Handle uninferred type parameter in array accesses (Fixes #3020) (#3107)

typetools · Feb 27, 2020 · 24bcf17 · 24bcf17
1 parent c3d7f6c
commit 24bcf17
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Showing 2 changed files with 29 additions and 2 deletions.
diff --git a/checker/tests/nullness/Issue3020.java b/checker/tests/nullness/Issue3020.java
@@ -0,0 +1,17 @@
+enum Issue3020 {
+    INSTANCE;
+
+    void retrieveConstant() {
+        Class<?> theClass = Issue3020.class;
+        // :: error: (accessing.nullable)
+        Object unused = passThrough(theClass.getEnumConstants())[0];
+    }
+
+    void nonNullArray(String[] p) {
+        Object unused = passThrough(p)[0];
+    }
+
+    <T> T passThrough(T t) {
+        return t;
+    }
+}
diff --git a/framework/src/main/java/org/checkerframework/framework/type/TypeFromExpressionVisitor.java b/framework/src/main/java/org/checkerframework/framework/type/TypeFromExpressionVisitor.java
@@ -36,6 +36,7 @@
 import org.checkerframework.framework.type.AnnotatedTypeMirror.AnnotatedWildcardType;
 import org.checkerframework.framework.type.visitor.AnnotatedTypeMerger;
 import org.checkerframework.framework.util.AnnotatedTypes;
+import org.checkerframework.javacutil.BugInCF;
 import org.checkerframework.javacutil.Pair;
 import org.checkerframework.javacutil.TreeUtils;
 
@@ -224,8 +225,17 @@ public AnnotatedTypeMirror visitArrayAccess(ArrayAccessTree node, AnnotatedTypeF
             f.visitorState.setAssignmentContext(null);
 
             AnnotatedTypeMirror type = f.getAnnotatedType(node.getExpression());
-            assert type instanceof AnnotatedArrayType;
-            return ((AnnotatedArrayType) type).getComponentType();
+            if (type.getKind() == TypeKind.ARRAY) {
+                return ((AnnotatedArrayType) type).getComponentType();
+            } else if (type.getKind() == TypeKind.WILDCARD
+                    && ((AnnotatedWildcardType) type).isUninferredTypeArgument()) {
+                // Clean-up after Issue #979.
+                AnnotatedTypeMirror wcbound = ((AnnotatedWildcardType) type).getExtendsBound();
+                if (wcbound instanceof AnnotatedArrayType) {
+                    return ((AnnotatedArrayType) wcbound).getComponentType();
+                }
+            }
+            throw new BugInCF("Unexpected type: " + type);
         } finally {
             f.visitorState.setAssignmentContext(preAssCtxt);
         }