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Posted to notifications@groovy.apache.org by "Thodoris Sotiropoulos (Jira)" <ji...@apache.org> on 2022/05/13 13:38:00 UTC
[jira] [Created] (GROOVY-10623) Type mismatch when encountering unconditional flow typing and null
Thodoris Sotiropoulos created GROOVY-10623:
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Summary: Type mismatch when encountering unconditional flow typing and null
Key: GROOVY-10623
URL: https://issues.apache.org/jira/browse/GROOVY-10623
Project: Groovy
Issue Type: Bug
Components: Static Type Checker
Reporter: Thodoris Sotiropoulos
I don't know if this is a bug or a feature
I have the following program
{code}
class A {}
class Test {
void test() {
def x = new A() // type of x is A
x = null; // type of x becomes Object
A y = x
}
void test2() {
def x = new A()
if (true) {
x = null
}
A y = x // compiles as expected
}
}
{code}
h3. Actual behavior
{code}
org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
test.groovy: 9: [Static type checking] - Cannot assign value of type java.lang.Object to variable of type A
@ line 9, column 11.
A y = x
^
1 error
{code}
h3. Expected behavior
Compile successfully
The issue here is that when the compiler encounters a `null` assignment to a `def` variable, it changes the previously-inferred type of the variable to `Object`. Probably, this is not necessary as `null` is assignable to any type.
Tested against master (commit: ee12bb52381e8f0583c61fc25d43de1f55b80a87)
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