PY-19989 Don't store results of implicit relative import in PythonPathCache

python/psi-api/src/com/jetbrains/python/psi/impl/PyPsiUtils.java

@@ -19,7 +19,6 @@ import com.google.common.base.Preconditions;
 import com.intellij.lang.ASTNode;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.module.Module;
-import com.intellij.openapi.util.Condition;
 import com.intellij.openapi.util.Couple;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.*;
@@ -604,6 +603,14 @@ public class PyPsiUtils {
     Preconditions.checkArgument(!module.isDisposed(), String.format("Module %s is disposed", module));
   }
 
+  @NotNull
+  public static PsiFileSystemItem getFileSystemItem(@NotNull PsiElement element) {
+    if (element instanceof PsiFileSystemItem) {
+      return (PsiFileSystemItem)element;
+    }
+    return element.getContainingFile();
+  }
+
   private static abstract class TopLevelVisitor extends PyRecursiveElementVisitor {
     public void visitPyElement(final PyElement node) {
       super.visitPyElement(node);

python/src/com/jetbrains/python/psi/resolve/QualifiedNameResolverImpl.java

@@ -28,15 +28,13 @@ import com.intellij.openapi.project.Project;
 import com.intellij.openapi.projectRoots.Sdk;
 import com.intellij.openapi.roots.FileIndexFacade;
 import com.intellij.openapi.vfs.VirtualFile;
-import com.intellij.psi.PsiDirectory;
-import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiFile;
-import com.intellij.psi.PsiNamedElement;
+import com.intellij.psi.*;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.QualifiedName;
 import com.jetbrains.python.codeInsight.userSkeletons.PyUserSkeletonsUtil;
 import com.jetbrains.python.console.PydevConsoleRunner;
 import com.jetbrains.python.facet.PythonPathContributingFacet;
+import com.jetbrains.python.psi.LanguageLevel;
 import com.jetbrains.python.psi.PyFile;
 import com.jetbrains.python.psi.PyUtil;
 import com.jetbrains.python.psi.impl.PyBuiltinCache;
@@ -44,6 +42,7 @@ import com.jetbrains.python.psi.impl.PyImportResolver;
 import com.jetbrains.python.psi.impl.PyPsiUtils;
 import com.jetbrains.python.sdk.PySdkUtil;
 import com.jetbrains.python.sdk.PythonSdkType;
+import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -52,6 +51,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 
+import static com.jetbrains.python.psi.PyUtil.as;
+
 /**
  * Resolves the specified qualified name in the specified context (module, all modules or a file) to a file or directory.
  *
@@ -235,6 +236,7 @@ public class QualifiedNameResolverImpl implements RootVisitor, QualifiedNameReso
 
     final PsiFile footholdFile = myContext.getFootholdFile();
     checkValidForTests(footholdFile);
+    boolean foundRelativeImport = false;
     if (myRelativeLevel >= 0 && footholdFile != null && !PyUserSkeletonsUtil.isUnderUserSkeletonsDirectory(footholdFile)) {
       PsiDirectory dir = footholdFile.getContainingDirectory();
       checkValidForTests(dir);
@@ -246,12 +248,13 @@ public class QualifiedNameResolverImpl implements RootVisitor, QualifiedNameReso
       PsiElement module = resolveModuleAt(dir);
       checkValidForTests(module);
       if (module != null) {
+        foundRelativeImport = isRelativeImportResult(dir, module);
         addRoot(module, true);
       }
     }
 
     final PythonPathCache cache = findMyCache();
-    final boolean mayCache = cache != null && !myWithoutRoots && !myWithoutForeign;
+    final boolean mayCache = cache != null && !myWithoutRoots && !myWithoutForeign && !foundRelativeImport;
     if (mayCache) {
       final List<PsiElement> cachedResults = cache.get(myQualifiedName);
       if (cachedResults != null) {
@@ -293,6 +296,22 @@ public class QualifiedNameResolverImpl implements RootVisitor, QualifiedNameReso
     return results;
   }
 
