Previously type sizes would be inconsistently sourced from either the LLVM type
or the FixedTypeInfo, depending on the call site. This was problematic because
TypeInfo operates with a resolution of whole bytes, which means that types such
as i1 would get a reported as having a size of 8. This patch now asserts that
all occurrences of the same type have the same size as the first, cached
occurence.
To avoid triggering the cached type verification assertion, this patch avoids
caching of storage-sized containers. It also removes the unique identifier from
forward declarations, which could lead to type confusion during LTO.
rdar://102367872
DebugInfoTypes didn't properly distinguish between types with an unknown size
and used 0 as the default value. This can cause types to show up in DWARF with a
size of 0, which will prevent LLDB from looking at the type further. In
practice, this meant that many resilient types (for example, SwiftUI Views)
couldn't be displayed in the debugger and just showed up as empty.
This patch does three things:
0. Make size in DebugTypeInfo optional.
1. Introduce CompletedDebugTypeInfo, a subclass of DebugTypeInfo where
size is guaranteed to be non-empty.
2. Change some APIs that only make sense with a size to use
CompletedDebugTypeInfo. This caused some churn because I needed to refactor
the get*Elements() functions back into their callers to facilitate the new
early-exit path. These functions are only called when compiling with
-gdwarf-types.
3. Change createOpaqueStructWithSizedContainer() to create a size-less forward
declaration instead of a zero-sized type for the inner type.
rdar://76973844
(cherry picked from commit b8e6eebdbc)
