tweak decorator parsing so that following line comment is outside the text range of PyDecorator (PY-5912)

python/src/com/jetbrains/python/parsing/FunctionParsing.java

@@ -85,10 +85,18 @@ public class FunctionParsing extends Parsing {
         getExpressionParser().parseArgumentList();
       }
       else { // empty arglist node, so we always have it
-        myBuilder.mark().done(PyElementTypes.ARGUMENT_LIST);
+        PsiBuilder.Marker argListMarker = myBuilder.mark();
+        argListMarker.setCustomEdgeTokenBinders(LeftBiasedWhitespaceBinder.INSTANCE, null);
+        argListMarker.done(PyElementTypes.ARGUMENT_LIST);
+      }
+      if (atToken(PyTokenTypes.STATEMENT_BREAK)) {
+        decoratorMarker.done(PyElementTypes.DECORATOR_CALL);
+        nextToken();
+      }
+      else {
+        myBuilder.error(message("PARSE.expected.statement.break"));
+        decoratorMarker.done(PyElementTypes.DECORATOR_CALL);
       }
-      checkMatches(PyTokenTypes.STATEMENT_BREAK, message("PARSE.expected.statement.break"));
-      decoratorMarker.done(PyElementTypes.DECORATOR_CALL);
       decorated = true;
     }
     if (decorated) decoListMarker.done(PyElementTypes.DECORATOR_LIST);

python/src/com/jetbrains/python/parsing/LeftBiasedWhitespaceBinder.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2000-2013 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.jetbrains.python.parsing;
+
+import com.intellij.lang.WhitespacesAndCommentsBinder;
+import com.intellij.psi.tree.IElementType;
+
+import java.util.List;
+
+/**
+ * @author yole
+ */
+public class LeftBiasedWhitespaceBinder implements WhitespacesAndCommentsBinder {
+  public static LeftBiasedWhitespaceBinder INSTANCE = new LeftBiasedWhitespaceBinder();
+
+  @Override
+  public int getEdgePosition(List<IElementType> tokens, boolean atStreamEdge, TokenTextGetter getter) {
+    return 0;
+  }
+}

python/testData/inspections/PyArgumentListInspection/decorators.py

@@ -19,7 +19,7 @@ def f9():
 
 def deco2(p1, p2): pass
 
-<warning descr="Parameter 'p2' unfilled">@deco2 # fail: missing p2</warning>
+<warning descr="Parameter 'p2' unfilled">@deco2</warning> # fail: missing p2
 def f10():
   pass
 
@@ -61,7 +61,7 @@ class Dec2:
 def f17():
   pass
 
-<warning descr="Parameter 'p2' unfilled">@Dec2 # fail: no p2</warning>
+<warning descr="Parameter 'p2' unfilled">@Dec2</warning> # fail: no p2
 def f18():
   pass
 

python/testData/psi/CommentAfterDecorator.py

@@ -0,0 +1,3 @@
+@uncallable_deco        #  some comment
+def f():
+    pass

python/testData/psi/CommentAfterDecorator.txt

@@ -0,0 +1,23 @@
+PyFile:CommentAfterDecorator.py
+  PyFunction('f')
+    PyDecoratorList
+      PyDecorator: @uncallable_deco
+        PsiElement(Py:AT)('@')
+        PyReferenceExpression: uncallable_deco
+          PsiElement(Py:IDENTIFIER)('uncallable_deco')
+        PyArgumentList
+          <empty list>
+      PsiWhiteSpace('        ')
+      PsiComment(Py:END_OF_LINE_COMMENT)('#  some comment')
+    PsiWhiteSpace('\n')
+    PsiElement(Py:DEF_KEYWORD)('def')
+    PsiWhiteSpace(' ')
+    PsiElement(Py:IDENTIFIER)('f')
+    PyParameterList
+      PsiElement(Py:LPAR)('(')
+      PsiElement(Py:RPAR)(')')
+    PsiElement(Py:COLON)(':')
+    PsiWhiteSpace('\n    ')
+    PyStatementList
+      PyPassStatement
+        PsiElement(Py:PASS_KEYWORD)('pass')

python/testSrc/com/jetbrains/python/PythonParsingTest.java

@@ -402,6 +402,10 @@ public class PythonParsingTest extends ParsingTestCase {
     doTest();
   }
 
+  public void testCommentAfterDecorator() {  // PY-5912
+    doTest();
+  }
+
   public void doTest(LanguageLevel languageLevel) {
     LanguageLevel prev = myLanguageLevel;
     myLanguageLevel = languageLevel;