From f73ae3f9bf784d6470249adaf57b04cf624438df Mon Sep 17 00:00:00 2001
From: Andrey Vlasovskikh <andrey.vlasovskikh@gmail.com>
Date: Fri, 22 May 2015 13:07:48 +0200
Subject: [PATCH] Fixed unresolved reference for parameters which methods are
 invoked inside the function body (PY-11541)

We may get stuck in a recursive resolve loop (that results in unresolved
references) if we match arguments to parameters for a call where the
callee is a reference to the named parameter itself.

The loop used to go like this:

1. Get the type of 'foo.bar' in 'foo.bar(foo)'
2. Get the type of 'foo' in 'def f(foo)'
3. Find the structural type for 'foo'
4. Ask nested calls where 'foo' is a parameter
5. Try to match args to params in 'foo.bar(foo)'
6. Resolve 'foo.bar'
7. Get the type of 'foo.bar' in 'foo.bar(foo')
8. Since the 'foo.bar' is evaluating, it's 'null' for preventing
   recursion
9. So 'foo.bar' resolves to 'null' which is false
---
 .../python/psi/impl/PyNamedParameterImpl.java | 28 +++++++++++++++----
 .../baseStringCheck.py                        |  4 +++
 .../PyUnresolvedReferencesInspectionTest.java |  5 ++++
 3 files changed, 32 insertions(+), 5 deletions(-)
 create mode 100644 python/testData/inspections/PyUnresolvedReferencesInspection/baseStringCheck.py

diff --git a/python/src/com/jetbrains/python/psi/impl/PyNamedParameterImpl.java b/python/src/com/jetbrains/python/psi/impl/PyNamedParameterImpl.java
index 7c89a1c4770c..76e96692194c 100644
--- a/python/src/com/jetbrains/python/psi/impl/PyNamedParameterImpl.java
+++ b/python/src/com/jetbrains/python/psi/impl/PyNamedParameterImpl.java
@@ -349,11 +349,29 @@ public class PyNamedParameterImpl extends PyBaseElementImpl<PyNamedParameterStub
   }
 
   @Nullable
-  private static PyNamedParameter getParameterByCallArgument(@NotNull PsiElement element, @NotNull TypeEvalContext context) {
-    final PyCallExpression call = PsiTreeUtil.getParentOfType(element, PyCallExpression.class);
-    if (call != null) {
-      final PyArgumentList argumentList = call.getArgumentList();
-      if (argumentList != null) {
+  private PyNamedParameter getParameterByCallArgument(@NotNull PsiElement element, @NotNull TypeEvalContext context) {
+    final PyArgumentList argumentList = PsiTreeUtil.getParentOfType(element, PyArgumentList.class);
+    if (argumentList != null) {
+      boolean elementIsArgument = false;
+      for (PyExpression argument : argumentList.getArgumentExpressions()) {
+        if (PyPsiUtils.flattenParens(argument) == element) {
+          elementIsArgument = true;
+          break;
+        }
+      }
+      final PyCallExpression callExpression = argumentList.getCallExpression();
+      if (elementIsArgument && callExpression != null) {
+        final PyExpression callee = callExpression.getCallee();
+        if (callee instanceof PyReferenceExpression) {
+          final PyReferenceExpression calleeReferenceExpr = (PyReferenceExpression)callee;
+          final PyExpression firstQualifier = PyPsiUtils.getFirstQualifier(calleeReferenceExpr);
+          if (firstQualifier != null) {
+            final PsiReference ref = firstQualifier.getReference();
+            if (ref != null && ref.isReferenceTo(this)) {
+              return null;
+            }
+          }
+        }
         final PyResolveContext resolveContext = PyResolveContext.noImplicits().withTypeEvalContext(context);
         final CallArgumentsMapping mapping = argumentList.analyzeCall(resolveContext);
         for (Map.Entry<PyExpression, PyNamedParameter> entry : mapping.getPlainMappedParams().entrySet()) {
diff --git a/python/testData/inspections/PyUnresolvedReferencesInspection/baseStringCheck.py b/python/testData/inspections/PyUnresolvedReferencesInspection/baseStringCheck.py
new file mode 100644
index 000000000000..a91281d759d6
--- /dev/null
+++ b/python/testData/inspections/PyUnresolvedReferencesInspection/baseStringCheck.py
@@ -0,0 +1,4 @@
+def repl(s):
+    if not isinstance(s, basestring):
+        return s
+    return s.replace(s.replace('a', 'b'), s)
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyUnresolvedReferencesInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyUnresolvedReferencesInspectionTest.java
index 5981c6b74767..1499084c4def 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyUnresolvedReferencesInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyUnresolvedReferencesInspectionTest.java
@@ -505,6 +505,11 @@ public class PyUnresolvedReferencesInspectionTest extends PyInspectionTestCase {
     doTest();
   }
 
+  // PY-11541
+  public void testBaseStringCheck() {
+    doTest();
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {