[lldb][DWARFASTParserClang] Eagerly search definitions for Objective-C classes #9749
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…C classes This patch essentially reverts the definition DIE delay changes (in llvm#98361) for Objective-C. The problem we've been seeing is as follows: 1. An Objetive-C class extension is represented in DWARF as: ``` DW_TAG_structure_type DW_AT_declaration (true) DW_AT_name ("ExtendedClass") DW_TAG_subprogram DW_AT_name ("extensionMethod") ... ``` I.e., it is a forward declaration of the extended class, but that forward declaration has children methods. 2. When we set a breakpoint in one of those methods we parse the subprogram DIE and try to create an `ObjCMethodDecl` for it (and attach it to the context). 3. When parsing the subprogram DIE, we first try to complete the DeclContext. Because `ExtendedClass` is only a forward declaration and we don't try to fetch the definition DIE eagerly anymore, LLDB has no idea that we're dealing with an Objective-C type. So it goes ahead and constructs it as a `CXXRecordDecl`. This confuses `DWARFASTParserClang::ParseObjCMethod` because it expects the context to be an `clang::ObjCObjectOrInterfaceType`. So it bails and we end up crashing because we try to attach a `FunctionDecl` to an incomplete `CXXRecordDecl` (which wasn't even forcefully completed). Since there's no good way to tell whether a forward declaration is an Objective-C type, the only solution I can really see here is to eagerly fetch the definition for Objective-C types.
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This patch essentially reverts the definition DIE delay changes (in llvm#98361) for Objective-C.
The problem we've been seeing is as follows:
I.e., it is a forward declaration of the extended class, but that forward declaration has children methods.
When we set a breakpoint in one of those methods we parse the subprogram DIE and try to create an
ObjCMethodDeclfor it (and attach it to the context).When parsing the subprogram DIE, we first try to complete the DeclContext. Because
ExtendedClassis only a forward declaration and we don't try to fetch the definition DIE eagerly anymore, LLDB has no idea that we're dealing with an Objective-C type. So it goes ahead and constructs it as aCXXRecordDecl. This confusesDWARFASTParserClang::ParseObjCMethodbecause it expects the context to be anclang::ObjCObjectOrInterfaceType. So it bails and we end up crashing because we try to attach aFunctionDeclto an incompleteCXXRecordDecl(which wasn't even forcefully completed).Since there's no good way to tell whether a forward declaration is an Objective-C type, the only solution I can really see here is to eagerly fetch the definition for Objective-C types.