IDEA-204310: Decompiler adds redundant imports for lambdas

src/org/jetbrains/java/decompiler/modules/decompiler/exps/NewExprent.java

@@ -143,7 +143,8 @@ public class NewExprent extends Exprent {
     if (anonymous) {
       ClassNode child = DecompilerContext.getClassProcessor().getMapRootClasses().get(newType.value);
 
-      if (!enumConst) {
+      // IDEA-204310 - avoid backtracking later on for lambdas (causes spurious imports)
+      if (!enumConst && (!lambda || DecompilerContext.getOption(IFernflowerPreferences.LAMBDA_TO_ANONYMOUS_CLASS))) {
         String enclosing = null;
 
         if (!lambda && constructor != null) {

testData/results/TestClassLambda.dec

@@ -5,10 +5,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.OptionalInt;
-import java.util.function.Consumer;
-import java.util.function.Function;
 import java.util.function.IntBinaryOperator;
-import java.util.function.Predicate;
 import java.util.function.Supplier;
 
 public class TestClassLambda {
@@ -90,43 +87,51 @@ public class TestClassLambda {
 
 class 'pkg/TestClassLambda' {
    method 'lambda$testLambda$0 (ILjava/lang/Integer;)V' {
-      0      20
-      2      20
-      5      20
-      6      20
-      7      21
-      c      21
-      e      21
-      11      21
-      12      21
-      15      22
+      0      17
+      2      17
+      5      17
+      6      17
+      7      18
+      c      18
+      e      18
+      11      18
+      12      18
+      15      19
    }
 
    method 'testLambda ()V' {
-      7      17
-      8      17
-      e      17
-      f      17
-      15      17
-      16      17
-      1c      17
-      1d      17
-      23      17
-      24      17
-      2a      17
-      2c      17
-      33      17
-      35      17
-      39      17
-      3c      17
-      3d      18
-      40      18
-      41      18
-      4a      19
-      4f      23
+      7      14
+      8      14
+      e      14
+      f      14
+      15      14
+      16      14
+      1c      14
+      1d      14
+      23      14
+      24      14
+      2a      14
+      2c      14
+      33      14
+      35      14
+      39      14
+      3c      14
+      3d      15
+      40      15
+      41      15
+      4a      16
+      4f      20
    }
 
    method 'lambda$testLambda1$1 (I)V' {
+      0      25
+      a      25
+      13      25
+      16      25
+      19      26
+   }
+
+   method 'lambda$testLambda1$2 (I)V' {
       0      28
       a      28
       13      28
@@ -134,153 +139,145 @@ class 'pkg/TestClassLambda' {
       19      29
    }
 
-   method 'lambda$testLambda1$2 (I)V' {
-      0      31
-      a      31
-      13      31
-      16      31
-      19      32
-   }
-
    method 'testLambda1 ()V' {
-      0      26
-      3      26
-      4      26
-      b      29
-      12      32
-      13      33
+      0      23
+      3      23
+      4      23
+      b      26
+      12      29
+      13      30
    }
 
    method 'lambda$testLambda2$3 (II)I' {
-      2      37
-      5      37
+      2      34
+      5      34
    }
 
    method 'testLambda2 ()V' {
-      5      36
-      9      39
+      5      33
+      9      36
    }
 
    method 'testLambda3 ()V' {
-      5      42
-      9      43
+      5      39
+      9      40
    }
 
    method 'testLambda4 ()V' {
-      5      46
-      9      47
+      5      43
+      9      44
    }
 
    method 'testLambda5 ()V' {
-      0      50
-      2      50
-      e      51
-      12      52
+      0      47
+      2      47
+      e      48
+      12      49
    }
 
    method 'lambda$testLambda6$4 (IILjava/lang/String;)Z' {
-      2      59
-      5      59
-      9      59
-      d      59
-      15      59
+      2      56
+      5      56
+      9      56
+      d      56
+      15      56
    }
 
    method 'testLambda6 ()V' {
-      7      55
-      9      56
-      e      56
-      f      56
-      10      56
-      12      57
-      17      57
-      18      57
-      19      57
-      22      58
-      28      61
+      7      52
+      9      53
+      e      53
+      f      53
+      10      53
+      12      54
+      17      54
+      18      54
+      19      54
+      22      55
+      28      58
    }
 
    method 'testLambda7 ([Ljava/lang/annotation/Annotation;)V' {
-      1      64
-      9      64
-      f      65
+      1      61
+      9      61
+      f      62
    }
 
    method 'reduce (Ljava/util/function/IntBinaryOperator;)Ljava/util/OptionalInt;' {
-      0      68
-      1      68
+      0      65
+      1      65
    }
 
    method 'function (Ljava/util/function/Supplier;)Ljava/lang/String;' {
-      1      72
-      6      72
-      9      72
+      1      69
+      6      69
+      9      69
    }
 
    method 'localMax (II)I' {
-      0      76
-      1      76
+      0      73
+      1      73
    }
 
    method 'lambda$null$5 (I)V' {
-      0      83
-      a      83
-      13      83
-      16      83
-      19      84
+      0      80
+      a      80
+      13      80
+      16      80
+      19      81
    }
 
    method 'lambda$nestedLambdas$6 (I)V' {
-      6      84
-      7      85
-      11      85
-      1a      85
-      1d      85
-      20      86
+      6      81
+      7      82
+      11      82
+      1a      82
+      1d      82
+      20      83
    }
 
    method 'nestedLambdas ()V' {
-      0      80
-      1      80
-      8      86
-      9      87
+      0      77
+      1      77
+      8      83
+      9      84
    }
 }
 
 Lines mapping:
-29 <-> 18
-30 <-> 19
-32 <-> 20
-33 <-> 21
-34 <-> 22
-35 <-> 23
-36 <-> 24
-39 <-> 27
-40 <-> 30
-41 <-> 33
-42 <-> 34
-45 <-> 37
-46 <-> 40
-49 <-> 43
-50 <-> 44
-53 <-> 47
-54 <-> 48
-57 <-> 51
-58 <-> 52
-59 <-> 53
-62 <-> 56
-63 <-> 57
-64 <-> 58
-65 <-> 59
-66 <-> 62
-69 <-> 65
-70 <-> 66
-73 <-> 69
-77 <-> 73
-81 <-> 77
-85 <-> 81
-86 <-> 87
-87 <-> 85
-88 <-> 86
-89 <-> 87
-90 <-> 88
+29 <-> 15
+30 <-> 16
+32 <-> 17
+33 <-> 18
+34 <-> 19
+35 <-> 20
+36 <-> 21
+39 <-> 24
+40 <-> 27
+41 <-> 30
+42 <-> 31
+45 <-> 34
+46 <-> 37
+49 <-> 40
+50 <-> 41
+53 <-> 44
+54 <-> 45
+57 <-> 48
+58 <-> 49
+59 <-> 50
+62 <-> 53
+63 <-> 54
+64 <-> 55
+65 <-> 56
+66 <-> 59
+69 <-> 62
+70 <-> 63
+73 <-> 66
+77 <-> 70
+81 <-> 74
+85 <-> 78
+86 <-> 84
+87 <-> 82
+88 <-> 83
+89 <-> 84
+90 <-> 85