diff --git a/idea/testData/checker/infos/Autocasts.jet b/idea/testData/checker/infos/Autocasts.jet
index 7cf18aadd48..062b26b75a2 100644
--- a/idea/testData/checker/infos/Autocasts.jet
+++ b/idea/testData/checker/infos/Autocasts.jet
@@ -1,4 +1,4 @@
-<info>open</info> class A() {
+<info descr="null">open</info> class A() {
   fun foo() {}
 }
 
@@ -9,25 +9,25 @@ class B() : A() {
 fun f9() {
   val a : A?
   a?.foo()
-  a?.<error>bar</error>()
+  a?.<error descr="Unresolved reference: bar">bar</error>()
   if (a is B) {
     <info descr="Automatically cast to B">a</info>.bar()
-    a.foo()
+    <info descr="Automatically cast to A">a</info>.foo()
   }
   a?.foo()
-  a?.<error>bar</error>()
+  a?.<error descr="Unresolved reference: bar">bar</error>()
   if (!(a is B)) {
-    a?.<error>bar</error>()
+    a?.<error descr="Unresolved reference: bar">bar</error>()
     a?.foo()
   }
   if (!(a is B) || <info descr="Automatically cast to B">a</info>.bar() == ()) {
-      a?.<error>bar</error>()
+      a?.<error descr="Unresolved reference: bar">bar</error>()
   }
   if (!(a is B)) {
     return;
   }
   <info descr="Automatically cast to B">a</info>.bar()
-  a.foo()
+  <info descr="Automatically cast to A">a</info>.foo()
 }
 
 fun f10() {
@@ -47,19 +47,17 @@ class C() : A() {
 }
 
 fun f10(a : A?) {
-  if (a is B) {
     if (a is C) {
       <info descr="Automatically cast to C">a</info>.bar();
     }
-  }
 }
 
 fun f11(a : A?) {
   when (a) {
     is B => <info descr="Automatically cast to B">a</info>.bar()
-    is A => a.foo()
-    is Any => a.foo()
-    is Any? => a.<error>bar</error>()
+    is A => <info descr="Automatically cast to A">a</info>.foo()
+    is Any => <info descr="Automatically cast to A">a</info>.foo()
+    is Any? => a.<error descr="Unresolved reference: bar">bar</error>()
     else => a?.foo()
   }
 }
@@ -67,21 +65,21 @@ fun f11(a : A?) {
 fun f12(a : A?) {
   when (a) {
     is B => <info descr="Automatically cast to B">a</info>.bar()
-    is A => a.foo()
-    is Any => a.foo();
-    is Any? => a.<error>bar</error>()
-    is val c : <error>B</error> => c.foo()
+    is A => <info descr="Automatically cast to A">a</info>.foo()
+    is Any => <info descr="Automatically cast to A">a</info>.foo();
+    is Any? => a.<error descr="Unresolved reference: bar">bar</error>()
+    is val c : <error descr="[TYPE_MISMATCH_IN_BINDING_PATTERN] B must be a supertype of A?. Use is to match against B">B</error> => c.foo()
     is val c is C => <info descr="Automatically cast to C">c</info>.bar()
     is val c is C => <info descr="Automatically cast to C">a</info>.bar()
     else => a?.foo()
   }
 
   if (a is val b) {
-    a?.<error>bar</error>()
+    a?.<error descr="Unresolved reference: bar">bar</error>()
     b?.foo()
   }
   if (a is val b is B) {
-    b.foo()
+    <info descr="Automatically cast to A">b</info>.foo()
     <info descr="Automatically cast to B">a</info>.bar()
     <info descr="Automatically cast to B">b</info>.bar()
   }
@@ -89,41 +87,41 @@ fun f12(a : A?) {
 
 fun f13(a : A?) {
   if (a is val c is B) {
-    c.foo()
+    <info descr="Automatically cast to A">c</info>.foo()
     <info descr="Automatically cast to B">c</info>.bar()
   }
   else {
     a?.foo()
-    <error>c</error>.bar()
+    <error descr="Unresolved reference: c">c</error>.bar()
   }
 
   a?.foo()
   if (!(a is val c is B)) {
     a?.foo()
-    <error>c</error>.bar()
+    <error descr="Unresolved reference: c">c</error>.bar()
   }
   else {
-    a.foo()
-    <error>c</error>.bar()
+    <info descr="Automatically cast to A">a</info>.foo()
+    <error descr="Unresolved reference: c">c</error>.bar()
   }
 
