Add test for KT-52782

It just demonstrates/fixate the current "broken" behavior in K1 that we unfortunately have and that is fixed in K2
2022-08-24 12:22:18 +02:00
parent 01f567a16d
commit 490382b77f
8 changed files with 152 additions and 0 deletions
@@ -0,0 +1,62 @@
+// SKIP_TXT
+// FILE: Foo.java
+public abstract class Foo<K extends Bar<? extends Foo<K>>> {
+    abstract String getTest();
+}
+
+// FILE: Bar.java
+public abstract class Bar<T extends Foo<? extends Bar<T>>> {}
+
+// FILE: main.kt
+
+fun <F : Bar<out Foo<F>>> Foo<F>.bar() {}
+
+fun box(foo: Foo<*>) {
+    // How inference for the `foo.bar()` call works
+    //
+    // X = Captured(*)
+    // Foo<X> <: Foo<Fv> => X = Fv => NewBound(X <: Fv), NewBound(Fv <: X)
+    //
+    // Incorporation 1:
+    // X <: Fv && Fv <: Bar<out Foo<Fv>> => X <: Bar<out Foo<Fv>>
+    // X has one supertype – Bar<out Foo<X>> ~ Bar<Y> where Y = Captured(out Foo<X>)
+    // X <: Bar<out Foo<Fv>> => Bar<Y> <: Bar<out Foo<Fv>> =>
+    // Y <: Foo<Fv>
+    // Y has two supertypes --> (Foo<out Bar<Y>>, Foo<X>)
+    // Let Z be a captured type in Foo<out Bar<Y>>
+    // Foo<Z> <: Foo<Fv> => Z = Fv =>
+    // But since Z is captured from subtyping we run approximation over it resulting to
+    // Z ~ Bar<out Foo<*>>
+    // NewBound(Bar<out Foo<*>> <: Fv)
+    //
+    // But since Fv <: X, Bar<out Foo<*>> should be a subtype of X, but it is not :(
+    //
+    // Note the problematic part is when Y has two supertypes
+    // And we just check only first one one the second one would work
+    // In K2, it's covered by fork-points, see https://youtrack.jetbrains.com/issue/KT-50401 and org.jetbrains.kotlin.resolve.calls.inference.components.ConstraintInjector.TypeCheckerStateForConstraintInjector.runForkingPoint
+
+
+    // Without approximation (just theoretically what would happen if we didn't approximated FROM_SUBTYPING captured types).
+    // Actually, it's not really relevant but just in case someone need it.
+    //
+    // X = Captured(*)
+    // Foo<X> <: Foo<Fv> => X = Fv => NewBound(X <: Fv), NewBound(Fv <: X)
+    //
+    // Incorporation 1:
+    // X <: Fv && Fv <: Bar<out Foo<Fv>> => X <: Bar<out Foo<Fv>>
+    // X has one supertype – Bar<out Foo<X>> ~ Bar<Y> where Y = Captured(out Foo<X>)
+    // X <: Bar<out Foo<Fv>> => Bar<Y> <: Bar<out Foo<Fv>> =>
+    // Y <: Foo<Fv>
+    // Y has two supertypes --> (Foo<out Bar<Y>>, Foo<X>)
+    // Let Z be a captured type in Foo<out Bar<Y>>
+    // Foo<Z> <: Foo<Fv> => Z = Fv => NewBound(Z <: Fv)
+    //
+    // Incorporation 2:
+    // Z <: Fv && Fv <: Bar<out Foo<Fv>> => Z <: Bar<out Foo<Fv>>
+    // Z has two supertypes --> (Bar<out Foo<Z>>, Bar<Y>)
+    // ... went into recursion
+
+    foo.bar()
+
+    foo.test
+}
@@ -0,0 +1,62 @@
+// SKIP_TXT
+// FILE: Foo.java
+public abstract class Foo<K extends Bar<? extends Foo<K>>> {
+    abstract String getTest();
+}
+
+// FILE: Bar.java
+public abstract class Bar<T extends Foo<? extends Bar<T>>> {}
+
+// FILE: main.kt
+
+fun <F : Bar<out Foo<F>>> Foo<F>.bar() {}
+
+fun box(foo: Foo<*>) {
+    // How inference for the `foo.bar()` call works
+    //
