Simplify the thunk names we generate for test functions. #750
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Parameterized test functions with the same name but different argument types currently get the same generated names from swift-syntax, so we do some additional decorating to ensure uniqueness. This results in very long symbol names that `swift-demangle` has trouble with. This PR changes the decorating formula. Previously, we would include a copy of the test function's signature (stripped of whitespace, Unicode, and non-identifier-friendly ASCII) and, if the identifier contained non-ASCII characters, the CRC32 of the identifier for further uniqueness. This change drops the copy of the identifier name and always includes the CRC32. Collisions are only possible for fully-qualified test function names that are _identical_, and I naïvely judge the risk of those collisions to be sufficiently low that we can make this change. For `ZipTests.allElementsEqual😀(i:j:)`` we currently generate a thunk named: ``` $s12TestingTests03ZipB0V0022allElementsEqual_oxFJo4TestfMp_43funcallElementsEqual__i_Int_j_Int__5bcb7b35fMu_ ``` This change would change it to: ``` $s12TestingTests03ZipB0V0022allElementsEqual_oxFJo4TestfMp_9Z5bcb7b35fMu_ ``` The benefit of the change is that the generated names are shorter and easier to read when expanding a macro. There may also be some benefit on Windows where the linker has a 65KB symbol name cap, although we're not exporting these symbols so probably not.
grynspan
added
enhancement
grynspan
requested review from
stmontgomery,
dennisweissmann,
briancroom,
SeanROlszewski and
suzannaratcliff
as code owners
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@swift-ci test |
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@swift-ci test |
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@swift-ci test Windows |
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@stmontgomery previously gave me a thumbs-up on the concept of the change, though not the diff itself. |
Is there some bug there that needs to be reported? |
stmontgomery
approved these changes
Oct 7, 2024
I don't think so. It's not a bug with |
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Parameterized test functions with the same name but different argument types currently get the same generated names from swift-syntax, so we do some additional decorating to ensure uniqueness. This results in very long symbol names that
swift-demanglehas trouble with.This PR changes the decorating formula. Previously, we would include a copy of the test function's signature (stripped of whitespace, Unicode, and non-identifier-friendly ASCII) and, if the identifier contained non-ASCII characters, the CRC32 of the identifier for further uniqueness. This change drops the copy of the identifier name and always includes the CRC32. Collisions are only possible for fully-qualified test function names that are identical, and I naïvely judge the risk of those collisions to be sufficiently low that we can make this change.
For
ZipTests.allElementsEqual😀(i:j:)we currently generate a thunk named:This change would change it to:
Which demangles to:
The benefit of the change is that the generated names are shorter and easier to read when expanding a macro, and play better with the demangler. There may also be some benefit on Windows where the linker has a 65KB symbol name cap, although we're not exporting these symbols so probably not.
Checklist: