[jira] [Created] (GROOVY-8255) Odd problems with flow typing and generics in Groovy 2.4.12+

["Graeme Rocher (JIRA)" <ji...@apache.org>]

Graeme Rocher created GROOVY-8255:
-------------------------------------

             Summary: 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
    Affects Versions: 2.4.12
            Reporter: Graeme Rocher


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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