class TestCrash {
    init() throws { }
}

class HereComesTheCrash: TestCrash {
    override init() throws {
        fatalError()
    }    
}

class TestCrash {
    init() throws { }
}

class HereComesTheCrash: TestCrash {
    override init() throws {
        try super.init()
        fatalError()
    }    
}

> swift TestCrash.swift
SIL verification failed: Basic blocks must end with a terminator instruction: isa<TermInst>(BB.back())
In function:
// HereComesTheCrash.init()
sil hidden @_T09TestCrash012HereComesTheB0CACyKcfc : $@convention(method) (@owned HereComesTheCrash) -> (@owned HereComesTheCrash, @error Error) {
// %0                                             // user: %5
bb0(%0 : $HereComesTheCrash):
  %1 = alloc_box ${ var HereComesTheCrash }, let, name "self" // user: %2
  %2 = mark_uninitialized [derivedself] %1 : ${ var HereComesTheCrash } // users: %31, %24, %3
  %3 = project_box %2 : ${ var HereComesTheCrash }, 0 // users: %29, %28, %20, %5
  debug_value undef : $Error, var, name "$error", argno 1 // id: %4
  store %0 to [init] %3 : $*HereComesTheCrash     // id: %5
  // function_ref fatalError(_:file:line:)
  %6 = function_ref @_T0s10fatalErrors5NeverOSSyXK_s12StaticStringV4fileSu4linetF : $@convention(thin) (@owned @callee_owned () -> @owned String, StaticString, UInt) -> Never // user: %19
  // function_ref default argument 0 of fatalError(_:file:line:)
  %7 = function_ref @_T0s10fatalErrors5NeverOSSyXK_s12StaticStringV4fileSu4linetFfA_ : $@convention(thin) () -> @owned @callee_owned () -> @owned String // user: %8
  %8 = apply %7() : $@convention(thin) () -> @owned @callee_owned () -> @owned String // user: %19
  %9 = string_literal utf8 "TestCrash.swift"      // user: %14
  %10 = integer_literal $Builtin.Word, 15         // user: %14
  %11 = integer_literal $Builtin.Int1, -1         // user: %14
  %12 = metatype $@thin StaticString.Type         // user: %14
  // function_ref StaticString.init(_builtinStringLiteral:utf8CodeUnitCount:isASCII:)
  %13 = function_ref @_T0s12StaticStringVABBp08_builtinB7Literal_Bw17utf8CodeUnitCountBi1_7isASCIItcfC : $@convention(method) (Builtin.RawPointer, Builtin.Word, Builtin.Int1, @thin StaticString.Type) -> StaticString // user: %14
  %14 = apply %13(%9, %10, %11, %12) : $@convention(method) (Builtin.RawPointer, Builtin.Word, Builtin.Int1, @thin StaticString.Type) -> StaticString // user: %19
  // function_ref UInt.init(_builtinIntegerLiteral:)
  %15 = function_ref @_T0S2uBi2048_22_builtinIntegerLiteral_tcfC : $@convention(method) (Builtin.Int2048, @thin UInt.Type) -> UInt // user: %18
  %16 = metatype $@thin UInt.Type                 // user: %18
  %17 = integer_literal $Builtin.Int2048, 7       // user: %18
  %18 = apply %15(%17, %16) : $@convention(method) (Builtin.Int2048, @thin UInt.Type) -> UInt // user: %19
  %19 = apply %6(%8, %14, %18) : $@convention(thin) (@owned @callee_owned () -> @owned String, StaticString, UInt) -> Never
  %20 = load [take] %3 : $*HereComesTheCrash      // user: %21
  %21 = upcast %20 : $HereComesTheCrash to $TestCrash // user: %23
  // function_ref TestCrash.init()
  %22 = function_ref @_T09TestCrashAACAByKcfc : $@convention(method) (@owned TestCrash) -> (@owned TestCrash, @error Error) // user: %23
  try_apply %22(%21) : $@convention(method) (@owned TestCrash) -> (@owned TestCrash, @error Error), normal bb1, error bb2 // id: %23
  destroy_value %2 : ${ var HereComesTheCrash }   // id: %24
  return %29 : $HereComesTheCrash                 // id: %25

// %26                                            // user: %27
bb1(%26 : $TestCrash):                            // Preds: bb0
  %27 = unchecked_ref_cast %26 : $TestCrash to $HereComesTheCrash // user: %28
  store %27 to [init] %3 : $*HereComesTheCrash    // id: %28
  %29 = load [copy] %3 : $*HereComesTheCrash      // user: %25

// %30                                            // user: %32
bb2(%30 : $Error):                                // Preds: bb0
  destroy_value %2 : ${ var HereComesTheCrash }   // id: %31
  throw %30 : $Error                              // id: %32
} // end sil function '_T09TestCrash012HereComesTheB0CACyKcfc'

0  swift           0x0000000003ae91b8
1  swift           0x0000000003ae98f6
2  libpthread.so.0 0x00007f97016af390
3  libc.so.6       0x00007f96ffdee428 gsignal + 56
4  libc.so.6       0x00007f96ffdf002a abort + 362
5  swift           0x00000000010d59f7
6  swift           0x00000000010d30bc
7  swift           0x00000000010cfe5b
8  swift           0x0000000000bbcc67
9  swift           0x0000000000bc4aba
10 swift           0x0000000000bbde47
11 swift           0x0000000000c544ed
12 swift           0x0000000000c54258
13 swift           0x0000000000bc191b
14 swift           0x0000000000bc28c4
15 swift           0x0000000000bc2eff
16 swift           0x00000000004ad7d6
17 swift           0x00000000004aa52b
18 swift           0x0000000000465564
19 libc.so.6       0x00007f96ffdd9830 __libc_start_main + 240
20 swift           0x0000000000462e29
Stack dump:
0.    Program arguments: /swiftlang/usr/bin/swift -frontend -c -primary-file TestCrash.swift -target x86_64-unknown-linux-gnu -disable-objc-interop -color-diagnostics -module-name TestCrash -o /tmp/TestCrash-bc091a.o
1.    While silgen constructor initializer SIL function "@_T09TestCrash012HereComesTheB0CACyKcfc".
 for 'init()' at TestCrash.swift:6:14
<unknown>:0: error: unable to execute command: Aborted
<unknown>:0: error: compile command failed due to signal 6 (use -v to see invocation)