support raise ... from in Python 3

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

@@ -303,6 +303,10 @@ public class StatementParsing extends Parsing implements ITokenTypeRemapper {
           getExpressionParser().parseSingleExpression(false);
         }
       }
+      else if (myBuilder.getTokenType() == PyTokenTypes.FROM_KEYWORD) {
+        myBuilder.advanceLexer();
+        getExpressionParser().parseSingleExpression(false);
+      }
     }
     checkEndOfStatement(inSuite);
     raiseStatement.done(PyElementTypes.RAISE_STATEMENT);

python/testData/psi/RaiseFrom.py

@@ -0,0 +1 @@
+raise SyntaxError from exc

python/testData/psi/RaiseFrom.txt

@@ -0,0 +1,11 @@
+PyFile:RaiseFrom.py
+  PyRaiseStatement
+    PsiElement(Py:RAISE_KEYWORD)('raise')
+    PsiWhiteSpace(' ')
+    PyReferenceExpression: SyntaxError
+      PsiElement(Py:IDENTIFIER)('SyntaxError')
+    PsiWhiteSpace(' ')
+    PsiElement(Py:FROM_KEYWORD)('from')
+    PsiWhiteSpace(' ')
+    PyReferenceExpression: exc
+      PsiElement(Py:IDENTIFIER)('exc')

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

@@ -154,6 +154,10 @@ public class PythonParsingTest extends ParsingTestCase {
     doTest(LanguageLevel.PYTHON30);
   }
 
+  public void testRaiseFrom() throws Exception {
+    doTest(LanguageLevel.PYTHON30);
+  }
+
   public void doTest() throws Exception {
     doTest(LanguageLevel.PYTHON25);
   }