From df186337c1fd915d5ab4d5124290073307972c5b Mon Sep 17 00:00:00 2001
From: Tagir Valeev <tagir.valeev@jetbrains.com>
Date: Wed, 14 Sep 2022 13:32:10 +0200
Subject: [PATCH] [java-dfa] Do not assume that unknown terminal operation in
 stream does not escape arguments

Fixes IDEA-301057 IDEA reports 'Collection C is always empty' when pass C to custom function `SmartStream.toSet(set)`, but it may not.

GitOrigin-RevId: a649ba5bc00de249e7819e4780304ae66517ea55
---
 .../java/inliner/StreamChainInliner.java      |   5 +-
 .../fixture/CustomStreamImplementation.java   | 237 ++++++++++++++++++
 .../DataFlowInspection8Test.java              |   1 +
 3 files changed, 242 insertions(+), 1 deletion(-)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/CustomStreamImplementation.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/java/inliner/StreamChainInliner.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/java/inliner/StreamChainInliner.java
index 258ce2203cc1..24e8efa71795 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/java/inliner/StreamChainInliner.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/java/inliner/StreamChainInliner.java
@@ -71,6 +71,7 @@ public class StreamChainInliner implements CallInliner {
   private static final CallMatcher COLLECT_TERMINAL =
     instanceCall(JAVA_UTIL_STREAM_STREAM, "collect").parameterTypes("java.util.stream.Collector");
   private static final CallMatcher TO_LIST_TERMINAL = instanceCall(JAVA_UTIL_STREAM_STREAM, "toList")
+    .parameterCount(0)
     .withLanguageLevelAtLeast(LanguageLevel.JDK_16);
   private static final CallMatcher COLLECT3_TERMINAL =
     instanceCall(JAVA_UTIL_STREAM_STREAM, "collect").parameterTypes("java.util.function.Supplier",
@@ -217,9 +218,11 @@ public class StreamChainInliner implements CallInliner {
 
     @Override
     void before(CFGBuilder builder) {
+      builder.pushUnknown(); // qualifier
       for (PsiExpression arg : myCall.getArgumentList().getExpressions()) {
-        builder.pushExpression(arg).pop();
+        builder.pushExpression(arg);
       }
+      builder.call(myCall).pop();
       super.before(builder);
     }
 
