[swift] Inner functions cannot have recursive calls

Originator:chriseidhof
Number:rdar://17746344 Date Originated:21-Jul-2014
Status:Open Resolved:
Product: Product Version:
Classification: Reproducible:
 
Summary:
When creating an inner function (a function inside a function) the inner function cannot recurse.

Steps to Reproduce:
The simplest (although non-sensical) function I could come up with:

func hello() {
    func next() {
        return next()
    }    
}

The compiler fails to generate code for this. Also, consider the slightly more advanced function:

func hello2() {
    var i = 0
    func next(x: Int) -> Int {
        i+=1
        return next(i)
    }
    
}

Expected Results:
I expected this to compile (and run infinitely)

Actual Results:
In the case above, the compiler fails with:

Instruction does not dominate all uses!
  %6 = bitcast %SS* %0 to %swift.opaque*, !dbg !74
  %2 = bitcast %swift.opaque* %6 to i8*, !dbg !71
LLVM ERROR: Broken function found, compilation aborted!

For hello2, the compiler fails with a different error message:

0  swift                    0x0000000101100de8 llvm::sys::PrintStackTrace(__sFILE*) + 40
1  swift                    0x00000001011012d4 SignalHandler(int) + 452
2  libsystem_platform.dylib 0x00007fff885995aa _sigtramp + 26
3  libsystem_platform.dylib 0x00007ff030b86010 _sigtramp + 2824784512
4  swift                    0x00000001004c0e83 swift::irgen::CallEmission::emitCallSite(bool) + 115
5  swift                    0x00000001004c0c81 swift::irgen::CallEmission::emitToUnmappedExplosion(swift::irgen::Explosion&) + 33
6  swift                    0x00000001004c1619 swift::irgen::CallEmission::emitToExplosion(swift::irgen::Explosion&) + 505
7  swift                    0x0000000100542835 swift::SILVisitor<(anonymous namespace)::IRGenSILFunction, void>::visit(swift::ValueBase*) + 51237
8  swift                    0x0000000100535800 swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 8896
9  swift                    0x00000001004b6f57 swift::irgen::IRGenModule::emitLazyDefinitions() + 199
10 swift                    0x000000010052261d performIRGeneration(swift::IRGenOptions&, swift::Module*, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, swift::SourceFile*, unsigned int) + 1997
11 swift                    0x0000000100522f23 swift::performIRGeneration(swift::IRGenOptions&, swift::SourceFile&, swift::SILModule*, llvm::StringRef, llvm::LLVMContext&, unsigned int) + 51
12 swift                    0x0000000100494b8e frontend_main(llvm::ArrayRef<char const*>, char const*, void*) + 4958
13 swift                    0x000000010049381d main + 1533
14 libdyld.dylib            0x00007fff90e4e5fd start + 1

Version:
Xcode6-Beta3

Notes:


Configuration:


Attachments:

Comments

This is a known bug.

(People often encourage to file duplicates as a way of casting votes, but in case of Swift in particular, Swift Lattner explicitly asked not to. So don't.)

By radexpl at July 21, 2014, 7:44 p.m. (reply...)

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