[all-commits] [llvm/llvm-project] 081723: [lldb][TypeSystem] Ensure that ParmVarDecls have t...

[Michael Buch via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 081723b9db84e78d7dd240b46af2aeb3b51b00be
      https://github.com/llvm/llvm-project/commit/081723b9db84e78d7dd240b46af2aeb3b51b00be
  Author: Michael Buch <michaelbuch12 at gmail.com>
  Date:   2025-01-27 (Mon, 27 Jan 2025)

  Changed paths:
    M lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
    M lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h
    M lldb/source/Plugins/SymbolFile/NativePDB/PdbAstBuilder.cpp
    M lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
    M lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp
    M lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h
    M lldb/unittests/Symbol/TestTypeSystemClang.cpp
    M lldb/unittests/SymbolFile/DWARF/DWARFASTParserClangTests.cpp

  Log Message:
  -----------
  [lldb][TypeSystem] Ensure that ParmVarDecls have the correct DeclContext (#124279)

While sifting through this part of the code I noticed that when we parse
C++ methods, `DWARFASTParserClang` creates two sets of `ParmVarDecls`,
one in `ParseChildParameters` and once in `AddMethodToCXXRecordType`.
The former is unused when we're dealing with methods. Moreover, the
`ParmVarDecls` we created in `ParseChildParameters` were created with an
incorrect `clang::DeclContext` (namely the DeclContext of the function,
and not the function itself). In Clang, there's
`ParmVarDecl::setOwningFunction` to adjust the DeclContext of a
parameter if the parameter was created before the FunctionDecl. But we
never used it.

This patch removes the `ParmVarDecl` creation from
`ParseChildParameters` and instead creates a
`TypeSystemClang::CreateParameterDeclarations` that ensures we set the
DeclContext correctly.

Note there is one differences in how `ParmVarDecl`s would be created
now: we won't set a ClangASTMetadata entry for any of the parameters. I
don't think this was ever actually useful for parameter DIEs anyway.

This wasn't causing any concrete issues (that I know of), but was quite
surprising. And this way of setting the parameters seems easier to
reason about (in my opinion).



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