Open Radar

 
Summary:
I was messing around with enums & protocols, attempting to recover functions for enum cases, when I hit a crasher.


Steps to Reproduce:
1. Compile this test case, _if you dare_:

public protocol P {
	typealias T
	static func c(T) -> Self
	static func C(T) -> Self
}
extension P {
	public static func C(x: T) -> Self {
		return .c(x)
	}
}

public enum E<T>: P {
	case C(T)

	public static func c(x: T) -> E {
		return C(x)
	}
}


Expected Results:
I expected this not to crash. I didn’t expect it to do much very useful tho.


Actual Results:
It crashed when compiling E.c().

expression kind should not survive to SILGen
UNREACHABLE executed at /Library/Caches/com.apple.xbs/Sources/swiftlang/swiftlang-700.0.38.1/src/swift/lib/SILGen/ASTVisitor.h:49!
0  swift                    0x000000010cd4ee0b llvm::sys::PrintStackTrace(__sFILE*) + 43
1  swift                    0x000000010cd4f54b SignalHandler(int) + 379
2  libsystem_platform.dylib 0x00007fff88493f1a _sigtramp + 26
3  swift                    0x000000010d348a1f FirstTarget + 60535
4  swift                    0x000000010cd4f346 abort + 22
5  swift                    0x000000010cd08e21 llvm::llvm_unreachable_internal(char const*, char const*, unsigned int) + 481
6  swift                    0x000000010af6feb3 swift::ASTVisitor<(anonymous namespace)::SILGenApply, void, void, void, void, void, void>::visit(swift::Expr*) + 5987
7  swift                    0x000000010af73d2f (anonymous namespace)::SILGenApply::visitApplyExpr(swift::ApplyExpr*) + 3279
8  swift                    0x000000010af64aef prepareApplyExpr(swift::Lowering::SILGenFunction&, swift::Expr*) + 175
9  swift                    0x000000010af649ff swift::Lowering::SILGenFunction::emitApplyExpr(swift::Expr*, swift::Lowering::SGFContext) + 47
10 swift                    0x000000010afa3c57 swift::ASTVisitor<(anonymous namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, void, swift::Lowering::SGFContext>::visit(swift::Expr*, swift::Lowering::SGFContext) + 87
…
Stack dump:
0.	Program arguments: /Applications/Xcode-7-beta.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/swift -frontend -c -primary-file either.swift -target x86_64-apple-darwin14.3.0 -enable-objc-interop -color-diagnostics -module-name either -o /var/folders/9y/f7n4rvx901nctm_5d16c1wm40000gn/T/either-3c4bb1.o 
1.	While emitting SIL for 'c' at either.swift:15:9


Regression:
It doesn’t crash if E.c() returns E.C(x) instead of just C(x).


Notes:
N/A