+  
+  private boolean isRelativeImportResult(@NotNull PsiDirectory rootDirectory, @NotNull PsiElement result) {
+    if (myRelativeLevel > 0) {
+      return true;
+    }
+    final boolean isPython2 = LanguageLevel.forElement(rootDirectory).isOlderThan(LanguageLevel.PYTHON30);
+    if (myRelativeLevel == 0 && isPython2 && PyUtil.isPackage(rootDirectory, false, null)) {
+      // Candidate for implicit relative import doesn't necessarily means that the same module cannot be imported absolutely 
+      final PsiFileSystemItem moduleOrPackage = as(result, PsiFileSystemItem.class);
+      if (moduleOrPackage != null && !myQualifiedName.equals(QualifiedNameFinder.findShortestImportableQName(moduleOrPackage))) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   /**
    * Resolve relative imports from sdk root to the skeleton dir
    */
@@ -421,6 +440,7 @@ public class QualifiedNameResolverImpl implements RootVisitor, QualifiedNameReso
    *
    * @param directory where to start from; top qualifier will be searched for here.
    */
+  @Contract("null -> null")
   @Nullable
   public PsiElement resolveModuleAt(@Nullable PsiDirectory directory) {
     // prerequisites

python/testData/resolve/multiFile/ambiguousImplicitRelativeImport/pkg/__init__.py

@@ -0,0 +1,2 @@
+import mod
+        <ref>

python/testData/resolve/multiFile/ambiguousImplicitRelativeImport/pkg2/__init__.py

@@ -0,0 +1,2 @@
+import mod
+        <ref>

python/testSrc/com/jetbrains/python/PyMultiFileResolveTest.java

@@ -18,6 +18,8 @@ package com.jetbrains.python;
 import com.google.common.collect.Lists;
 import com.intellij.openapi.module.Module;
 import com.intellij.openapi.projectRoots.Sdk;
+import com.intellij.openapi.roots.ModuleRootManager;
+import com.intellij.openapi.vfs.VfsUtilCore;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.psi.*;
 import com.intellij.psi.impl.source.PsiFileImpl;
@@ -26,10 +28,14 @@ import com.jetbrains.python.fixtures.PyMultiFileResolveTestCase;
 import com.jetbrains.python.fixtures.PyResolveTestCase;
 import com.jetbrains.python.fixtures.PyTestCase;
 import com.jetbrains.python.psi.*;
+import com.jetbrains.python.psi.impl.PyPsiUtils;
 import com.jetbrains.python.sdk.PythonSdkType;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.Arrays;
 import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 /**
  * @author yole
@@ -459,4 +465,29 @@ public class PyMultiFileResolveTest extends PyMultiFileResolveTestCase {
       }
     }
   }
+
+  // PY-19989
+  public void testAmbiguousImplicitRelativeImport() {
+    prepareTestDirectory();
+    assertSameElements(doMultiResolveAndGetFileUrls("pkg2/__init__.py"), "pkg2/mod.py");
+    assertSameElements(doMultiResolveAndGetFileUrls("pkg/__init__.py"), "pkg/mod.py");
+  }
+
+  @NotNull
+  private List<String> doMultiResolveAndGetFileUrls(@NotNull String currentFilePath) {
+    myFixture.configureByFile(currentFilePath);
+    final PsiReference reference = PyResolveTestCase.findReferenceByMarker(myFixture.getFile());
+    final VirtualFile root = ModuleRootManager.getInstance(myFixture.getModule()).getSourceRoots()[0];
+
+    final Stream<PsiFileSystemItem> fileSystemItems;
+    if (reference instanceof PsiPolyVariantReference) {
+      final ResolveResult[] results = ((PsiPolyVariantReference)reference).multiResolve(false);
+      fileSystemItems = Arrays.stream(results).map(r -> PyPsiUtils.getFileSystemItem(r.getElement()));
+    }
+    else {
+      fileSystemItems = Stream.of(PyPsiUtils.getFileSystemItem(reference.resolve()));
+    }
+    return fileSystemItems.map(f -> VfsUtilCore.getRelativeLocation(f.getVirtualFile(), root)).collect(Collectors.toList());
+    
+  }
 }