[lldb][Formatter] Get element type for unordered_maps from __hash_table::value_type #144517
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…le::value_type llvm#143501 changes usage of `__hash_value_type` in libcxx to an empty tag type. This type will no longer have a definition in DWARF. Currently the LLDB unordered_map formatter deduces the map's `element_type` by looking at the `__cc_` member of `__hash_value_type`. But that will no longer work because we only have its forward declaration. Since what we're really after is the type that `__hash_value_type` is wrapping, we can just look at the `__hash_table::value_type` typedef. With llvm#143501 that will now point to the `std::pair` element type (which used to be what we got from `__cc_`). TBD: need to double-check this works for older layouts. Quick glance at the code makes me suspicious of cases like `unordered_map<std::pair<int, int>, int>`
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✅ With the latest revision this PR passed the C/C++ code formatter. |
labath
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Jun 17, 2025
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I think that should work. One thing to look out for when it comes to typedefs is that they are not emitted if they aren't used (in the compilation unit). It should be fine as long as the type is referenced from a non-template member function, and I think that should be the case with the basic form of the insert method. (references from template member fn's are not enough as these are also only emitted when used)
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To be on the safe side I added an early-return for the new layout. Technically it would work for old layouts even without this early-return, but it kind of only worked by chance. This way regardless of what the |
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…le::value_type (llvm#144517) llvm#143501 changes usage of `__hash_value_type` in libcxx to an empty tag type. This type will no longer have a definition in DWARF. Currently the LLDB unordered_map formatter deduces the map's `element_type` by looking at the `__cc_` member of `__hash_value_type`. But that will no longer work because we only have its forward declaration. Since what we're really after is the type that `__hash_value_type` is wrapping, we can just look at the `__hash_table::value_type` typedef. With llvm#143501 that will now point to the `std::pair` element type (which used to be what we got from `__cc_`). TBD: need to double-check this works for older layouts. Quick glance at the code makes me suspicious of cases like `unordered_map<std::pair<int, int>, int>` (cherry picked from commit 382e3fd)
Michael137
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Ever since llvm#143501 and llvm#144517, these should pass. Adds tests for llvm#146040
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…tests on older Clang versions These only work after llvm/llvm-project#143501 and llvm/llvm-project#144517. Skip on older compilers. This currently fails on the macOS matrix bots that run the LLDB test-suite with older Clang versions. See llvm/llvm-project#146040.
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#143501 changes usage of
__hash_value_typein libcxx to an empty tag type. This type will no longer have a definition in DWARF. Currently the LLDB unordered_map formatter deduces the map'selement_typeby looking at the__cc_member of__hash_value_type. But that will no longer work because we only have its forward declaration. Since what we're really after is the type that__hash_value_typeis wrapping, we can just look at the__hash_table::value_typetypedef. With #143501 that will now point to thestd::pairelement type (which used to be what we got from__cc_).TBD: need to double-check this works for older layouts. Quick glance at the code makes me suspicious of cases like
unordered_map<std::pair<int, int>, int>