Compiler seg faults in exhaustive match code gen

[cquinn]

Latest master on MacOS 10.12.5.
Ponyc 0.14.0-a5ed8aa0 [release]
compiled with: llvm 3.9.1 -- Apple LLVM version 8.1.0 (clang-802.0.42)

The code demonstrating the problem is in the cli package in PR #1897 , source command_spec.pony lines 158-160 and 272-274

Building either of these 3-line workaround sections removed causes a segmentation fault during the Generating phase of ponyc.

The output I see is:

ponyc -V=4
Building builtin -> /Users/carl/ws/pony/cquinn/ponyc/packages/builtin
Building . -> /Users/carl/ws/pony/cquinn/ponyc/packages/cli
Building collections -> /Users/carl/ws/pony/cquinn/ponyc/packages/collections
Building ponytest -> /Users/carl/ws/pony/cquinn/ponyc/packages/ponytest
Building time -> /Users/carl/ws/pony/cquinn/ponyc/packages/time
Building buffered -> /Users/carl/ws/pony/cquinn/ponyc/packages/buffered
Generating
 Reachability
 Selector painting
 Data prototypes
 Data types
 Function prototypes
 Functions
Segmentation fault: 11

I will try to put together a smaller repro case, but in the meantime, I wanted to get an Issue in place to track it.

[cquinn]

Here is a smaller repro case:

type Union is (Bool | String)

class val X
  new val bool(default': (Bool | None) = None) =>
    let u =
      match default'
      | None => None
      | let d: Union => d
      //else
        // Ponyc issue: else can't happen, but segfaults without it
        //None
      end

actor Main
  new create(env: Env) =>
    X.bool()

[Perelandric]

This (at least the reduced example) appears to be fixed as of pull #2049

[jemc]

@cquinn can you confirm?

[cquinn]

Yes, this fixes the problem found in cli/command_spec.pony.