From 56f0dbd02f6ba1f8279decd94551a9ade767179c Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Thu, 10 Sep 2020 12:53:55 -0700
Subject: [PATCH] Prevent case compilation from crashing and burning.

---
 code/compiler/13/ast.cpp | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/code/compiler/13/ast.cpp b/code/compiler/13/ast.cpp
index 693cafd..a59e995 100644
--- a/code/compiler/13/ast.cpp
+++ b/code/compiler/13/ast.cpp
@@ -204,10 +204,6 @@ type_ptr ast_case::typecheck(type_mgr& mgr, type_env_ptr& env) {
 
     input_type = mgr.resolve(case_type, var);
     type_app* app_type;
-    // if(!(app_type = dynamic_cast<type_app*>(input_type.get())) ||
-    //         !dynamic_cast<type_data*>(app_type->constructor.get())) {
-    //     throw type_error("attempting case analysis of non-data type", of->loc);
-    // }
 
     return branch_type;
 }
@@ -407,17 +403,17 @@ void ast_case::compile(const env_ptr& env, std::vector<instruction_ptr>& into) c
     of->compile(env, into);
     into.push_back(instruction_ptr(new instruction_eval()));
 
-    if((data = dynamic_cast<type_data*>(app_type->constructor.get()))) {
+    if(app_type && (data = dynamic_cast<type_data*>(app_type->constructor.get()))) {
         compile_case<case_strategy_data>(*this, env, data, into);
         return;
-    } else if((internal = dynamic_cast<type_internal*>(app_type->constructor.get()))) {
+    } else if(app_type && (internal = dynamic_cast<type_internal*>(app_type->constructor.get()))) {
         if(internal->name == "Bool") {
             compile_case<case_strategy_bool>(*this, env, data, into);
             return;
         }
     }
 
-    throw std::runtime_error("no known way to compile case expression");
+    throw type_error("attempting unsupported case analysis", of->loc);
 }
 
 void ast_let::print(int indent, std::ostream& to) const {