Variadic generic function crash with inlining, tuple with 1 param or using inout parameter

[iDmitriyy]

Description

The crash appears only with certain combination of circumstances.

Reproduction

@inline(__always)
public func _countVariadicParams_for<each T>(_ params: repeat each T) -> Int {
  var count: Int = 0
  for _ in repeat each params {
    count += 1
  }
  return count
}

@inline(__always)
internal func _countVParams_ret_for<each L>(_ externalCount: inout Int) -> (repeat (each L).Type) {
  externalCount += _countVariadicParams_for(repeat (each L).self)
  
  let result = (repeat (each L).self)
  return result
}

var count: Int = 0
_countVParams_ret_for(&count) as (Int.Type)

Stack dump

xcrun swiftc -Osize swiftScript.swift -o swiftScript -v
Apple Swift version 6.0.3 (swiftlang-6.0.3.1.10 clang-1600.0.30.1)
Target: arm64-apple-macosx15.0
/Applications/Xcode-16.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-frontend -frontend -c -primary-file swiftScript.swift -target arm64-apple-macosx15.0 -Xllvm -aarch64-use-tbi -enable-objc-interop -stack-check -sdk /Applications/Xcode-16.2.0.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.2.sdk -color-diagnostics -Osize -new-driver-path /Applications/Xcode-16.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift-driver -empty-abi-descriptor -resource-dir /Applications/Xcode-16.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift -module-name swiftScript -disable-clang-spi -target-sdk-version 15.2 -target-sdk-name macosx15.2 -external-plugin-path '/Applications/Xcode-16.2.0.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/lib/swift/host/plugins#/Applications/Xcode-16.2.0.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/bin/swift-plugin-server' -external-plugin-path '/Applications/Xcode-16.2.0.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/local/lib/swift/host/plugins#/Applications/Xcode-16.2.0.app/Contents/Developer/Platforms/MacOSX.platform/Developer/usr/bin/swift-plugin-server' -plugin-path /Applications/Xcode-16.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/swift/host/plugins -plugin-path /Applications/Xcode-16.2.0.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/local/lib/swift/host/plugins -enable-default-cmo -o /var/folders/sn/c6hd64q14v7bkp5g_b1ltqb80000gn/T/TemporaryDirectory.0u3OMl/swiftScript-1.o
error: compile command failed due to signal 11 (use -v to see invocation)
Please submit a bug report (https://swift.org/contributing/#reporting-bugs) and include the crash backtrace.

Expected behavior

successful compilation

Environment

Swift 6, Xcode 16.2

Additional information

No crash when casting to as (Int.Type, Int.self) instead of as (Int.Type)
No crash when += is not done – externalCount += _countVariadicParams_for(repeat (each L).self) vs _countVariadicParams_for(repeat (each L).self)
No crash without @inline(__always)