   a?.foo()
-  if (a is val c is B && a.foo() == () && <info descr="Automatically cast to B">c</info>.bar() == ()) {
-    c.foo()
+  if (a is val c is B && <info descr="Automatically cast to A">a</info>.foo() == () && <info descr="Automatically cast to B">c</info>.bar() == ()) {
+    <info descr="Automatically cast to A">c</info>.foo()
     <info descr="Automatically cast to B">c</info>.bar()
   }
   else {
     a?.foo()
-    <error>c</error>.bar()
+    <error descr="Unresolved reference: c">c</error>.bar()
   }
 
   if (!(a is val c is B) || !(a is val x is C)) {
-    <error>x</error>
-    <error>c</error>
+    <error descr="Unresolved reference: x">x</error>
+    <error descr="Unresolved reference: c">c</error>
   }
   else {
-    <error>x</error>
-    <error>c</error>
+    <error descr="Unresolved reference: x">x</error>
+    <error descr="Unresolved reference: c">c</error>
   }
 
   if (!(a is val c is B) || !(a is val c is C)) {
@@ -131,38 +129,38 @@ fun f13(a : A?) {
 
   if (!(a is val c is B)) return
   <info descr="Automatically cast to B">a</info>.bar()
-  <error>c</error>.foo()
-  <error>c</error>.bar()
+  <error descr="Unresolved reference: c">c</error>.foo()
+  <error descr="Unresolved reference: c">c</error>.bar()
 }
 
 fun f14(a : A?) {
   while (!(a is val c is B)) {
   }
   <info descr="Automatically cast to B">a</info>.bar()
-  <error>c</error>.bar()
+  <error descr="Unresolved reference: c">c</error>.bar()
 }
 fun f15(a : A?) {
   do {
   } while (!(a is val c is B))
   <info descr="Automatically cast to B">a</info>.bar()
-  <error>c</error>.bar()
+  <error descr="Unresolved reference: c">c</error>.bar()
 }
 
 fun getStringLength(obj : Any) : Char? {
   if (obj !is String)
     return null
-  return <info>obj</info>.get(0) // no cast to String is needed
+  return <info descr="Automatically cast to String">obj</info>.get(0) // no cast to String is needed
 }
 
 fun toInt(i: Int?): Int = if (i != null) <info descr="Automatically cast to Int">i</info> else 0
 fun illegalWhenBody(a: Any): Int = when(a) {
     is Int => <info descr="Automatically cast to Int">a</info>
-    is String => <error>a</error>
+    is String => <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any but Int was expected">a</error>
 }
 fun illegalWhenBlock(a: Any): Int {
     when(a) {
         is Int => return <info descr="Automatically cast to Int">a</info>
-        is String => return <error>a</error>
+        is String => return <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any but Int was expected">a</error>
     }
 }
 fun declarations(a: Any?) {
@@ -188,17 +186,17 @@ fun vars(a: Any?) {
 }
 fun tuples(a: Any?) {
     if (a != null) {
-        val s: (Any, String) = (<info descr="Automatically cast to Any">a</info>, <error>a</error>)
+        val s: (Any, String) = (<info descr="Automatically cast to Any">a</info>, <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any? but String was expected">a</error>)
     }
     if (a is String) {
-        val s: (Any, String) = (<info descr="Automatically cast to Any">a</info>, <info descr="Automatically cast to String">a</info>)
+        val s: (Any, String) = (<info descr="Automatically cast to String">a</info>, <info descr="Automatically cast to String">a</info>)
     }
-    fun illegalTupleReturnType(): (Any, String) = (<error>a</error>, <error>a</error>)
+    fun illegalTupleReturnType(): (Any, String) = (<error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any? but Any was expected">a</error>, <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any? but String was expected">a</error>)
     if (a is String) {
-        fun legalTupleReturnType(): (Any, String) = (<info descr="Automatically cast to Any">a</info>, <info descr="Automatically cast to String">a</info>)
+        fun legalTupleReturnType(): (Any, String) = (<info descr="Automatically cast to String">a</info>, <info descr="Automatically cast to String">a</info>)
     }
-    val illegalFunctionLiteral: Function0<Int> = <error>{ <error>a</error> }</error>
-    val illegalReturnValueInFunctionLiteral: Function0<Int> = { (): Int => <error>a</error> }
+    val illegalFunctionLiteral: Function0<Int> = <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Function0<Any?> but Function0<Int> was expected">{ <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any? but Int was expected">a</error> }</error>
+    val illegalReturnValueInFunctionLiteral: Function0<Int> = { (): Int => <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any? but Int was expected">a</error> }
 
     if (a is Int) {
         val legalFunctionLiteral: Function0<Int> = { <info descr="Automatically cast to Int">a</info> }
@@ -213,43 +211,43 @@ fun returnFunctionLiteral(a: Any?): Function0<Int> =
     if (a is Int) { (): Int => <info descr="Automatically cast to Int">a</info> }
     else { () => 1 }
 
