)]}'
{
  "commit": "d72c8b02802c87386f5db3c7de6c79e921618fa3",
  "tree": "51f37accee4844869b4b6eba7e4ddaba5b387fd0",
  "parents": [
    "5430f73b501f9fc0a38c3768592f5f31bcbdf2f0"
  ],
  "author": {
    "name": "Michael Buch",
    "email": "michaelbuch12@gmail.com",
    "time": "Mon Jul 29 09:35:00 2024 +0100"
  },
  "committer": {
    "name": "GitHub",
    "email": "noreply@github.com",
    "time": "Mon Jul 29 09:35:00 2024 +0100"
  },
  "message": "[lldb][TypeSystemClang] Create VLAs of explicitly 0-size as ConstantArrayType (#100710)\n\nDepends on https://github.com/llvm/llvm-project/pull/100674\r\n\r\nCurrently, we treat VLAs declared as `int[]` and `int[0]` identically.\r\nI.e., we create them as `IncompleteArrayType`s. However, the\r\n`DW_AT_count` for `int[0]` *does* exist, and is retrievable without an\r\nexecution context. This patch decouples the notion of \"has 0 elements\"\r\nfrom \"has no known `DW_AT_count`\".\r\n\r\nThis aligns with how Clang represents `int[0]` in the AST (it treats it\r\nas a `ConstantArrayType` of 0 size).\r\n\r\nThis issue was surfaced when adapting LLDB to\r\nhttps://github.com/llvm/llvm-project/issues/93069. There, the\r\n`__compressed_pair_padding` type has a `char[0]` member. If we\r\npreviously got the `__compressed_pair_padding` out of a module (where\r\nclang represents `char[0]` as a `ConstantArrayType`), and try to merge\r\nthe AST with one we got from DWARF (where LLDB used to represent\r\n`char[0]` as an `IncompleteArrayType`), the AST structural equivalence\r\ncheck fails, resulting in silent ASTImporter failures. This manifested\r\nin a failure in `TestNonModuleTypeSeparation.py`.\r\n\r\n**Implementation**\r\n1. Adjust `ParseChildArrayInfo` to store the element counts of each VLA\r\ndimension as an `optional\u003cuint64_t\u003e`, instead of a regular `uint64_t`.\r\nSo when we pass this down to `CreateArrayType`, we have a better\r\nheuristic for what is an `IncompleteArrayType`.\r\n2. In `TypeSystemClang::GetBitSize`, if we encounter a\r\n`ConstantArrayType` simply return the size that it was created with. If\r\nwe couldn\u0027t determine the authoritative bound from DWARF during parsing,\r\nwe would\u0027ve created an `IncompleteArrayType`. This ensures that\r\n`GetBitSize` on arrays with `DW_AT_count 0x0` returns `0` (whereas\r\npreviously it would\u0027ve returned a `std::nullopt`, causing that\r\n`FieldDecl` to just get dropped during printing)",
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