Paul King created GROOVY-12479:
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Summary: SC: receiver expression is not evaluated when it is used
to access a static field or call a static method
Key: GROOVY-12479
URL: https://issues.apache.org/jira/browse/GROOVY-12479
Project: Groovy
Issue Type: Bug
Reporter: Paul King
Under {{@CompileStatic}}, when a static field or static method is reached
through a receiver expression rather than a class name, the receiver expression
is never evaluated. Any side effects it has are silently lost. Dynamic Groovy
and {{@TypeChecked}} evaluate it, as Java does (JLS 15.11.1, 15.12.4.1: for a
static member the receiver expression is evaluated and the result discarded).
{code:groovy}
class K { static final String CONST = 'c'; static String stat() { 's' } }
class Probe {
static List log = []
static Class<Integer> pickClass() { log << 'pickClass'; Integer }
static K pickInstance() { log << 'pickInstance'; new K() }
}
@groovy.transform.CompileStatic
class CS {
static a() { Probe.pickClass().MAX_VALUE } // static field via
Class-typed expression
static b() { Probe.pickInstance().CONST } // static field via
instance-typed expression
static c() { Probe.pickInstance().stat() } // static method via
instance-typed expression
static d() { Probe.pickClass().valueOf(1) } // static method via
Class-typed expression
}
Probe.log.clear(); CS.a(); assert Probe.log == ['pickClass'] // fails: []
Probe.log.clear(); CS.b(); assert Probe.log == ['pickInstance'] // fails: []
Probe.log.clear(); CS.c(); assert Probe.log == ['pickInstance'] // fails: []
Probe.log.clear(); CS.d(); assert Probe.log == ['pickClass'] // fails: []
{code}
The values are correct in every case; only the evaluation of the receiver is
missing.
||Case||@CompileStatic||@TypeChecked||dynamic||
|{{pickClass().MAX_VALUE}}|not evaluated|evaluated|evaluated|
|{{pickInstance().CONST}}|not evaluated|evaluated|evaluated|
|{{pickInstance().stat()}}|not evaluated|-|-|
|{{pickClass().valueOf(1)}}|not evaluated|-|-|
Same behaviour in 4.0.32, 5.1.2, 6.0.0 and master.
*Expected:* the receiver expression is evaluated once, its value discarded, and
the static member accessed, so the static-compiled result matches dynamic
Groovy and Java.
*Workaround:* evaluate the expression separately (e.g. {{def c = pickClass();
c.MAX_VALUE}}), or access the member through the class name.
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