Local returns are only allowed with explicitly specified return types

This is a temporary limitation: otherwise type inference is having trouble to account for all the returned expressions.
 We will fix the inference and remove the limitation

compiler/testData/diagnostics/tests/functionLiterals/return/LocalAndNonLocalReturnInLambda.kt

@@ -1,7 +1,7 @@
 fun test2(a: Int) {
     (run @f{
       if (a > 0) <!RETURN_NOT_ALLOWED!>return<!>
-      return@f 1
+      <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f 1<!>
     }): Int
 }
 

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnExplicitLabelNoParens.kt

@@ -1,5 +1,5 @@
 fun test2() {
-    (run @f{return@f 1}): Int
+    (run @f{<!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f 1<!>}): Int
 }
 
 fun run<T>(f: () -> T): T { return f() }

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnExplicitLabelParens.kt

@@ -1,10 +1,10 @@
 fun test() {
-    run(@f{return@f 1}): Int
+    run(@f{<!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f 1<!>}): Int
 }
 
 
 fun test1() {
-    run(@{return@ 1}): Int
+    run(@{<!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@ 1<!>}): Int
 }
 
 fun run<T>(f: () -> T): T { return f() }

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnInNestedFunction.kt

@@ -4,7 +4,7 @@ fun test() {
         if (a > 0) return "2"
         return@local "3"
       }
-      return@f 1
+      <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f 1<!>
     }): Int
 }
 

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnInNestedLambda.kt

@@ -1,9 +1,9 @@
 fun test() {
     (run @f{
       run @ff {
-        return@ff "2"
+        <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@ff "2"<!>
       }
-      return@f 1
+      <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f 1<!>
     }): Int
 }
 

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnNoCoercionToUnit.kt

@@ -1,7 +1,7 @@
 fun test(a: Int) {
     run @f{
-      if (a > 0) return@f
-      else return@f 1
+      if (a > 0) <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f<!>
+      else <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f 1<!>
     }
 }
 

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnit.kt

@@ -1,7 +1,7 @@
 fun test(a: Int) {
     (run @f{
-      if (a > 0) return@f
-      else return@f Unit.VALUE
+      if (a > 0) <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f<!>
+      else <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f Unit.VALUE<!>
     }): Unit
 }
 

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnsWithExplicitReturnType.kt

@@ -0,0 +1,11 @@
+fun test(a: Int) {
+    run @f{ (): Int ->
+      if (a > 0) return@f <!TYPE_MISMATCH!>""<!>
+      return@f 1
+    }
+
+    run { (): Int -> <!TYPE_MISMATCH!>""<!> }
+    run { (): Int -> 1 }
+}
+
+fun run<T>(f: () -> T): T { return f() }

compiler/testData/diagnostics/tests/functionLiterals/return/MixedReturnsFromLambda.kt

@@ -5,7 +5,7 @@ trait C: A
 
 fun test(a: C, b: B) {
     (run @f{
-      if (a != b) return@f a
+      if (a != b) <!RETURN_NOT_ALLOWED_EXPLICIT_RETURN_TYPE_REQUIRED!>return@f a<!>
       b
     }): A
 }