Fix a crash in constant expression binding

MOE_MIGRATED_REVID=170420622

2 files changed, 33 insertions, 0 deletions

diff --git a/java/com/google/turbine/binder/ConstEvaluator.java b/java/com/google/turbine/binder/ConstEvaluator.java
index 134a567..0598d8e 100644
--- a/java/com/google/turbine/binder/ConstEvaluator.java
+++ b/java/com/google/turbine/binder/ConstEvaluator.java
@@ -946,6 +946,9 @@ public strictfp class ConstEvaluator {
       throw error(tree.position(), ErrorKind.EXPRESSION_ERROR);
     }
     Const value = eval(tree);
+    if (value == null) {
+      throw error(tree.position(), ErrorKind.EXPRESSION_ERROR);
+    }
     switch (ty.tyKind()) {
       case PRIM_TY:
         return coerce((Const.Value) value, ((Type.PrimTy) ty).primkind());
diff --git a/javatests/com/google/turbine/binder/BinderErrorTest.java b/javatests/com/google/turbine/binder/BinderErrorTest.java
index 4c5abbd..aaac42d 100644
--- a/javatests/com/google/turbine/binder/BinderErrorTest.java
+++ b/javatests/com/google/turbine/binder/BinderErrorTest.java
@@ -294,6 +294,36 @@ public class BinderErrorTest {
           "   ^",
         },
       },
+      {
+        {
+          "public class Test {", //
+          "  @interface Anno {",
+          "    int[] value() default 0;",
+          "  }",
+          "  @Anno(value=Test.NO_SUCH) int x;",
+          "}",
+        },
+        {
+          "<>:5: error: could not evaluate constant expression", //
+          "  @Anno(value=Test.NO_SUCH) int x;",
+          "              ^",
+        },
+      },
+      {
+        {
+          "public class Test {", //
+          "  @interface Anno {",
+          "    String value() default \"\";",
+          "  }",
+          "  @Anno(value=null) int x;",
+          "}",
+        },
+        {
+          "<>:5: error: invalid annotation argument", //
+          "  @Anno(value=null) int x;",
+          "              ^",
+        },
+      },
     };
     return Arrays.asList((Object[][]) testCases);
   }