[stdlib] Introduce demangle function #25314
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CC: @mikeash |
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There's a possible bug in the swift_demangle implementation, assuming that the mangledName doesn't need to be null-terminated.
- if (!Demangle::isSwiftSymbol(mangledName))
+ if (!Demangle::isSwiftSymbol(StringRef(mangledName, mangledNameLength)))The comments in Demangle.h and Demangle.cpp could be updated. For example:
-// NB: This function is not used directly in the Swift codebase, but is
+// NB: This function is used in the Swift standard library, but is also
// exported for Xcode support and is used by the sanitizers. Please coordinate
// before changing.
stdlib/public/core/Demangle.swift
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If mangledNameBuffer is always null-terminated then you could change it to mangledName: UnsafePointer<CChar>, so that String arguments can be implicitly converted.
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We already have the String argument version, so I'm unsure why supporting a pointer version for implicit conversion is necessary.
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I'm suggesting that:
-
either
mangledNameBuffer: UnsafeBufferPointer<Int8>doesn't need to be null-terminated; -
or
mangledName: UnsafePointer<Int8>would make the thirddemanglefunction unnecessary.
On the other hand, John McCall wants to deprecate the implicit conversions.
By the way, are Int8 or UInt8 elements more suitable for UTF-8 string parameters?
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If we use your suggestion about using StringRef(mangledName, mangledNameLength)) mangledNameBuffer doesn't need to be null terminated. However, we must commit to either the name buffer being null terminated (because we calculate length with nameBuffer.count - 1), or must not be null terminated (nameBuffer.count).
As for Int8 or UInt8, CChar maps to Int8 and the string functions withCString and utf8CString.withUnsafeBufferPointer, etc all have Int8 element types. withUTF8 on the other hand uses UInt8, so I'm unsure. I think going with Int8 is the better call because of the CChar typealias.
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CChar is either signed or unsigned, depending on the platform; it reflects the signedness of the C char type.
newline remove ? remove user label prefixes Add swift_demangle shim in SwiftShims INTERNAL Update based on forum comments Update tests Address some feedback
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I'm going to close this PR and open a new one once we've discussed more about this on the forums. |
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This is just an initial implementation for the demangle function that we're discussing over here. Documentation might need some love.
Tests should fail right now because it's dependent on #25308 being resolved first.
cc: @jckarter