[lldb][Type Completion] Fix completion of ObjCObjectTypes #8890
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adrian-prantl
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Jun 13, 2024
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The problem was introduced in: ``` commit e68f76a9e59104e2bfb972155af8ff04310cd078 Author: Michael Buch <[email protected]> Date: Fri Feb 16 14:35:34 2024 +0000 [lldb][TypeSystemClang][NFCI] Factor completion logic out of GetCompleteQualType ``` This introduced an incorrect `llvm::dyn_cast_or_null` check causing us to incorrectly claim that we failed to complete a type. This manifested in a crash when running following expression: ``` expr -l objc -- *(id)0x1234 ``` rdar://129633122
This is a minimal reproducer for a crash reported internally where we would try to call `DumpTypeDescription` on an incomplete type. This crash surfaced as part of an NFC refactor of some of the logic in `GetCompleteQualType`: ``` (lldb) expr -l objc -- *(id)0x1234 Stack dump: 0. Program arguments: ./bin/lldb a.out -o "b main" -o run -o "expr -l objc -- *(id)0x1234" Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var LLVM_SYMBOLIZER_PATH to point to it): 0 lldb 0x0000000102ec768c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56 1 lldb 0x0000000102ec6010 llvm::sys::RunSignalHandlers() + 112 2 lldb 0x0000000102ec7fa8 SignalHandler(int) + 292 3 libsystem_platform.dylib 0x000000018c7a8c44 _sigtramp + 56 4 LLDB 0x0000000116b2030c lldb_private::TypeSystemClang::DumpTypeDescription(void*, lldb_private::Stream&, lldb::DescriptionLevel, lldb_private::ExecutionContextScope*) + 588 5 LLDB 0x00000001166b5124 lldb_private::CompilerType::DumpTypeDescription(lldb_private::Stream*, lldb::DescriptionLevel, lldb_private::ExecutionContextScope*) const + 228 6 LLDB 0x0000000116d4f08c IRForTarget::CreateResultVariable(llvm::Function&) + 2076 ``` rdar://129633122
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The problem was introduced in:
This introduced an incorrect
llvm::dyn_cast_or_nullcheck causing us to incorrectly claim that we failed to complete a type.This manifested in a crash when running following expression:
rdar://129633122