-fun illegalTupleReturnType(a: Any): (Any, String) = (a, <error>a</error>)
+fun illegalTupleReturnType(a: Any): (Any, String) = (a, <error descr="[TYPE_MISMATCH] Type mismatch: inferred type is Any but String was expected">a</error>)
 
 fun declarationInsidePattern(x: (Any, Any)): String = when(x) { is (val a is String, *) => <info descr="Automatically cast to String">a</info>; else => "something" }
 
 fun mergeAutocasts(a: Any?) {
   if (a is String || a is Int) {
-    a.<error>compareTo</error>("")
+    a.<error descr="Unresolved reference: compareTo">compareTo</error>("")
     a.toString()
   }
   if (a is Int || a is String) {
-    a.<error>compareTo</error>("")
+    a.<error descr="Unresolved reference: compareTo">compareTo</error>("")
   }
   when (a) {
-    is String, is Any => a.<error>compareTo</error>("")
+    is String, is Any => a.<error descr="Unresolved reference: compareTo">compareTo</error>("")
   }
   if (a is String && a is Any) {
     val i: Int = <info descr="Automatically cast to String">a</info>.compareTo("")
   }
   if (a is String && <info descr="Automatically cast to String">a</info>.compareTo("") == 0) {}
-  if (a is String || a.<error>compareTo</error>("") == 0) {}
+  if (a is String || a.<error descr="Unresolved reference: compareTo">compareTo</error>("") == 0) {}
 }
 
 //mutability
 fun f(): String {
     var a: Any = 11
     if (a is String) {
-        val i: String = <error>a</error>
-        <error>a</error>.compareTo("f")
-        val f: Function0<String> = { <error>a</error> }
-        return <error>a</error>
+        val i: String = <error descr="[AUTOCAST_IMPOSSIBLE] Automatic cast to String is impossible, because a could have changed since the is-check">a</error>
+        <error descr="[AUTOCAST_IMPOSSIBLE] Automatic cast to String is impossible, because a could have changed since the is-check">a</error>.compareTo("f")
+        val f: Function0<String> = { <error descr="[AUTOCAST_IMPOSSIBLE] Automatic cast to String is impossible, because a could have changed since the is-check">a</error> }
+        return <error descr="[AUTOCAST_IMPOSSIBLE] Automatic cast to String is impossible, because a could have changed since the is-check">a</error>
     }
     return ""
 }
 
 fun foo(var a: Any): Int {
     if (a is Int) {
-        return <error>a</error>
+        return <error descr="[AUTOCAST_IMPOSSIBLE] Automatic cast to Int is impossible, because a could have changed since the is-check">a</error>
     }
     return 1
 }
\ No newline at end of file
diff --git a/idea/testData/checkerWithErrorTypes/full/When.jet b/idea/testData/checkerWithErrorTypes/full/When.jet
index f8612546d1c..7f53fb38c9d 100644
--- a/idea/testData/checkerWithErrorTypes/full/When.jet
+++ b/idea/testData/checkerWithErrorTypes/full/When.jet
@@ -1,3 +1,5 @@
+fun Int.foo() : Boolean = true
+
 fun foo() : Int {
     val s = ""
     val x = 1
@@ -17,7 +19,8 @@ fun foo() : Int {
       else => 1
     }
     return when (<!USELESS_ELVIS!>x<!>?:null) {
-      <!UNSAFE_CALL!>.<!>equals(1) => 1
+      <!UNSAFE_CALL!>.<!>foo() => 1
+      .equals(1) => 1
       ?.equals(1).equals(2) => 1
     }
 }
diff --git a/idea/testData/checkerWithErrorTypes/full/infos/Autocasts.jet b/idea/testData/checkerWithErrorTypes/full/infos/Autocasts.jet
index ff7066a34f5..a3cf2976f1f 100644
--- a/idea/testData/checkerWithErrorTypes/full/infos/Autocasts.jet
+++ b/idea/testData/checkerWithErrorTypes/full/infos/Autocasts.jet
@@ -47,11 +47,9 @@ class C() : A() {
 }
 
 fun f10(a : A?) {
-  if (a is B) {
     if (a is C) {
       a.bar();
     }
-  }
 }
 
 fun f11(a : A?) {