escaping # in verbose regexps is not redundant (PY-6545)

python/src/com/jetbrains/python/psi/impl/PyStringLiteralExpressionImpl.java

@@ -1,17 +1,18 @@
 package com.jetbrains.python.psi.impl;
 
 import com.intellij.lang.ASTNode;
+import com.intellij.lang.Language;
+import com.intellij.lang.injection.InjectedLanguageManager;
+import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.util.Ref;
 import com.intellij.openapi.util.TextRange;
-import com.intellij.psi.LiteralTextEscaper;
-import com.intellij.psi.PsiLanguageInjectionHost;
-import com.intellij.psi.PsiReference;
-import com.intellij.psi.PsiReferenceService;
+import com.intellij.psi.*;
 import com.intellij.psi.impl.source.resolve.reference.ReferenceProvidersRegistry;
 import com.intellij.psi.impl.source.tree.LeafElement;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.jetbrains.python.PyTokenTypes;
+import com.jetbrains.python.codeInsight.regexp.PythonVerboseRegexpLanguage;
 import com.jetbrains.python.lexer.PythonHighlightingLexer;
 import com.jetbrains.python.psi.*;
 import com.jetbrains.python.psi.types.PyType;
@@ -396,9 +397,25 @@ public class PyStringLiteralExpressionImpl extends PyElementImpl implements PySt
   }
 
   public boolean characterNeedsEscaping(char c) {
+    if (c == '#') {
+      return isVerboseInjection();
+    }
     return c == ']' || c == '}' || c == '\"' || c == '\'';
   }
 
+  private boolean isVerboseInjection() {
+    List<Pair<PsiElement,TextRange>> files = InjectedLanguageManager.getInstance(getProject()).getInjectedPsiFiles(this);
+    if (files != null) {
+      for (Pair<PsiElement, TextRange> file : files) {
+        Language language = file.getFirst().getLanguage();
+        if (language == PythonVerboseRegexpLanguage.INSTANCE) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
   public boolean supportsPerl5EmbeddedComments() {
     return true;
   }

python/testData/regexp/verboseEscapedHash.py

@@ -0,0 +1,15 @@
+import re
+
+urlparts = re.compile(
+    r"""
+        (?P<scheme>http|https)
+        ://
+        (?P<netloc>(?:(?!/|\?|\#)\S)*)
+        /?
+        (?P<path>(?:(?!\?|\#)\S)*)
+        \??
+        (?P<query>(?:(?!\#)\S)*)
+        \#?
+        (?P<fragment>[\S]*)
+    """, re.VERBOSE
+)

python/testSrc/com/jetbrains/python/PyRegexpTest.java

@@ -55,6 +55,10 @@ public class PyRegexpTest extends PyTestCase {
     doTestHighlighting();
   }
 
+  public void testVerboseEscapedHash() {  // PY-6545
+    doTestHighlighting();
+  }
+
   private void doTestHighlighting() {
     myFixture.testHighlighting(true, false, true, "regexp/" + getTestName(true) + ".py");
   }

python/testSrc/com/jetbrains/python/PythonAllTestsSuite.java

@@ -105,7 +105,8 @@ public class PythonAllTestsSuite {
     PyJoinLinesTest.class,
     PyStatementListTest.class,
     PyChangeSignatureTest.class,
-    PyCommenterTest.class
+    PyCommenterTest.class,
+    PyRegexpTest.class
   };
 
   public static TestSuite suite() {