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