Github user melix commented on a diff in the pull request:
https://github.com/apache/groovy/pull/635#discussion_r150800145
--- Diff:
src/main/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java ---
@@ -3461,6 +3465,36 @@ public void visitTernaryExpression(final
TernaryExpression expression) {
popAssignmentTracking(oldTracker);
}
+ // currently just for empty literals, not for e.g.
Collections.emptyList() at present
+ /// it seems attractive to want to do this for more cases but perhaps
not all cases
+ private ClassNode checkForTargetType(final Expression expr, final
ClassNode type) {
+ if (typeCheckingContext.getEnclosingBinaryExpression() != null &&
isEmptyCollection(expr)) {
+ int op =
typeCheckingContext.getEnclosingBinaryExpression().getOperation().getType();
+ if (isAssignment(op)) {
+ VariableExpression target = (VariableExpression)
typeCheckingContext.getEnclosingBinaryExpression().getLeftExpression();
+ return adjustForTargetType(target.getType(), type);
+ }
+ }
+ return type;
+ }
+
+ private ClassNode adjustForTargetType(final ClassNode targetType,
final ClassNode resultType) {
+ if (targetType.isUsingGenerics() &&
missesGenericsTypes(resultType)) {
+ // unchecked assignment within ternary/elvis
+ // examples:
+ // List<A> list = existingAs ?: []
+ // in that case, the inferred type of the RHS is the type of
the RHS
+ // "completed" with generics type information available in the
LHS
+ return GenericsUtils.parameterizeType(targetType,
resultType.getPlainNodeReference());
+ }
+ return resultType;
+ }
+
+ private boolean isEmptyCollection(Expression expr) {
--- End diff --
Could be static.
---
