Thodoris Sotiropoulos created GROOVY-11477:
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Summary: assignments in closures may lead to CCE when flow typing
is enabled
Key: GROOVY-11477
URL: https://issues.apache.org/jira/browse/GROOVY-11477
Project: Groovy
Issue Type: Bug
Components: Static Type Checker
Reporter: Thodoris Sotiropoulos
This is related to 11471.
I have the following program
{code:java}
class Test {
public static void main(String[] args) {
def x = 1
Closure m = null
if (true) {
m = {x = ""}
}
x = 1
m()
Integer y = x
y.intValue()
}
} {code}
h3. Actual behavior
The code compiles, but I get
{code:java}
Exception in thread "main"
org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast
object '' with class 'java.lang.String' to class 'java.lang.Integer'
at
org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.castToNumber(DefaultTypeTransformation.java:177)
at
org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.continueCastOnNumber(DefaultTypeTransformation.java:294)
at
org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.castToType(DefaultTypeTransformation.java:248)
at
org.codehaus.groovy.vmplugin.v8.IndyInterface.fromCache(IndyInterface.java:336)
at Test.main(test.groovy:10)
{code}
h3. Expected behavior
The code should have been rejected.
h3. Notes
Notably, in this slightly modified version of the above program, the type
checkers behaves as expected.
{code:java}
class Test {
public static void main(String[] args) {
def x = 1
Closure m = null
if (true) {
m = {x = ""}
}
x = 1
m()
x.intValue()
}
} {code}
{code:java}
test.groovy: 10: [Static type checking] - The closure shared variable "x" has
been assigned with various types and the method intValue() does not exist in
the lowest upper bound of those types: (java.io.Serializable &
java.lang.Comparable). In general, this style of variable reuse is a bad
practice because the compiler cannot determine safely what is the type of the
variable at the moment of the call in a multi-threaded context.
@ line 10, column 5.
x.intValue()
^1 error
{code}
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