[FIR] Report empty intersection on responsible call

When reporting INFERRED_TYPE_VARIABLE_INTO_EMPTY_INTERSECTION, search
for a call to a declaration with the type parameter that got inferred
into an empty intersection inside the expression.

#KT-56377 Fixed

compiler/testData/diagnostics/tests/inference/coercionToUnit/afterBareReturn.fir.kt

@@ -0,0 +1,41 @@
+interface I
+open class C
+
+fun completed(): String = "..."
+
+fun <T> incomplete(): T = null!!
+
+fun <T : I> incompatibleI(): T = null!!
+fun <T : C> incompatibleC(): T = null!!
+
+val p = false
+
+fun expectUnit(x: Unit) = x
+
+fun test1() = run {
+    if (p) return@run
+    completed() // ok, not returned
+}
+
+fun test2() = run {
+    if (p) return@run
+    incomplete() // ? either uninferred T or Unit
+}
+
+fun test3() = run {
+    if (p) return@run
+    <!INFERRED_TYPE_VARIABLE_INTO_POSSIBLE_EMPTY_INTERSECTION!>incompatibleI<!>() // ? either uninferred T or error (Unit </: I)
+}
+
+fun test4() = run {
+    if (p) return@run
+    <!INFERRED_TYPE_VARIABLE_INTO_EMPTY_INTERSECTION_WARNING!>incompatibleC<!>() // ? either uninferred T or error (Unit </: C)
+}
+
+fun main() {
+    // all ok
+    expectUnit(test1())
+    expectUnit(test2())
+    expectUnit(test3())
+    expectUnit(test4())
+}

compiler/testData/diagnostics/tests/inference/coercionToUnit/afterBareReturn.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 interface I
 open class C
 

compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/kt49661.fir.kt

@@ -0,0 +1,12 @@
+// !LANGUAGE: -ForbidInferringTypeVariablesIntoEmptyIntersection
+// RENDER_DIAGNOSTICS_FULL_TEXT
+open class Foo
+inline fun <reified T : Foo> g(): T? = null
+
+inline fun <R> f(block: ()->R?): R? {
+    return block()
+}
+
+fun main() {
+    f<Int> { <!INFERRED_TYPE_VARIABLE_INTO_EMPTY_INTERSECTION_WARNING!>g<!>() }
+}

compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/kt49661.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !LANGUAGE: -ForbidInferringTypeVariablesIntoEmptyIntersection
 // RENDER_DIAGNOSTICS_FULL_TEXT
 open class Foo

compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/nullableEmptyIntersection.fir.kt

@@ -0,0 +1,8 @@
+// !LANGUAGE: -ForbidInferringTypeVariablesIntoEmptyIntersection
+fun <T : <!FINAL_UPPER_BOUND!>String<!>> g(): T? = null
+
+fun <R> f(block: () -> R?): R? = block()
+
+fun main() {
+    f<Int> { <!INFERRED_TYPE_VARIABLE_INTO_EMPTY_INTERSECTION_WARNING!>g<!>() /* OK, g() is inferred into {Int & String}? */ }
+}

compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/nullableEmptyIntersection.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !LANGUAGE: -ForbidInferringTypeVariablesIntoEmptyIntersection
 fun <T : <!FINAL_UPPER_BOUND!>String<!>> g(): T? = null