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From "Eric Milles (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (GROOVY-9064) STC: explicit declared variable type ignored in favor of assigned value type(s)
Date Thu, 04 Apr 2019 16:38:00 GMT

    [ https://issues.apache.org/jira/browse/GROOVY-9064?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16810046#comment-16810046
] 

Eric Milles commented on GROOVY-9064:
-------------------------------------

In order to maintain the declared type in the face of conditional assignments, like this:
{code:groovy}
@groovy.transform.CompileStatic
void meth() {
  Map map = getMapFromSomewhere()
  if (!map) {
    map = [a:1, b:'2']
  }
  // map infers to LinkedHashMap<String, Serializable<?>> without extra guard
condition
}
{code}

A guard condition also needs to be added to {{StaticTypeCheckingVisitor.popAssignmentTracking}}.

{code:java}
    protected Map<VariableExpression, ClassNode> popAssignmentTracking(final Map<VariableExpression,
List<ClassNode>> oldTracker) {
        Map<VariableExpression, ClassNode> assignments = new HashMap<VariableExpression,
ClassNode>();
        if (!typeCheckingContext.ifElseForWhileAssignmentTracker.isEmpty()) {
            for (Map.Entry<VariableExpression, List<ClassNode>> entry : typeCheckingContext.ifElseForWhileAssignmentTracker.entrySet())
{
                VariableExpression key = entry.getKey();
                List<ClassNode> allValues = entry.getValue();
                // GROOVY-6099: First element of the list may be null, if no assignment was
made before the branch
                List<ClassNode> nonNullValues = new ArrayList<ClassNode>(allValues.size());
                for (ClassNode value : allValues) {
                    if (value != null) nonNullValues.add(value);
                }
                ClassNode cn = lowestUpperBound(nonNullValues);
                // GRECLIPSE add -- GROOVY-9064
                if (key.isDynamicTyped())
                // GRECLIPSE end
                storeType(key, cn);
                assignments.put(key, cn);
            }
        }
        typeCheckingContext.ifElseForWhileAssignmentTracker = oldTracker;
        return assignments;
    }
{code}

> STC: explicit declared variable type ignored in favor of assigned value type(s)
> -------------------------------------------------------------------------------
>
>                 Key: GROOVY-9064
>                 URL: https://issues.apache.org/jira/browse/GROOVY-9064
>             Project: Groovy
>          Issue Type: Bug
>            Reporter: Eric Milles
>            Priority: Major
>
> Follow up to GROOVY-9058.  Consider the following:
> {code:groovy}
> List getSomeRows() { ... }
> @groovy.transform.CompileStatic
> void meth() {
>   List<Object[]> rows = getSomeRows()
>   rows.each { row ->
>     def col = row[0]
>   }
> }
> {code}
> The inferred type of {{rows}} is {{List}} and not {{List<Object[]>}} even though
the assignment cleared type checking.  This causes the inferred type of {{row}} to be {{Object}}
instead of {{Object[]}}.
> Similarly, {{List<String> list = []}} infers as {{ArrayList<String>}} instead
of the explicit declared type, and {{Map<String, ?> map = [:]}} infers to {{LinkedHasMap<...>}}
instead of the declared type.  In general, I think as long as the assignment is compatible,
the variable should retain its explicitly declared type regardless of assignments.



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