From 8d3d38f27fabeddaedb9fed7893f807fc5f09503 Mon Sep 17 00:00:00 2001
From: Joe Eli McIlvain <joe.eli.mac@gmail.com>
Date: Fri, 2 Jun 2017 23:58:54 -0700
Subject: [PATCH] Fix compiler crash on non-existent field reference in
 constructor.

Resolves #1932.
---
 src/libponyc/pass/refer.c |  4 +++-
 test/libponyc/badpony.cc  | 13 +++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/libponyc/pass/refer.c b/src/libponyc/pass/refer.c
index 0482e84b34..bddfcd550c 100644
--- a/src/libponyc/pass/refer.c
+++ b/src/libponyc/pass/refer.c
@@ -633,7 +633,9 @@ static bool is_lvalue(pass_opt_t* opt, ast_t* ast, bool need_value)
       if(ast_id(left) == TK_THIS)
       {
         ast_t* def = (ast_t*)ast_data(ast);
-        pony_assert(def != NULL);
+
+        if(def == NULL)
+          return false;
 
         switch(ast_id(def))
         {
diff --git a/test/libponyc/badpony.cc b/test/libponyc/badpony.cc
index 26385cb12b..1e364738a6 100644
--- a/test/libponyc/badpony.cc
+++ b/test/libponyc/badpony.cc
@@ -571,6 +571,19 @@ TEST_F(BadPonyTest, CallArgTypeErrorInsideTuple)
   TEST_ERRORS_1(src, "argument not a subtype of parameter");
 }
 
+TEST_F(BadPonyTest, NonExistFieldReferenceInConstructor)
+{
+  // From issue #1932
+  const char* src =
+    "actor Main\n"
+    "  new create(env: Env) =>\n"
+    "    this.x = None";
+
+  TEST_ERRORS_2(src,
+    "can't find declaration of 'x'",
+    "left side must be something that can be assigned to");
+}
+
 TEST_F(BadPonyTest, TypeArgErrorInsideReturn)
 {
   const char* src =