Check Return Types in Validator

[mgaudet]

Adding a small test case to the ILValidator test shows what's going on here quite clearly:

diff --git a/fvtest/compilertriltest/ILValidatorTest.cpp b/fvtest/compilertriltest/ILValidatorTest.cpp
index 0fe1e286..3348177c 100644
--- a/fvtest/compilertriltest/ILValidatorTest.cpp
+++ b/fvtest/compilertriltest/ILValidatorTest.cpp
@@ -65,6 +65,11 @@ INSTANTIATE_TEST_CASE_P(ILValidatorChildrenCountDeathTest, IllformedTrees, ::tes
     "(method return=Int64 (block (lreturn (ladd (lconst 1) (lconst 1) (lconst 1)))))"
     ));

+INSTANTIATE_TEST_CASE_P(ILValidatorReturnMismatchDeathTest, IllformedTrees, ::testing::Values(
+    "(method return=Int32 (block (lreturn (lconst 1) )))"                   // incorrect return type of sig
+    ));
+
+

Essentially, the declared return type of a function isn't checked against the return opcode generated for that function -- so, the above currently validates.

[charliegracie]

We may need to revisit the DeathTests due to #1881 and the significant amount of time they take to run on OS X.