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/CustomStreamImplementation.java b/java/java-tests/testData/inspection/dataFlow/fixture/CustomStreamImplementation.java
new file mode 100644
index 000000000000..2aee3629b3f0
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/CustomStreamImplementation.java
@@ -0,0 +1,237 @@
+import java.util.*;
+import java.util.function.*;
+import java.util.stream.*;
+
+class Demo {
+  void test() {
+    List<Integer> list = Arrays.asList(1, 2, 3);
+    List<Integer> target = new ArrayList<>();
+    from(list).toList(target);
+    System.out.println(target.isEmpty());
+  }
+
+  static <T> SmartStream<T> from(Collection<T> collection) {
+    return asSmart(collection.stream());
+  }
+
+  static <T> SmartStream<T> asSmart(Stream<T> stream) {
+    if (stream instanceof SmartStream<?>) {
+      return ((SmartStream<T>) stream);
+    } else {
+      return new SmartStream<>(stream);
+    }
+  }
+
+  static class SmartStream<T> implements Stream<T> {
+    private final Stream<T> stream;
+
+    protected SmartStream(Stream<T> stream) {
+      this.stream = stream;
+    }
+
+    public <C extends List<T>> C toList(C destination) {
+      return stream.collect(Collectors.toCollection(() -> destination));
+    }
+
+    @Override
+    public SmartStream<T> filter(Predicate<? super T> predicate) {
+      return asSmart(stream.filter(predicate));
+    }
+
+    @Override
+    public <R> SmartStream<R> map(Function<? super T, ? extends R> mapper) {
+      return asSmart(stream.map(mapper));
+    }
+
+    @Override
+    public IntStream mapToInt(ToIntFunction<? super T> mapper) {
+      return stream.mapToInt(mapper);
+    }
+
+    @Override
+    public LongStream mapToLong(ToLongFunction<? super T> mapper) {
+      return stream.mapToLong(mapper);
+    }
+
+    @Override
+    public DoubleStream mapToDouble(ToDoubleFunction<? super T> mapper) {
+      return stream.mapToDouble(mapper);
+    }
+
+    @Override
+    public <R> SmartStream<R> flatMap(Function<? super T, ? extends Stream<? extends R>> mapper) {
+      return asSmart(stream.flatMap(mapper));
+    }
+
+    @Override
+    public IntStream flatMapToInt(Function<? super T, ? extends IntStream> mapper) {
+      return stream.flatMapToInt(mapper);
+    }
+
+    @Override
+    public LongStream flatMapToLong(Function<? super T, ? extends LongStream> mapper) {
+      return stream.flatMapToLong(mapper);
+    }
+
+    @Override
+    public DoubleStream flatMapToDouble(Function<? super T, ? extends DoubleStream> mapper) {
+      return stream.flatMapToDouble(mapper);
+    }
+
+    @Override
+    public SmartStream<T> distinct() {
+      return asSmart(stream.distinct());
+    }
+
+    @Override
+    public SmartStream<T> sorted() {
+      return asSmart(stream.sorted());
+    }
+
+    @Override
+    public SmartStream<T> sorted(Comparator<? super T> comparator) {
+      return asSmart(stream.sorted(comparator));
+    }
+
+    @Override
+    public SmartStream<T> peek(Consumer<? super T> action) {
+      return asSmart(stream.peek(action));
+    }
+
+    @Override
+    public SmartStream<T> limit(long maxSize) {
+      return asSmart(stream.limit(maxSize));
+    }
+
+    @Override
+    public SmartStream<T> skip(long n) {
+      return asSmart(stream.skip(n));
+    }
+
+    @Override
+    public void forEach(Consumer<? super T> action) {
+      stream.forEach(action);
+    }
+
+    @Override
+    public void forEachOrdered(Consumer<? super T> action) {
+      stream.forEachOrdered(action);
+    }
+
+    @Override
+    public Object[] toArray() {
+      return stream.toArray();
+    }
+
+    @SuppressWarnings("SuspiciousToArrayCall")
+    @Override
+    public <A> A[] toArray(IntFunction<A[]> generator) {
+      return stream.toArray(generator);
+    }
+
+    @Override
+    public T reduce(T identity, BinaryOperator<T> accumulator) {
+      return stream.reduce(identity, accumulator);
+    }
+
+    @Override
+    public Optional<T> reduce(BinaryOperator<T> accumulator) {
+      return stream.reduce(accumulator);
+    }
+
+    @Override
+    public <U> U reduce(U identity, BiFunction<U, ? super T, U> accumulator, BinaryOperator<U> combiner) {
+      return stream.reduce(identity, accumulator, combiner);
+    }
+
+    @Override
+    public <R> R collect(Supplier<R> supplier, BiConsumer<R, ? super T> accumulator, BiConsumer<R, R> combiner) {
+      return stream.collect(supplier, accumulator, combiner);
+    }
+
+    @Override
+    public <R, A> R collect(Collector<? super T, A, R> collector) {
+      return stream.collect(collector);
+    }
+
+    @Override
+    public Optional<T> min(Comparator<? super T> comparator) {
+      return stream.min(comparator);
+    }
+
+    @Override
+    public Optional<T> max(Comparator<? super T> comparator) {
+      return stream.max(comparator);
+    }
+
+    @Override
+    public long count() {
+      return stream.count();
+    }
+
+    @Override
+    public boolean anyMatch(Predicate<? super T> predicate) {
+      return stream.anyMatch(predicate);
+    }
+
+    @Override
+    public boolean allMatch(Predicate<? super T> predicate) {
+      return stream.allMatch(predicate);
+    }
+
+    @Override
+    public boolean noneMatch(Predicate<? super T> predicate) {
+      return stream.noneMatch(predicate);
+    }
+
+    @Override
+    public Optional<T> findFirst() {
+      return stream.findFirst();
+    }
+
+    @Override
+    public Optional<T> findAny() {
+      return stream.findAny();
+    }
+
+    @Override
+    public Iterator<T> iterator() {
+      return stream.iterator();
+    }
+
+    @Override
+    public Spliterator<T> spliterator() {
+      return stream.spliterator();
+    }
+
+    @Override
+    public boolean isParallel() {
+      return stream.isParallel();
+    }
+
+    @Override
+    public SmartStream<T> sequential() {
+      return asSmart(stream.sequential());
+    }
+
+    @Override
+    public SmartStream<T> parallel() {
+      return asSmart(stream.parallel());
+    }
+
+    @Override
+    public SmartStream<T> unordered() {
+      return asSmart(stream.unordered());
+    }
+
+    @Override
+    public SmartStream<T> onClose(Runnable closeHandler) {
+      return asSmart(stream.onClose(closeHandler));
+    }
+
+    @Override
+    public void close() {
+      stream.close();
+    }
+  }
+}
\ No newline at end of file
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java
index cd161f05de2f..04b724f130be 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java
@@ -375,4 +375,5 @@ public class DataFlowInspection8Test extends DataFlowInspectionTestCase {
     doTest();
   }
   public void testConstructorMethodReferenceNullability() { doTest(); }
+  public void testCustomStreamImplementation() { doTest(); }
 }
\ No newline at end of file