Tianyu Geng
c7272f6986
Currently DFA does not set "definitely equal to null" for access to variables that got assigned `null`. For example, FIR should mark the following line as SENSELESS_COMPARISON due to `s = null` above. https://github.com/JetBrains/kotlin/blob/d1531f9cdd5852352c0133198706125dc63b6007/compiler/testData/diagnostics/tests/smartCasts/alwaysNull.fir.kt#L6 The problem is at https://github.com/JetBrains/kotlin/blob/7e9f27436a77de1c76e3705da7aa1fbe8938336b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/dfa/FirDataFlowAnalyzer.kt#L1104 For null assignment, ideally the type should be `Nothing?`. This is addressed in a followup commit instead.
57 lines
1.2 KiB
Kotlin
Vendored
57 lines
1.2 KiB
Kotlin
Vendored
// !LANGUAGE: +AllowContractsForCustomFunctions +UseReturnsEffect
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// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
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// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
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import kotlin.contracts.*
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fun nullWhenNull(x: Int?): Int? {
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contract {
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returnsNotNull() implies (x != null)
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}
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return x?.inc()
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}
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fun testNullWhenNull(x: Int?) {
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if (nullWhenNull(x) == null) {
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x<!UNSAFE_CALL!>.<!>dec()
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}
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else {
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x.dec()
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}
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if (nullWhenNull(x) != null) {
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x.dec()
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}
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else {
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x<!UNSAFE_CALL!>.<!>dec()
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}
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x<!UNSAFE_CALL!>.<!>dec()
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}
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// NB. it is the same function as `nullWhenNull`, but annotations specifies other facet of the function behaviour
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fun notNullWhenNotNull (x: Int?): Int? {
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contract {
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returns(null) implies (x == null)
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}
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return x?.inc()
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}
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fun testNotNullWhenNotNull (x: Int?) {
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if (notNullWhenNotNull(x) == null) {
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<!SENSELESS_COMPARISON!>x == null<!>
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}
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else {
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x<!UNSAFE_CALL!>.<!>dec()
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}
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if (notNullWhenNotNull(x) != null) {
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x<!UNSAFE_CALL!>.<!>dec()
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}
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else {
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<!SENSELESS_COMPARISON!>x == null<!>
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}
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x<!UNSAFE_CALL!>.<!>dec()
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}
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