If property call receiver is something real (like another property or a
function call), then it should not be shortened because the semantics
might change
^KTIJ-25232 Fixed
The existing K2 reference shortener collects all the PSI elements to
shorten. As a result, it possibly shortens duplicated PSI elements. For
example,
```
// FILE: main.kt
package a.b.c
fun test(n: Int) {
return if (<expr>x.y.z.Outer.Inner.VALUE0 > x.y.z.Outer.Inner.VALUE1</expr>) 1
else n
}
// FILE: values.kt
package x.y.z
class Outer {
object Inner {
val VALUE0 = 13
val VALUE1 = 17
}
}
```
for the above code, the existing K2 reference shortener tried to shorten
- x.y.z.Outer.Inner -> Inner
- x.y.z.Outer.Inner.VALUE0 -> VALUE0
- x.y.z.Outer.Inner -> Inner
- x.y.z.Outer.Inner.VALUE1 -> VALUE1
`x.y.z.Outer.Inner` is included in the list to shorten twice.
When it actually shortens the PSI elements, it shortens only
- x.y.z.Outer.Inner.VALUE0 -> VALUE0
- x.y.z.Outer.Inner.VALUE1 -> VALUE1
but it imports all of
- x.y.z.Outer.Inner
- x.y.z.Outer.Inner.VALUE0
- x.y.z.Outer.Inner.VALUE1
As a result, it has unnecessary additional import directives.
This commit fixes the issue by avoiding duplicated shortening for a
single PSI element.
Those scopes always contain all nested classifiers,
while only some of them are available without
explicit import. There are other, more reliable
scopes (like FirNestedClassifierScopeWithSubstitution)
which are stricter about which classifiers
they recognise as valid
^KTIJ-24684 Fixed
^KTIJ-24662 Fixed
For the following example, when we run the reference shortener, it
drops `a.b.c` qualifier, because it matches "FOURTH".
```
package a.b.c
fun <T, E, D> foo(a: T, b: E, c: D) = a.hashCode() + b.hashCode() + c.hashCode() // FIRST
fun <E> E.foo() = hashCode() // SECOND
object Receiver {
fun <T, E, D> foo(a: T, b: E, c: D) = a.hashCode() + b.hashCode() + c.hashCode() // THIRD
fun foo(a: Int, b: Boolean, c: String) = a.hashCode() + b.hashCode() + c.hashCode() // FOURTH
fun test(): Int {
fun foo(a: Int, b: Boolean, c: Int) = a + b.hashCode() + c // FIFTH
return <expr>a.b.c.foo(1, false, "bar")</expr>
}
}
```
As shown in the above example, when SHORTEN_IF_ALEADY_IMPORTED option is
given from a user, the reference shortener has to check whether it can
drop the qualifier without changing the referenced symbol and if it is
possible to do that without adding a new import directive, it deletes
the qualifier.
It needs two steps:
1. Collect all candidate symbols matching the signature e.g., function
arguments / type arguments
2. Determine whether the referenced symbol has the highest reference
priority when we drops the qualifier depending on scopes
This commit uses `AllCandidatesResolver(shorteningContext.analysisSession.useSiteSession).
getAllCandidates( .. fake FIR call/property-access ..)` for step1.
For step2, we use a heuristic based on scopes of candidates. If a
candidate symbol is under the same scope with the target expression, it
has a `FirLocalScope` which has the high priority. So when we have a
candidate under a `FirLocalScope` and the actual referenced symbol is
different from the candidate, we must avoid dropping its qualifier
because the shortening will change its semantics i.e., reference.
The order of scopes depending on their scope types is:
1. FirLocalScope
2. FirClassUseSiteMemberScope / FirNestedClassifierScope
3. FirExplicitSimpleImportingScope
4. FirPackageMemberScope
5. others
Note that for "others" the above rule can be wrong. Please update it if
you find other scopes that have a priority higher than the specified
scopes.
One of non-trivial parts is the priority among multiple
FirClassUseSiteMemberScope and FirNestedClassifierScope. They are
basically scopes for class declarations. We decide their priorities
based on the distance of class declaration from the target expression.
Note that we take a strict approach to reject all false positive. For
example, when we are not sure, we don't shorten it to avoid changing its
semantics.
TODO: One corner case is handling receivers. We have to update
```
private fun shortenIfAlreadyImported(
firQualifiedAccess: FirQualifiedAccess,
calledSymbol: FirCallableSymbol<*>,
expressionInScope: KtExpression,
): Boolean
```
The current implementation cannot handle the following example:
```
package foo
class Foo {
fun test() {
// It references FIRST. Removing `foo` lets it reference SECOND.
<caret>foo.myRun {
42
}
}
}
inline fun <R> myRun(block: () -> R): R = block() // FIRST
inline fun <T, R> T.myRun(block: T.() -> R): R = block() // SECOND
```
Tests related to TODO:
- analysis/analysis-api/testData/components/referenceShortener/referenceShortener/receiver2.kt
- analysis/analysis-api/testData/components/referenceShortener/referenceShortener/receiver3.kt
Ilya Kirillov