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https://issues.apache.org/jira/browse/GROOVY-8255?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16251237#comment-16251237
]
ASF GitHub Bot commented on GROOVY-8255:
----------------------------------------
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.
> Odd problems with flow typing and generics in Groovy 2.4.12+
> ------------------------------------------------------------
>
> Key: GROOVY-8255
> URL: https://issues.apache.org/jira/browse/GROOVY-8255
> Project: Groovy
> Issue Type: Bug
> Components: Static Type Checker
> Affects Versions: 2.4.12
> Reporter: Graeme Rocher
> Assignee: Paul King
>
> In order to get the GORM codebase to compile I had to make this change:
> https://github.com/grails/grails-data-mapping/commit/1ef850c496d13d8ca915b27e76b6bfdb4e27377e
> The code in question is:
> {code}
> /**
> * Sets multipart values within the request body
> *
> * @param name The name of the multipart
> * @param value The value of the multipart
> */
> void setProperty(String name, value) {
> if (value instanceof File) {
> value = new FileSystemResource(value)
> }
> else if (value instanceof URL) {
> value = new UrlResource(value)
> }
> else if (value instanceof InputStream) {
> value = new InputStreamResource(value)
> }
> else if (value instanceof GString) {
> value = value.toString()
> }
> if( mvm[name] ) {
> mvm[name].add value
> }
> else {
> mvm.put(name, [value]) // <--- FAILS COMPILATION HERE
> }
> }
> {code}
> No matter what I tried I could not get it into to compile. The method accepts
> `put(String, List<Object>)` but fails compilation with:
> {code}
> RequestCustomizer.groovy: 392: [Static type checking] - Cannot call
> org.springframework.util.MultiValueMap <String, Object>#put(java.lang.String,
> java.lang.Object) with arguments [java.lang.String, java.util.List
> <java.lang.String>]
> @ line 392, column 13.
> mvm.put(name, [value])
> ^
> {code}
> Altering the code to:
> {code}
> List<Object> values = [value]
> mvm.put(name, values)
> {code}
> Fails with:
> {code}
> RequestCustomizer.groovy: 392: [Static type checking] - Incompatible generic
> argument types. Cannot assign java.util.List <java.lang.String> to:
> java.util.List <Object>
> @ line 392, column 35.
> List<Object> values = [value]
> ^
> RequestCustomizer.groovy: 393: [Static type checking] - Cannot call
> org.springframework.util.MultiValueMap <String, Object>#put(java.lang.String,
> java.lang.Object) with arguments [java.lang.String, java.util.List
> <java.lang.String>]
> @ line 393, column 13.
> mvm.put(name, values)
> ^
> 2 errors
> {code}
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