Suggestions

error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ClassCastLambdaUsage.java

@@ -54,9 +54,9 @@ public Description matchLambdaExpression(LambdaExpressionTree tree, VisitorState
         || type.isPrimitive()
         || type.getKind() == TypeKind.TYPEVAR) {
       /*
-       * The method reference syntax does not support casting to parameterized types. Additionally,
-       * `Class#cast` does not support the same range of type conversions between (boxed) primitive
-       * types as the cast operator.
+       * The method reference syntax does not support casting to parameterized types, and type
+       * variables aren't supported either. Additionally, `Class#cast` does not support the same
+       * range of type conversions between (boxed) primitive types as the cast operator.
        */
       // XXX: Depending on the declared type of the value being cast, in some cases we _can_ rewrite
       // primitive casts. Add support for this.

error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ClassCastLambdaUsageTest.java

@@ -16,7 +16,7 @@ void identification() {
             "import java.util.stream.Stream;",
             "",
             "class A {",
-            "  void m() {",
+            "  <T> void m() {",
             "    Number localVariable = 0;",
             "",
             "    Stream.of(0).map(i -> i);",
@@ -36,13 +36,10 @@ void identification() {
             "    Stream.of(ImmutableSet.of(7)).map(s -> (ImmutableSet<?>) s);",
             "    Stream.of(8).reduce((a, b) -> (Integer) a);",
             "    IntStream.of(9).mapToObj(i -> (char) i);",
+            "    Stream.of(10).map(i -> (T) i);",
             "",
             "    // BUG: Diagnostic contains:",
-            "    Stream.of(10).map(i -> (Integer) i);",
-            "  }",
-            "",
-            "  private <T> void m2() {",
-            "    Stream.of(11).map(i -> (T) i);",
+            "    Stream.of(11).map(i -> (Integer) i);",
             "  }",
             "}")
         .doTest();