[NI] Select variable with proper non-trivial constraint first

compiler/testData/ir/irText/regressions/newInference/fixationOrder1.kt

@@ -0,0 +1,13 @@
+fun <X, Y> foo(): (X) -> Y = TODO()
+
+interface Inv2<A, B>
+
+fun <T, R> check(x: T, y: R, f: (T) -> R): Inv2<T, R> = TODO()
+
+fun test() = check("", 1, foo())
+
+fun box(): String {
+    val x: Inv2<String, Int> = test()
+
+    return "OK"
+}

compiler/testData/ir/irText/regressions/newInference/fixationOrder1.txt

@@ -0,0 +1,44 @@
+FILE /fixationOrder1.kt
+  FUN public fun <X, Y> foo(): (X) -> Y
+    TYPE_PARAMETER <X>
+    TYPE_PARAMETER <Y>
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='foo(): (X) -> Y'
+        CALL 'TODO(): Nothing' type=kotlin.Nothing origin=null
+  CLASS INTERFACE Inv2
+    $this: VALUE_PARAMETER this@Inv2: Inv2<A, B>
+    TYPE_PARAMETER <A>
+    TYPE_PARAMETER <B>
+    FUN FAKE_OVERRIDE public open override fun equals(other: kotlin.Any?): kotlin.Boolean
+      $this: VALUE_PARAMETER this@Any: Any
+      VALUE_PARAMETER value-parameter other: kotlin.Any?
+    FUN FAKE_OVERRIDE public open override fun hashCode(): kotlin.Int
+      $this: VALUE_PARAMETER this@Any: Any
+    FUN FAKE_OVERRIDE public open override fun toString(): kotlin.String
+      $this: VALUE_PARAMETER this@Any: Any
+  FUN public fun <T, R> check(x: T, y: R, f: (T) -> R): Inv2<T, R>
+    TYPE_PARAMETER <T>
+    TYPE_PARAMETER <R>
+    VALUE_PARAMETER value-parameter x: T
+    VALUE_PARAMETER value-parameter y: R
+    VALUE_PARAMETER value-parameter f: (T) -> R
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='check(T, R, (T) -> R): Inv2<T, R>'
+        CALL 'TODO(): Nothing' type=kotlin.Nothing origin=null
+  FUN public fun test(): Inv2<kotlin.String, kotlin.Int>
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='test(): Inv2<String, Int>'
+        CALL 'check(String, Int, (String) -> Int): Inv2<String, Int>' type=Inv2<kotlin.String, kotlin.Int> origin=null
+          <T>: String
+          <R>: Int
+          x: CONST String type=kotlin.String value=''
+          y: CONST Int type=kotlin.Int value='1'
+          f: CALL 'foo(): (String) -> Int' type=(kotlin.String) -> kotlin.Int origin=null
+            <X>: String
+            <Y>: Int
+  FUN public fun box(): kotlin.String
+    BLOCK_BODY
+      VAR val x: Inv2<kotlin.String, kotlin.Int>
+        CALL 'test(): Inv2<String, Int>' type=Inv2<kotlin.String, kotlin.Int> origin=null
+      RETURN type=kotlin.Nothing from='box(): String'
+        CONST String type=kotlin.String value='OK'

compiler/testData/ir/irText/regressions/newInference/fixationOrder2.kt

@@ -0,0 +1,3 @@
+fun <X, Y, Z> foo(f: (Y) -> Z, g: (X) -> Y, x: X): Z = f(g(x))
+
+fun test() = foo({ it + 1 }, { it.length }, "")

compiler/testData/ir/irText/regressions/newInference/fixationOrder2.txt

@@ -0,0 +1,40 @@
+FILE /fixationOrder2.kt
+  FUN public fun <X, Y, Z> foo(f: (Y) -> Z, g: (X) -> Y, x: X): Z
+    TYPE_PARAMETER <X>
+    TYPE_PARAMETER <Y>
+    TYPE_PARAMETER <Z>
+    VALUE_PARAMETER value-parameter f: (Y) -> Z
+    VALUE_PARAMETER value-parameter g: (X) -> Y
+    VALUE_PARAMETER value-parameter x: X
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='foo((Y) -> Z, (X) -> Y, X): Z'
+        CALL 'invoke(Y): Z' type=Z origin=INVOKE
+          $this: GET_VAR 'value-parameter f: (Y) -> Z' type=(Y) -> Z origin=VARIABLE_AS_FUNCTION
+          p1: CALL 'invoke(X): Y' type=Y origin=INVOKE
+            $this: GET_VAR 'value-parameter g: (X) -> Y' type=(X) -> Y origin=VARIABLE_AS_FUNCTION
+            p1: GET_VAR 'value-parameter x: X' type=X origin=null
+  FUN public fun test(): kotlin.Int
+    BLOCK_BODY
+      RETURN type=kotlin.Nothing from='test(): Int'
+        CALL 'foo((Int) -> Int, (String) -> Int, String): Int' type=kotlin.Int origin=null
+          <X>: String
+          <Y>: Int
+          <Z>: Int
+          f: BLOCK type=(kotlin.Int) -> kotlin.Int origin=LAMBDA
+            FUN LOCAL_FUNCTION_FOR_LAMBDA local final fun <anonymous>(it: kotlin.Int): kotlin.Int
+              VALUE_PARAMETER value-parameter it: kotlin.Int
+              BLOCK_BODY
+                RETURN type=kotlin.Nothing from='<anonymous>(Int): Int'
+                  CALL 'plus(Int): Int' type=kotlin.Int origin=PLUS
+                    $this: GET_VAR 'value-parameter it: Int' type=kotlin.Int origin=null
+                    other: CONST Int type=kotlin.Int value='1'
+            FUNCTION_REFERENCE '<anonymous>(Int): Int' type=(kotlin.Int) -> kotlin.Int origin=LAMBDA
+          g: BLOCK type=(kotlin.String) -> kotlin.Int origin=LAMBDA
+            FUN LOCAL_FUNCTION_FOR_LAMBDA local final fun <anonymous>(it: kotlin.String): kotlin.Int
+              VALUE_PARAMETER value-parameter it: kotlin.String
+              BLOCK_BODY
+                RETURN type=kotlin.Nothing from='<anonymous>(String): Int'
+                  CALL '<get-length>(): Int' type=kotlin.Int origin=GET_PROPERTY
+                    $this: GET_VAR 'value-parameter it: String' type=kotlin.String origin=null
+            FUNCTION_REFERENCE '<anonymous>(String): Int' type=(kotlin.String) -> kotlin.Int origin=LAMBDA
+          x: CONST String type=kotlin.String value=''