+    // X = Captured(*)
+    // Foo<X> <: Foo<Fv> => X = Fv => NewBound(X <: Fv), NewBound(Fv <: X)
+    //
+    // Incorporation 1:
+    // X <: Fv && Fv <: Bar<out Foo<Fv>> => X <: Bar<out Foo<Fv>>
+    // X has one supertype – Bar<out Foo<X>> ~ Bar<Y> where Y = Captured(out Foo<X>)
+    // X <: Bar<out Foo<Fv>> => Bar<Y> <: Bar<out Foo<Fv>> =>
+    // Y <: Foo<Fv>
+    // Y has two supertypes --> (Foo<out Bar<Y>>, Foo<X>)
+    // Let Z be a captured type in Foo<out Bar<Y>>
+    // Foo<Z> <: Foo<Fv> => Z = Fv =>
+    // But since Z is captured from subtyping we run approximation over it resulting to
+    // Z ~ Bar<out Foo<*>>
+    // NewBound(Bar<out Foo<*>> <: Fv)
+    //
+    // But since Fv <: X, Bar<out Foo<*>> should be a subtype of X, but it is not :(
+    //
+    // Note the problematic part is when Y has two supertypes
+    // And we just check only first one one the second one would work
+    // In K2, it's covered by fork-points, see https://youtrack.jetbrains.com/issue/KT-50401 and org.jetbrains.kotlin.resolve.calls.inference.components.ConstraintInjector.TypeCheckerStateForConstraintInjector.runForkingPoint
+
+
+    // Without approximation (just theoretically what would happen if we didn't approximated FROM_SUBTYPING captured types).
+    // Actually, it's not really relevant but just in case someone need it.
+    //
+    // X = Captured(*)
+    // Foo<X> <: Foo<Fv> => X = Fv => NewBound(X <: Fv), NewBound(Fv <: X)
+    //
+    // Incorporation 1:
+    // X <: Fv && Fv <: Bar<out Foo<Fv>> => X <: Bar<out Foo<Fv>>
+    // X has one supertype – Bar<out Foo<X>> ~ Bar<Y> where Y = Captured(out Foo<X>)
+    // X <: Bar<out Foo<Fv>> => Bar<Y> <: Bar<out Foo<Fv>> =>
+    // Y <: Foo<Fv>
+    // Y has two supertypes --> (Foo<out Bar<Y>>, Foo<X>)
+    // Let Z be a captured type in Foo<out Bar<Y>>
+    // Foo<Z> <: Foo<Fv> => Z = Fv => NewBound(Z <: Fv)
+    //
+    // Incorporation 2:
+    // Z <: Fv && Fv <: Bar<out Foo<Fv>> => Z <: Bar<out Foo<Fv>>
+    // Z has two supertypes --> (Bar<out Foo<Z>>, Bar<Y>)
+    // ... went into recursion
+
+    foo.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>bar<!>()
+
+    foo.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>test<!>
+}
@@ -30,6 +30,8 @@ fun String.asFsdAddress(): String {
 fun box(): String {
    val state = Test().state
    if (state is GoBuildingRunningState<*>) {
+        // Actually, that code is valid and met at IJ, but unfortunately it was broken since 1.7.0
+        // See KT-52782 and testData/diagnostics/tests/inference/capturedTypes/kt52782.kt
        state.buildingWorkingDirectory.asFsdAddress()
    }
    return "OK"
@@ -30,6 +30,8 @@ fun String.asFsdAddress(): String {
 fun box(): String {
    val state = Test().state
    if (state is GoBuildingRunningState<*>) {
+        // Actually, that code is valid and met at IJ, but unfortunately it was broken since 1.7.0
+        // See KT-52782 and testData/diagnostics/tests/inference/capturedTypes/kt52782.kt
        state.<!UNRESOLVED_REFERENCE_WRONG_RECEIVER!>buildingWorkingDirectory<!>.<!DEBUG_INFO_MISSING_UNRESOLVED!>asFsdAddress<!>()
    }
    return "OK"