -198,10 +198,11 @@
uint64_t ValueObjectConstResult::GetByteSize() {
ExecutionContext exe_ctx(GetExecutionContextRef());
-
- if (m_byte_size == 0)
- SetByteSize(
- GetCompilerType().GetByteSize(exe_ctx.GetBestExecutionContextScope()));
+ if (m_byte_size == 0) {
+ if (auto size =
+ GetCompilerType().GetByteSize(exe_ctx.GetBestExecutionContextScope()))
+ SetByteSize(*size);
+ }
return m_byte_size;
}