forked from OSchip/llvm-project
47e7ecdd7d
Right now we have one large AST for all types in LLDB. All ODR violations in types we reconstruct are resolved by just letting the ASTImporter handle the conflicts (either by merging types or somehow trying to introduce a duplicated declaration in the AST). This works ok for the normal types we build from debug information as most of them are just simple CXXRecordDecls or empty template declarations. However, with a loaded `std` C++ module we have alternative versions of pretty much all declarations in the `std` namespace that are much more fleshed out than the debug information declarations. They have all the information that is lost when converting to DWARF, such as default arguments, template default arguments, the actual uninstantiated template declarations and so on. When we merge these C++ module types into the big scratch AST (that might already contain debug information types) we give the ASTImporter the tricky task of somehow creating a consistent AST out of all these declarations. Usually this ends in a messy AST that contains a mostly broken mix of both module and debug info declarations. The ASTImporter in LLDB is also importing types with the MinimalImport setting, which usually means the only information we have when merging two types is often just the name of the declaration and the information that it contains some child declarations. This makes it pretty much impossible to even implement a better merging logic (as the names of C++ module declarations and debug info declarations are identical). This patch works around this whole merging problem by separating C++ module types from debug information types. This is done by splitting up the single scratch AST into two: One default AST for debug information and a dedicated AST for C++ module types. The C++ module AST is implemented as a 'specialised AST' that lives within the default ScratchTypeSystemClang. When we select the scratch AST we can explicitly request that we want such a isolated sub-AST of the scratch AST. I kept the infrastructure more general as we probably can use the same mechanism for other features that introduce conflicting types (such as programs that are compiled with a custom -wchar-size= option). There are just two places where we explicitly have request the C++ module AST: When we export persistent declarations (`$mytype`) and when we create our persistent result variable (`$0`, `$1`, ...). There are a few formatters that were previously assuming that there is only one scratch AST which I cleaned up in a preparation revision here (D92757). Reviewed By: aprantl Differential Revision: https://reviews.llvm.org/D92759 |
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| gtest_common.h | ||